#!/usr/bin/env perl

use strict;
use warnings;

use Compress::Raw::Lzma qw (LZMA_STREAM_END LZMA_DICT_SIZE_MIN);
use File::Basename;

# author:
# philsmd
# magnum (added proper handling of BCJ et. al. and adapt to JtR use)

# version:
# 2.0

# date released:
# April 2015

# date last updated:
# April 10 2024

# dependencies:
# Compress::Raw::Lzma
# File::Basename

# supported file types:
# - is able to identify and parse .7z files
# - is able to identify and parse splitted .7z files (.7z.001, .7z.002, ...)
# - is able to identify and parse regular (non-packed) .sfx files

# install dependencies like this:
#    sudo cpan Compress::Raw::Lzma
# or sudo apt-get install libcompress-raw-lzma-perl
# or sudo perl -MCPAN -e 'install Compress::Raw::Lzma'


#
# Explanation of the "hash" format:
#

# the fields of this format are separate by the dollar ("$") sign:
# ("xyz" means that the string xyz is used literally, brackets indicate variables)
#
# "$"
# "7z"
# "$"
# [data type indicator]           # see "Explanation of the data type indicator" below
# "$"
# [cost factor]                   # means: 2 ^ [cost factor] iterations
# "$"
# [length of salt]
# "$"
# [salt]
# "$"
# [length of iv]                  # the initialization vector length
# "$"
# [iv]                            # the initialization vector itself
# "$"
# [CRC32]                         # the actual "hash"
# "$"
# [length of encrypted data]      # the encrypted data length in bytes
# "$"
# [length of decrypted data]      # the decrypted data length in bytes
# "$"
# [encrypted data]                # the encrypted (and possibly also compressed) data

# in case the data was not truncated and a decompression step is needed to verify the CRC32, these fields are appended:
# "$"
# [length of data for CRC32]      # the length of the first "file" needed to verify the CRC32 checksum
# "$"
# [coder attributes]              # most of the coders/decompressors need some attributes (e.g. encoded lc, pb, lp, dictSize values)

# in case a preprocessor is used, this field is appended:
# "$"
# [preprocessor attributes]       # the preprocessor attributes are appended after the main coder attributes

#
# Explanation of the data type indicator
#

# This field is the first field after the hash signature (i.e. after "$7z$).
# Whenever the data was longer than the value of PASSWORD_RECOVERY_TOOL_DATA_LIMIT and the data could be truncated due to the padding attack,
# the value of this field will be set to 128.
#
# If no truncation is used:
# - the value will be 0 if the data doesn't need to be decompressed to check the CRC32 checksum
# - all values different from 128, but greater than 0, indicate that the data must be decompressed as follows:
#
# LOWER NIBBLE (4 bits, type & 0xf)
#   - 1 means that the data must be decompressed using the LZMA1 decompressor
#   - 2 means that the data must be decompressed using the LZMA2 decompressor
#   - 3 means that the data must be decompressed using the PPMD decompressor
#   - 4 reserved (future use)
#   - 5 reserved (future use)
#   - 6 means that the data must be decompressed using the BZIP2 decompressor
#   - 7 means that the data must be decompressed using the DEFLATE decompressor
#   - 8 .. 15 reserved (future use)
#
# UPPER NIBBLE (4 bits, (type >> 4) & 0xf)
#   - 1 means that the data must be post-processed using BCJ (x86)
#   - 2 means that the data must be post-processed using BCJ2 (four data streams needed)
#   - 3 means that the data must be post-processed using PPC (big-endian)
#   - 4 means that the data must be post-processed using IA64
#   - 5 means that the data must be post-processed using ARM (little-endian)
#   - 6 means that the data must be post-processed using ARMT (little-endian)
#   - 7 means that the data must be post-processed using SPARC
#   - 8 unavailable since this indicates TRUNCATION (128 == 0x80 == 8 << 4)
#   - 9 means that the data must be post-processed using DELTA
#   - 10 .. 15 reserved (future use)

# Truncated data can only be verified using the padding attack and therefore combinations between truncation + a compressor are not allowed.
# Therefore, whenever the value is 128 or 0, neither coder attributes nor the length of the data for the CRC32 check is within the output.
# On the other hand, for all values above or equal 1 and smaller than 128, both coder attributes and the length for CRC32 check is in the output.

# Whenever the data needs to be either (pre)processed by multiple (2+) filters or whenever the data needs to be decompressed by multiple (2+) decompression algorithms,
# the attribute list (the fields "preprocessor attributes" and "coder attributes" accordingly) will be a comma-separated list of fields with type, order/position and attribute indicators.
#
# The rules for this Multiple Compressor(s)/Preprocessor(s) list are as follows:
#   - all (additional) methods/coders need to be specified in the output hash format (the fields "coder attributes" and "preprocessor attributes" accordingly), even if they have no attributes
#   - the format is a comma-separated list of type and order indicator (for both fields: compressor and preprocessor attributes), followed by an underscore (_), followed by the attribute itself
#   - the first attribute/item/codec for both fields (compressor and preprocessor attributes) needs no type and order indicator, only attributes
#   - the type and position/order of the first decompressor/filter are implied (it's always the first decompressor/filter and the type is in the "data type indicator" field)
#   - this also means that the field "data type indicator" (see format above) only indicates the first decompressor (if used) and (also, if used) the first preprocessing filter (this is also due to compatibility reasons with older formats)
#   - for the additional (2+) decompressors/filters, the first number after the comma is the type and order indicator, after which follows an underscore (_) and the attributes themself (could be empty/no attribute value for some codecs)
#   - special case: the "coder attributes" field could start with a comma (and has also a type and order indicator) in the unlikely case where during archive generation a filter was applied after the final compression of the data. Otherwise it's always the case that the decompressor needs to be applied first
#
# Multiple Compressor(s)/Preprocessor(s) type and order indicator (it is one combined field/number):
#   - upper nibble (4 bits, indicator >> 4) indicates the compressor/preprocessor method/type/codec (LZMA2, Delta, BCJ etc)
#   - lower nibble (4 bits, indicator & 0xf) indicates the order/position (the step at which the (de)compressor/(pre)processor needs to be applied). The values are incrementing, the counter starts with 1

#
# Constants
#

# cracker specific stuff

my $ANALYZE_ALL_STREAMS_TO_FIND_SHORTEST_DATA_BUF = 1;

my $SHOW_LIST_OF_ALL_STREAMS = 0; # $ANALYZE_ALL_STREAMS_TO_FIND_SHORTEST_DATA_BUF must be set to 1 to list/debug all streams
my $SHOW_UNSUPPORTED_CODER_WARNING = 1;

my $SHORTEN_HASH_LENGTH_TO_CRC_LENGTH = 1; # only output the bytes needed for the checksum of the first file (plus a fixed length
                                           # header at the very beginning of the stream; plus additional +5% to cover the exception
                                           # that the compressed file is slightly longer than the raw file)

my $SHORTEN_HASH_FIXED_HEADER  = 32.5;  # at the beginning of the compressed stream we have some header info
                                        # (shortened hash can't really be shorter than the metadata needed for decompression)
                                        # the extra +0.5 is used to round up (we use integer numbers)
my $SHORTEN_HASH_EXTRA_PERCENT = 5;     # the compressed stream could be slightly longer than the underlying data (special cases)
                                        # in percent: i.e. x % == (x / 100)

my $DISPLAY_SENSITIVE_DATA_WARNING = 1; # 0 means skip or use --skip-sensitive-data-warning

my $PASSWORD_RECOVERY_TOOL_NAME = "hashcat";
my $PASSWORD_RECOVERY_TOOL_DATA_LIMIT = 16 * 1024 * 1024;    # hexadecimal output value. This value should always be >= 64
my $PASSWORD_RECOVERY_TOOL_SUPPORT_PADDING_ATTACK  = 0;      # does the cracker support the AES-CBC padding attack (0 means no, 1 means yes)
my @PASSWORD_RECOVERY_TOOL_SUPPORTED_DECOMPRESSORS = (1, 2); # within this list we only need values ranging from 1 to 7
                                                             # i.e. SEVEN_ZIP_LZMA1_COMPRESSED to SEVEN_ZIP_DEFLATE_COMPRESSED
my @PASSWORD_RECOVERY_TOOL_SUPPORTED_PREPROCESSORS = ( 0 );  # BCJ2 can be "supported" by ignoring CRC
my $PASSWORD_RECOVERY_TOOL_SUPPORT_MULTIPLE_DECOMPRESSORS = 0; # does the cracker support more than one compressing algorithms for the same file (e.g. LZMA2 + LZMA1)
my $PASSWORD_RECOVERY_TOOL_SUPPORT_MULTIPLE_PREPROCESSORS = 0; # does the cracker support more than one preprocessing filters for the same file (e.g. BCJ + Delta)

# 7-zip specific stuff

my $LZMA2_MIN_COMPRESSED_LEN = 16; # the raw data (decrypted) needs to be at least: 3 + 1 + 1, header (start + size) + at least one byte of data + end
                                   # therefore we need to have at least one AES BLOCK (128 bits = 16 bytes)

# header

my $SEVEN_ZIP_MAGIC = "7z\xbc\xaf\x27\x1c";
my $SEVEN_ZIP_MAGIC_LEN = 6;                # fixed length of $SEVEN_ZIP_MAGIC

my $SEVEN_ZIP_END                = "\x00";
my $SEVEN_ZIP_HEADER             = "\x01";
my $SEVEN_ZIP_ARCHIVE_PROPERTIES = "\x02";
my $SEVEN_ZIP_ADD_STREAMS_INFO   = "\x03";
my $SEVEN_ZIP_MAIN_STREAMS_INFO  = "\x04";
my $SEVEN_ZIP_FILES_INFO         = "\x05";
my $SEVEN_ZIP_PACK_INFO          = "\x06";
my $SEVEN_ZIP_UNPACK_INFO        = "\x07";
my $SEVEN_ZIP_SUBSTREAMS_INFO    = "\x08";
my $SEVEN_ZIP_SIZE               = "\x09";
my $SEVEN_ZIP_CRC                = "\x0a";
my $SEVEN_ZIP_FOLDER             = "\x0b";
my $SEVEN_ZIP_UNPACK_SIZE        = "\x0c";
my $SEVEN_ZIP_NUM_UNPACK_STREAM  = "\x0d";
my $SEVEN_ZIP_EMPTY_STREAM       = "\x0e";
my $SEVEN_ZIP_EMPTY_FILE         = "\x0f";
my $SEVEN_ZIP_ANTI_FILE          = "\x10";
my $SEVEN_ZIP_NAME               = "\x11";
my $SEVEN_ZIP_CREATION_TIME      = "\x12";
my $SEVEN_ZIP_ACCESS_TIME        = "\x13";
my $SEVEN_ZIP_MODIFICATION_TIME  = "\x14";
my $SEVEN_ZIP_WIN_ATTRIBUTE      = "\x15";
my $SEVEN_ZIP_ENCODED_HEADER     = "\x17";
my $SEVEN_ZIP_START_POS          = "\x18";
my $SEVEN_ZIP_DUMMY              = "\x19";

my $SEVEN_ZIP_MAX_PROPERTY_TYPE  = 2 ** 30; # 1073741824
my $SEVEN_ZIP_NOT_EXTERNAL       = "\x00";
my $SEVEN_ZIP_EXTERNAL           = "\x01";
my $SEVEN_ZIP_ALL_DEFINED        = "\x01";
my $SEVEN_ZIP_FILE_NAME_END      = "\x00\x00";

# codec

my $SEVEN_ZIP_AES               = "\x06\xf1\x07\x01"; # all the following codec values are from CPP/7zip/Archive/7z/7zHeader.h

my $SEVEN_ZIP_LZMA1             = "\x03\x01\x01";
my $SEVEN_ZIP_LZMA2             = "\x21";
my $SEVEN_ZIP_PPMD              = "\x03\x04\x01";
my $SEVEN_ZIP_BCJ               = "\x03\x03\x01\x03";
my $SEVEN_ZIP_BCJ2              = "\x03\x03\x01\x1b";
my $SEVEN_ZIP_PPC               = "\x03\x03\x02\x05";
my $SEVEN_ZIP_ALPHA             = "\x03\x03\x03\x01";
my $SEVEN_ZIP_IA64              = "\x03\x03\x04\x01";
my $SEVEN_ZIP_ARM               = "\x03\x03\x05\x01";
my $SEVEN_ZIP_ARMT              = "\x03\x03\x07\x01";
my $SEVEN_ZIP_SPARC             = "\x03\x03\x08\x05";
my $SEVEN_ZIP_BZIP2             = "\x04\x02\x02";
my $SEVEN_ZIP_DEFLATE           = "\x04\x01\x08";
my $SEVEN_ZIP_DELTA             = "\x03";
my $SEVEN_ZIP_COPY              = "\x00";

# hash format

my $SEVEN_ZIP_HASH_SIGNATURE    = "\$7z\$";
my $SEVEN_ZIP_DEFAULT_POWER     = 19;
my $SEVEN_ZIP_DEFAULT_IV        = "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00";

my $SEVEN_ZIP_UNCOMPRESSED       =   0;
my $SEVEN_ZIP_LZMA1_COMPRESSED   =   1;
my $SEVEN_ZIP_LZMA2_COMPRESSED   =   2;
my $SEVEN_ZIP_PPMD_COMPRESSED    =   3;
my $SEVEN_ZIP_BZIP2_COMPRESSED   =   6;
my $SEVEN_ZIP_DEFLATE_COMPRESSED =   7;

my $SEVEN_ZIP_BCJ_PREPROCESSED   =   1;
my $SEVEN_ZIP_BCJ2_PREPROCESSED  =   2;
my $SEVEN_ZIP_PPC_PREPROCESSED   =   3;
my $SEVEN_ZIP_IA64_PREPROCESSED  =   4;
my $SEVEN_ZIP_ARM_PREPROCESSED   =   5;
my $SEVEN_ZIP_ARMT_PREPROCESSED  =   6;
my $SEVEN_ZIP_SPARC_PREPROCESSED =   7;
                                 #   8 conflicts with SEVEN_ZIP_TRUNCATED (128 == 0x80 == 8 << 4)
my $SEVEN_ZIP_DELTA_PREPROCESSED =   9;

my $SEVEN_ZIP_TRUNCATED          = 128; # (0x80 or 0b10000000)

my %SEVEN_ZIP_COMPRESSOR_NAMES   = (1 => "LZMA1", 2 => "LZMA2", 3 => "PPMD", 6 => "BZIP2", 7 => "DEFLATE",
                                    (1 << 4) => "BCJ", (2 << 4) => "BCJ2", (3 << 4) => "PPC", (4 << 4) => "IA64",
                                    (5 << 4) => "ARM", (6 << 4) => "ARMT", (7 << 4) => "SPARC", (9 << 4) => "DELTA");

#
# Helper functions
#

sub usage
{
  my $prog_name = shift;

  print STDERR "Usage: $prog_name <7-Zip file>...\n";
}

my $memory_buffer_read_offset = 0;

sub my_read
{
  my $input  = shift;
  my $length = shift;

  my $type_of_input = ref ($input);

  my $output_buffer = "";

  if ($type_of_input eq "GLOB")
  {
    read $input, $output_buffer, $length;
  }
  elsif ($type_of_input eq "HASH")
  {
    my $cur_file_handle = $$input{0}{'fh'};
    my $cur_file_number = $$input{0}{'num'};

    my $bytes_read = 0;

    while ($bytes_read != $length)
    {
      my $name  = $$input{$cur_file_number}{'name'};
      my $start = $$input{$cur_file_number}{'start'};
      my $size  = $$input{$cur_file_number}{'size'};

      my $cur_file_bytes_avail = ($start + $size) - $memory_buffer_read_offset;

      if ($cur_file_bytes_avail < 1)
      {
        print STDERR "ERROR: failed to get the correct file offsets of splitted archive file '$name'\n";

        exit (1);
      }

      my $total_bytes_to_read  = $length - $bytes_read;
      my $bytes_to_read = $total_bytes_to_read;

      if ($bytes_to_read > $cur_file_bytes_avail)
      {
        $bytes_to_read = $cur_file_bytes_avail;
      }

      # append the current bytes read from the file to the overall output buffer

      my $temp_output_buffer = "";

      my $bytes = read ($cur_file_handle, $temp_output_buffer, $bytes_to_read);

      $output_buffer .= $temp_output_buffer;

      if ($bytes != $bytes_to_read)
      {
        print STDERR "ERROR: could not read from splitted 7z file '$name'\n";

        exit (1);
      }

      $bytes_read += $bytes_to_read;
      $memory_buffer_read_offset += $bytes_to_read;

      # the following case only happens if we need to read across 2 or more files

      if ($bytes_read != $length)
      {
        # we exhausted the current file, move to the next one!

        close ($cur_file_handle);

        $cur_file_number++;

        if (! exists ($$input{$cur_file_number}))
        {
          my $name_prefix = get_splitted_archive_raw_name ($name);

          print STDERR "ERROR: could not open part #$cur_file_number of the splitted archive file '$name_prefix'\n";

          exit (1);
        }

        my $name = $$input{$cur_file_number}{'name'};

        if (! open ($cur_file_handle, "<$name"))
        {
          print STDERR "ERROR: could not open the splitted archive file '$name' for reading\n";

          exit (1);
        }

        $$input{0}{'fh'}  = $cur_file_handle;
        $$input{0}{'num'} = $cur_file_number;
      }
    }
  }
  else
  {
    $output_buffer = substr ($$input, $memory_buffer_read_offset, $length);

    $memory_buffer_read_offset += $length;
  }

  return $output_buffer;
}

sub my_tell
{
  my $input = shift;

  my $res = 0;

  my $type_of_input = ref ($input);

  if ($type_of_input eq "HASH")
  {
    $res = $memory_buffer_read_offset;
  }
  else
  {
    $res = tell ($input);
  }

  return $res;
}

sub my_seek
{
  my $input  = shift;
  my $offset = shift;
  my $whence = shift;

  my $res = 0;

  my $type_of_input = ref ($input);

  if ($type_of_input eq "HASH")
  {
    # get total number of files and total/accumulated file size

    my $number_of_files= 1;

    # we assume that $$input{1} exists (we did already check that beforehand)

    my $end = 0;

    while (exists ($$input{$number_of_files}))
    {
      $end = $$input{$number_of_files}{'start'} + $$input{$number_of_files}{'size'};

      $number_of_files++;
    }

    my $new_offset = 0;

    # absolute (from start)
    if ($whence == 0)
    {
      $new_offset = $offset;
    }
    # relative (depending on current position)
    elsif ($whence == 1)
    {
      $new_offset = $memory_buffer_read_offset + $offset;
    }
    # offset from the end of the file
    else
    {
      $new_offset = $end + $offset;
    }

    # sanity check

    if (($new_offset < 0) || ($new_offset > $end))
    {
      my $name = get_splitted_archive_raw_name ($$input{1}{'name'});

      print STDERR "ERROR: could not seek within the splitted archive '$name'\n";

      exit (1);
    }

    $memory_buffer_read_offset = $new_offset;

    # check if the correct file is open
    # 1. determine the correct file
    # 2. if the "incorrect" file is open, close it and open the correct one

    my $cur_file_number = 1;
    my $file_was_found  = 0;

    my $start = 0;
    my $size  = 0;

    while (exists ($$input{$cur_file_number}))
    {
      $start = $$input{$cur_file_number}{'start'};
      $size  = $$input{$cur_file_number}{'size'};

      my $end = $start + $size;

      if ($memory_buffer_read_offset >= $start)
      {
        if ($memory_buffer_read_offset < $end)
        {
          $file_was_found = 1;

          last;
        }
      }

      $cur_file_number++;
    }

    if ($file_was_found == 0)
    {
      my $name = get_splitted_archive_raw_name ($$input{1}{'name'});

      print STDERR "ERROR: could not read the splitted archive '$name' (maybe some parts are missing?)\n";

      exit (1);
    }

    if ($$input{0}{'num'} != $cur_file_number)
    {
      # if we enter this block, we definitely need to "change" to another file

      close ($$input{0}{'fh'});

      my $name = $$input{$cur_file_number}{'name'};

      my $seven_zip_file;

      if (! open ($seven_zip_file, "<$name"))
      {
        print STDERR "ERROR: could not open the file '$name' for reading\n";

        exit (1);
      }

      $$input{0}{'fh'}  = $seven_zip_file;
      $$input{0}{'num'} = $cur_file_number;
    }

    # always seek w/ absolute positions within the splitted part!
    $res = seek ($$input{0}{'fh'}, $memory_buffer_read_offset - $start, 0);
  }
  else
  {
    $res = seek ($input, $offset, $whence);
  }

  return $res;
}

sub get_uint32
{
  my $fp = shift;

  my $bytes = my_read ($fp, 4);

  return (0, 0) if (length ($bytes) != 4);

  my $num = unpack ("L", $bytes);

  return $num;
}

sub get_uint64
{
  my $fp = shift;

  my $bytes = my_read ($fp, 8);

  return (0, 0) if (length ($bytes) != 8);

  my ($uint1, $uint2) = unpack ("LL<", $bytes);

  my $num = $uint2 << 32 | $uint1;

  return $bytes, $num;
}

sub read_number
{
  my $fp = shift;

  my $b = ord (my_read ($fp, 1));

  if (($b & 0x80) == 0)
  {
    return $b;
  }

  my $value = ord (my_read ($fp, 1));

  for (my $i = 1; $i < 8; $i++)
  {
    my $mask = 0x80 >> $i;

    if (($b & $mask) == 0)
    {
      my $high = $b & ($mask - 1);

      $value |= ($high << ($i * 8));

      return $value;
    }

    my $next = ord (my_read ($fp, 1));

    $value |= ($next << ($i * 8));
  }

  return $value;
}

sub num_to_id
{
  my $num = shift;

  # special case:

  return "\x00" if ($num == 0);

  # normal case:

  my $id = "";

  while ($num > 0)
  {
    my $value = $num & 0xff;

    $id = chr ($value) . $id;

    $num >>= 8;
  }

  return $id;
}

sub read_id
{
  my $fp = shift;

  my $id;

  my $num = read_number ($fp);

  # convert number to their ASCII code correspondent byte

  return num_to_id ($num);
}

sub get_boolean_vector
{
  my $fp = shift;

  my $number_items = shift;

  my @booleans;

  # get the values

  my $v = 0;
  my $mask = 0;

  for (my $i = 0; $i < $number_items; $i++)
  {
    if ($mask == 0)
    {
      my $byte = my_read ($fp, 1);

      $v = ord ($byte);
      $mask = 0x80;
    }

    my $val = ($v & $mask) != 0;

    push (@booleans, $val);

    $mask >>= 1;
  }

  return @booleans;
}

sub get_boolean_vector_check_all
{
  my $fp = shift;

  my $number_items = shift;

  my @booleans;

  # check first byte to see if all are defined

  my $all_defined = my_read ($fp, 1);

  if ($all_defined eq $SEVEN_ZIP_ALL_DEFINED)
  {
    @booleans = (1) x $number_items;
  }
  else
  {
    @booleans = get_boolean_vector ($fp, $number_items);
  }

  return @booleans;
}

sub is_supported_seven_zip_file
{
  my $fp = shift;

  my $magic_len = length ($SEVEN_ZIP_MAGIC);

  my $signature = my_read ($fp, $magic_len);

  return $signature eq $SEVEN_ZIP_MAGIC;
}

sub get_decoder_properties
{
  my $attributes = shift;

  my $salt_len;
  my $salt_buf;
  my $iv_len;
  my $iv_buf;
  my $number_cycles_power;

  # set some default values

  $salt_len = 0;
  $salt_buf = "";
  $iv_len = length ($SEVEN_ZIP_DEFAULT_IV);
  $iv_buf = $SEVEN_ZIP_DEFAULT_IV;
  $number_cycles_power = $SEVEN_ZIP_DEFAULT_POWER;

  # the most important information is encoded in first and second byte
  # i.e. the salt/iv length, number cycle power

  my $offset = 0;

  my $first_byte = substr ($attributes, 0, 1);
  $first_byte = ord ($first_byte);

  $offset++;

  $number_cycles_power = $first_byte & 0x3f;

  if (($first_byte & 0xc0) == 0)
  {
    return ($salt_len, $salt_buf, $iv_len, $iv_buf, $number_cycles_power);
  }

  $salt_len = ($first_byte >> 7) & 1;
  $iv_len   = ($first_byte >> 6) & 1;

  # combine this info with the second byte

  my $second_byte = substr ($attributes, 1, 1);
  $second_byte = ord ($second_byte);

  $offset++;

  $salt_len += ($second_byte >> 4);
  $iv_len   += ($second_byte & 0x0f);

  $salt_buf = substr ($attributes, $offset, $salt_len);

  $offset += $salt_len;

  $iv_buf = substr ($attributes, $offset, $iv_len);

  # pad the iv with zeros

  my $iv_max_length = 16;

  $iv_buf .= "\x00" x $iv_max_length;
  $iv_buf = substr ($iv_buf, 0, $iv_max_length);

  return ($salt_len, $salt_buf, $iv_len, $iv_buf, $number_cycles_power);
}

sub get_digest
{
  my $index = shift;

  my $unpack_info = shift;
  my $substreams_info = shift;

  my $digest;

  my $digests_unpack_info = $unpack_info->{'digests'};
  my $digests_substreams_info = $substreams_info->{'digests'};

  my $use_unpack_info = 0;
  my $use_substreams_info = 0;

  if (defined ($digests_unpack_info))
  {
    my $digests_unpack_info_size = 0;

    if (@$digests_unpack_info)
    {
      $digests_unpack_info_size = scalar (@$digests_unpack_info);
    }

    if ($index < $digests_unpack_info_size)
    {
      if (ref (@$digests_unpack_info[$index]) eq "HASH")
      {
        $use_unpack_info = 1;
      }
    }
  }

  if (defined ($digests_substreams_info))
  {
    my $digests_substreams_info_size = 0;

    if (@$digests_substreams_info)
    {
      $digests_substreams_info_size = scalar (@$digests_substreams_info);
    }

    if ($index < $digests_substreams_info_size)
    {
      if (ref (@$digests_substreams_info[$index]) eq "HASH")
      {
        $use_substreams_info = 1;
      }
    }
  }

  if ($use_unpack_info == 1)
  {
    $digest = @$digests_unpack_info[$index];
  }
  elsif ($use_substreams_info == 1)
  {
    $digest = @$digests_substreams_info[$index];
  }

  return $digest;
}

sub has_encrypted_header
{
  my $folder = shift;

  my $encrypted;

  # get first coder

  my $coders = $folder->{'coders'};

  # get attributes of the first coder

  my $attributes = @$coders[0]->{'codec_id'};

  if ($attributes eq $SEVEN_ZIP_AES)
  {
    $encrypted = 1;
  }
  else
  {
    $encrypted = 0;
  }

  return $encrypted;
}

sub lzma_properties_decode
{
  my $attributes = shift;

  my $lclppb;

  $lclppb = substr ($attributes, 0, 1);

  my @data;

  #data[0] is the lclppb value

  $data[1] = ord (substr ($attributes, 1, 1));
  $data[2] = ord (substr ($attributes, 2, 1));
  $data[3] = ord (substr ($attributes, 3, 1));
  $data[4] = ord (substr ($attributes, 4, 1));

  my $dict_size = $data[1] | $data[2] << 8 | $data[3] << 16 | $data[4] << 24;

  if ($dict_size < LZMA_DICT_SIZE_MIN)
  {
    $dict_size = LZMA_DICT_SIZE_MIN;
  }

  my $d = ord ($lclppb);

  my $lc = int ($d % 9);
     $d  = int ($d / 9);
  my $pb = int ($d / 5);
  my $lp = int ($d % 5);

  return ($lclppb, $dict_size, $lc, $pb, $lp);
}

sub lzma_alone_header_field_encode
{
  my $num = shift;
  my $length = shift;

  my $value;

  my $length_doubled = $length * 2;
  my $big_endian_val = pack ("H*", sprintf ("%0${length_doubled}x", $num));

  # what follows is just some easy way to convert endianess (there might be better ways of course)

  $value = "";

  for (my $i = $length - 1; $i >= 0; $i--)
  {
    $value .= substr ($big_endian_val, $i, 1);
  }

  return $value;
}

sub show_empty_streams_info_warning
{
  my $file_path = shift;

  print STDERR "WARNING: the file '" . $file_path . "' does not contain any meaningful data (the so-called streams info), it might only contain a list of empty files.\n";
}

sub fill_additional_attribute_list
{
  my $coder            = shift;
  my $file_path        = shift;
  my $coder_attributes = shift;

  my $error = 0;

  my $codec_id = $$coder->{'codec_id'};

  my $type = $SEVEN_ZIP_UNCOMPRESSED;

  my $is_preprocessor = 0;

  if ($codec_id eq $SEVEN_ZIP_LZMA1)
  {
    $type = $SEVEN_ZIP_LZMA1_COMPRESSED;
  }
  elsif ($codec_id eq $SEVEN_ZIP_LZMA2)
  {
    $type = $SEVEN_ZIP_LZMA2_COMPRESSED;
  }
  elsif ($codec_id eq $SEVEN_ZIP_PPMD)
  {
    $type = $SEVEN_ZIP_PPMD_COMPRESSED;
  }
  elsif ($codec_id eq $SEVEN_ZIP_BZIP2)
  {
    $type = $SEVEN_ZIP_BZIP2_COMPRESSED;
  }
  elsif ($codec_id eq $SEVEN_ZIP_DEFLATE)
  {
    $type = $SEVEN_ZIP_DEFLATE_COMPRESSED;
  }
  elsif ($codec_id eq $SEVEN_ZIP_COPY)
  {
    return 0; # don't add it to our coder_attributes list, it's a NO-OP
  }
  elsif ($codec_id eq $SEVEN_ZIP_BCJ)
  {
    $type = $SEVEN_ZIP_BCJ_PREPROCESSED;

    $is_preprocessor = 1;
  }
  elsif ($codec_id eq $SEVEN_ZIP_BCJ2)
  {
    $type = $SEVEN_ZIP_BCJ2_PREPROCESSED;

    $is_preprocessor = 1;
  }
  elsif ($codec_id eq $SEVEN_ZIP_PPC)
  {
    $type = $SEVEN_ZIP_PPC_PREPROCESSED;

    $is_preprocessor = 1;
  }
  elsif ($codec_id eq $SEVEN_ZIP_IA64)
  {
    $type = $SEVEN_ZIP_IA64_PREPROCESSED;

    $is_preprocessor = 1;
  }
  elsif ($codec_id eq $SEVEN_ZIP_ARM)
  {
    $type = $SEVEN_ZIP_ARM_PREPROCESSED;

    $is_preprocessor = 1;
  }
  elsif ($codec_id eq $SEVEN_ZIP_ARMT)
  {
    $type = $SEVEN_ZIP_ARMT_PREPROCESSED;

    $is_preprocessor = 1;
  }
  elsif ($codec_id eq $SEVEN_ZIP_SPARC)
  {
    $type = $SEVEN_ZIP_SPARC_PREPROCESSED;

    $is_preprocessor = 1;
  }
  elsif ($codec_id eq $SEVEN_ZIP_DELTA)
  {
    $type = $SEVEN_ZIP_DELTA_PREPROCESSED;

    $is_preprocessor = 1;
  }
  else
  {
    print STDERR "WARNING: unsupported coder with codec id '0x" . unpack ("H*", $codec_id) . "' in file '" . $file_path . "' found.\n";

    $error = 1;

    return $error;
  }

  my $attributes = undef;

  if ($type != $SEVEN_ZIP_UNCOMPRESSED)
  {
    if (defined ($$coder->{'attributes'}))
    {
      $attributes = unpack ("H*", $$coder->{'attributes'});
    }
  }

  my %item = ('type'            => $type,
              'is_preprocessor' => $is_preprocessor,
              'attributes'      => $attributes);

  push (@$coder_attributes, \%item);

  return $error;
}

sub check_attributes
{
  my $attributes     = shift;
  my $is_truncated   = shift;
  my $file_path      = shift;
  my $padding_attack = shift;
  my $data_len       = shift;
  my $warning_shown  = shift;

  my $additional_attributes = "";
  my $error = 0;

  # Defaults:

  my $type_of_compression  = $SEVEN_ZIP_UNCOMPRESSED;
  my $type_of_preprocessor = $SEVEN_ZIP_UNCOMPRESSED;

  my $compression_attributes  = "";
  my $preprocessor_attributes = "";

  my $codec_count        = 0;
  my $compressor_count   = 0;
  my $preprocessor_count = 0;

  my $show_warning = 0;

  my $steps_involved = "";

  foreach my $attribute (@$attributes)
  {
    my $is_preprocessor = $attribute->{'is_preprocessor'};

    my $cur_type = $attribute->{'type'};

    my $attr = "";

    if (defined ($attribute->{'attributes'}))
    {
      $attr = $attribute->{'attributes'};
    }

    if ($is_preprocessor == 0)
    {
      if (grep (/^$cur_type$/, @PASSWORD_RECOVERY_TOOL_SUPPORTED_DECOMPRESSORS) == 0)
      {
        $show_warning = 1;
      }

      $compressor_count++;

      if ($compressor_count == 1)
      {
        $type_of_compression = $cur_type;

        if ($preprocessor_count == 0)
        {
          $compression_attributes = $attr;
        }
        else # special case: preprocessor after compressing (unlikely)
        {
          $compression_attributes = "," . (($cur_type << 4) + $codec_count) . "_" . $attr;
        }
      }
      else
      {
        $compression_attributes .= "," . (($cur_type << 4) + $codec_count) . "_" . $attr;
      }

      # cosmetic (warning message):

      if (length ($steps_involved) > 0)
      {
        $steps_involved .= ", ";
      }

      $steps_involved .= "decompressed using " . $SEVEN_ZIP_COMPRESSOR_NAMES{$cur_type};
    }
    else # if ($is_preprocessor == 1)
    {
      if (grep (/^$cur_type$/, @PASSWORD_RECOVERY_TOOL_SUPPORTED_PREPROCESSORS) == 0)
      {
        $show_warning = 1;
      }

      $preprocessor_count++;

      if ($preprocessor_count == 1)
      {
        $type_of_preprocessor = $cur_type;

        $preprocessor_attributes = $attr;
      }
      else
      {
        $preprocessor_attributes .= "," . (($cur_type << 4) + $codec_count) . "_" . $attr;
      }

      # cosmetic (warning message):

      if (length ($steps_involved) > 0)
      {
        $steps_involved .= ", ";
      }

      $steps_involved .= "processed using " . $SEVEN_ZIP_COMPRESSOR_NAMES{$cur_type << 4};
    }

    $codec_count++;

    if ($codec_count >= 16)
    {
      print STDERR "WARNING: unsupported amount of compression algorithms/preprocessing filters for the file '". $file_path . "',\n";

      $error = 1;

      last;
    }
  }

  # cosmetic: replace the last "," with an "and"

  my $last_comma_in_steps = rindex ($steps_involved, ",");

  if ($last_comma_in_steps >= 0)
  {
    $steps_involved = substr ($steps_involved, 0, $last_comma_in_steps) . " and " .
                      substr ($steps_involved, $last_comma_in_steps + 2);
  }

  # show a warning if the decompression algorithm is currently not supported by the cracker

  if (($SHOW_UNSUPPORTED_CODER_WARNING == 0) ||
      ($show_warning  == 0)                  ||
      ($is_truncated  == 1)                  ||
      ($warning_shown == 1))
  {
    # no warning(s) needed
  }
  else
  {
    print STDERR "WARNING: to correctly verify the CRC checksum of the data contained within the file '". $file_path . "',\n";
    print STDERR "the data must be " . $steps_involved . ".\n";
    print STDERR "\n";
    print STDERR "$PASSWORD_RECOVERY_TOOL_NAME currently does not support this particular decompression algorithm(s) or preprocessing filter(s).\n";
    print STDERR "\n";

    if ($padding_attack == 1) # is padding attack even possible
    {
      print STDERR "INFO: However there is also some good news in this particular case.\n";
      print STDERR "Since AES-CBC is used by the 7z algorithm and the data length of this file allows a padding attack,\n";
      print STDERR "the password recovery tool might be able to use that to verify the correctness of password candidates.\n";
      print STDERR "By using this attack there might of course be a higher probability of false positives.\n";
      print STDERR "\n";

      if ($PASSWORD_RECOVERY_TOOL_SUPPORT_PADDING_ATTACK == 0)
      {
        print STDERR "$PASSWORD_RECOVERY_TOOL_NAME currently does not support padding attacks.\n";
        print STDERR "\n";
      }
    }
    elsif ($type_of_compression == $SEVEN_ZIP_LZMA2_COMPRESSED) # this special case should only work for LZMA2
    {
      if ($data_len <= $LZMA2_MIN_COMPRESSED_LEN)
      {
        print STDERR "INFO: it might still be possible to crack the password of this archive since the data part seems\n";
        print STDERR "to be very short and therefore it might use the LZMA2 uncompressed chunk feature\n";
        print STDERR "\n";
      }
    }
  }

  # special case: all compressors/filters are supported, but cracker does NOT support combinations:

  if ($compressor_count > 1)
  {
    if ($PASSWORD_RECOVERY_TOOL_SUPPORT_MULTIPLE_DECOMPRESSORS == 0)
    {
      if (($warning_shown == 0) &&
          ($show_warning  == 0))
      {
        print STDERR "WARNING: $PASSWORD_RECOVERY_TOOL_NAME does not currently support combining/cascading multiple decompression algorithms\n";
        print STDERR "\n";
      }

      $show_warning = 1;
    }
  }

  if ($preprocessor_count > 1)
  {
    if ($PASSWORD_RECOVERY_TOOL_SUPPORT_MULTIPLE_PREPROCESSORS == 0)
    {
      if (($warning_shown == 0) &&
          ($show_warning  == 0))
      {
        print STDERR "WARNING: $PASSWORD_RECOVERY_TOOL_NAME does not currently support combining/cascading multiple preprocessing filters\n";
        print STDERR "\n";
      }

      $show_warning = 1;
    }
  }

  $additional_attributes = $compression_attributes;

  if (length ($preprocessor_attributes) > 0) # special case: we need both attributes
  {
    $additional_attributes .= "\$" . $preprocessor_attributes;
  }

  my $type_of_data = $SEVEN_ZIP_UNCOMPRESSED; # this variable will hold the "number" after the "$7z$" hash signature

  if ($is_truncated == 1)
  {
    $type_of_data = $SEVEN_ZIP_TRUNCATED; # note: this means that we neither need the crc_len, nor the coder attributes
  }
  else
  {
    $type_of_data = ($type_of_preprocessor << 4) | $type_of_compression;
  }

  return ($type_of_data, $additional_attributes, $show_warning, $error);
}

sub extract_hash_from_archive
{
  my $fp = shift;
  my $archive = shift;
  my $file_path = shift;

  my $hash_buf = "";

  # check if everything is defined/initialized
  # and retrieve the single "objects"

  return undef unless (defined ($archive));

  my $parsed_header = $archive->{'parsed_header'};
  return undef unless (defined ($parsed_header));

  my $signature_header = $archive->{'signature_header'};
  return undef unless (defined ($signature_header));

  my $streams_info = $parsed_header->{'streams_info'};

  if (! defined ($streams_info))
  {
    show_empty_streams_info_warning ($file_path);

    return undef;
  }

  my $unpack_info = $streams_info->{'unpack_info'};
  return undef unless (defined ($unpack_info));

  my $substreams_info = $streams_info->{'substreams_info'};

  my $digests = $unpack_info->{'digests'};
  return undef unless (defined ($digests));

  my $folders = $unpack_info->{'folders'};
  return undef unless (defined ($folders));

  my $pack_info = $streams_info->{'pack_info'};
  return undef unless (defined ($pack_info));

  # init file seek values

  my $position_after_header = $signature_header->{'position_after_header'};
  my $position_pack = $pack_info->{'pack_pos'};
  my $current_seek_position = $position_after_header + $position_pack;

  #
  # start:
  #

  # get first folder/coder

  my $folder_id = 0;

  my $folder = @$folders[$folder_id];

  my $number_coders = $folder->{'number_coders'};

  # check if header is encrypted

  my $has_encrypted_header = 0;

  if ($number_coders > 1)
  {
    $has_encrypted_header = 0;
  }
  else
  {
    $has_encrypted_header = has_encrypted_header ($folder);
  }

  # get the first coder

  my $coder_index = 0;

  my $coder = $folder->{'coders'}[$coder_index];
  return undef unless (defined ($coder));

  my $codec_id = $coder->{'codec_id'};

  # set index and seek to postition

  my $pack_size_index   = 0;
  my $unpack_size_index = 0;
  my $folder_index      = 0;

  my_seek ($fp, $current_seek_position, 0);

  # if it is lzma compressed, we need to decompress it first

  if ($codec_id eq $SEVEN_ZIP_LZMA1)
  {
    # get the sizes

    # my $unpack_size = $unpack_info->{'unpack_sizes'}[$unpack_size_index];
    my $unpack_size = get_folder_aes_unpack_size ($unpack_info, $folder_index);

    my $data_len = $pack_info->{'pack_sizes'}[$pack_size_index];

    # get the data

    my $data = my_read ($fp, $data_len);

    # lzma "header" stuff

    my $attributes = $coder->{'attributes'};

    my ($property_lclppb, $dict_size, $lc, $pb, $lp) = lzma_properties_decode ($attributes);

    return undef unless (length ($property_lclppb) == 1);

    # the alone-format header is defined like this:
    #
    #   +------------+----+----+----+----+--+--+--+--+--+--+--+--+
    #   | Properties |  Dictionary Size  |   Uncompressed Size   |
    #   +------------+----+----+----+----+--+--+--+--+--+--+--+--+
    #

    my $decompressed_header = "";

    # we loop over this code section max. 2 times to try two variants of headers (with the correct/specific values and with default values)

    for (my $try_number = 1; $try_number <= 2; $try_number++)
    {
      my ($dict_size_encoded, $uncompressed_size_encoded);
      my $lz = new Compress::Raw::Lzma::AloneDecoder (AppendOutput => 1);

      if ($try_number == 1)
      {
        $dict_size_encoded         = lzma_alone_header_field_encode ($dict_size,   4); # 4 bytes (the "Dictionary Size" field), little endian
        $uncompressed_size_encoded = lzma_alone_header_field_encode ($unpack_size, 8); # 8 bytes (the "Uncompressed Size" field), little endian
      }
      else
      {
        # this is the fallback case (using some default values):

        $dict_size_encoded         = pack ("H*", "00008000");         # "default" dictionary size (2^23 = 0x00800000)
        $uncompressed_size_encoded = pack ("H*", "ffffffffffffffff"); # means: unknown uncompressed size
      }

      my $lzma_alone_format_header = $property_lclppb . $dict_size_encoded . $uncompressed_size_encoded;

      my $lzma_header = $lzma_alone_format_header . $data;

      my $status = $lz->code ($lzma_header, $decompressed_header);

      if (length ($status) > 0)
      {
        if ($try_number == 2)
        {
          if ($status != LZMA_STREAM_END)
          {
            print STDERR "WARNING: the LZMA header decompression for the file '" . $file_path . "' failed with status: '" . $status . "'\n";

            if ($status eq "Data is corrupt")
            {
              print STDERR "\n";
              print STDERR "INFO: for some reasons, for large LZMA buffers, we sometimes get a 'Data is corrupt' error.\n";
              print STDERR "      This is a known issue of this tool and needs to be investigated.\n";

              print STDERR "\n";
              print STDERR "      The problem might have to do with this small paragraph hidden in the 7z documentation (quote):\n";
              print STDERR "      'The reference LZMA Decoder ignores the value of the \"Corrupted\" variable.\n";
              print STDERR "       So it continues to decode the stream, even if the corruption can be detected\n";
              print STDERR "       in the Range Decoder. To provide the full compatibility with output of the\n";
              print STDERR "       reference LZMA Decoder, another LZMA Decoder implementation must also\n";
              print STDERR "       ignore the value of the \"Corrupted\" variable.'\n";
              print STDERR "\n";
              print STDERR "      (taken from the DOC/lzma-specification.txt file of the 7z-SDK: see for instance:\n";
              print STDERR "       https://github.com/jljusten/LZMA-SDK/blob/master/DOC/lzma-specification.txt#L343-L347)\n";
            }

            return undef;
          }
        }
      }

      last if (length ($decompressed_header) > 0); # if we got some output it seems that it worked just fine
    }

    return undef unless (length ($decompressed_header) > 0);

    # in theory we should also check that the length is correct
    # return undef unless (length ($decompressed_header) == $unpack_size);

    # check the decompressed 7zip header

    $memory_buffer_read_offset = 0; # decompressed_header is a new memory buffer (which uses a offset to speed things up)

    my $id = read_id (\$decompressed_header);

    return undef unless ($id eq $SEVEN_ZIP_HEADER);

    my $header = read_seven_zip_header (\$decompressed_header);

    # override the "old" archive object

    $archive = {
      "signature_header" => $signature_header,
      "parsed_header" => $header
    };

    $parsed_header = $archive->{'parsed_header'};
    return "" unless (defined ($parsed_header));

    # this didn't change at all
    # $signature_header = $archive->{'signature_header'};
    # return undef unless (defined ($signature_header));

    $streams_info = $parsed_header->{'streams_info'};

    if (! defined ($streams_info))
    {
      show_empty_streams_info_warning ($file_path);

      return "";
    }

    $unpack_info = $streams_info->{'unpack_info'};
    return "" unless (defined ($unpack_info));

    $substreams_info = $streams_info->{'substreams_info'};

    $digests = $unpack_info->{'digests'};
    return "" unless (defined ($digests));

    $folders = $unpack_info->{'folders'};
    return "" unless (defined ($folders));

    my $number_folders = $unpack_info->{'number_folders'};

    $pack_info = $streams_info->{'pack_info'};
    return "" unless (defined ($pack_info));

    # loop over all folders/coders to check if we find an AES encrypted stream

    $position_pack = $pack_info->{'pack_pos'};
    $current_seek_position = $position_after_header + $position_pack; # reset the seek position

    for (my $folder_pos = 0; $folder_pos < $number_folders; $folder_pos++)
    {
      $folder_index = $folder_pos;

      $folder = @$folders[$folder_pos];
      last unless (defined ($folder));

      $number_coders = $folder->{'number_coders'};

      my $num_pack_sizes = scalar (@{$pack_info->{'pack_sizes'}});

      for (my $coder_pos = 0; $coder_pos < $number_coders; $coder_pos++)
      {
        $coder = $folder->{'coders'}[$coder_pos];
        last unless (defined ($coder));

        $coder_index = $coder_pos;

        $codec_id = $coder->{'codec_id'};

        # we stop after first AES found, but in theory we could also deal
        # with several different AES streams (in that case we would need
        # to print several hash buffers, but this is a very special case)

        last if ($codec_id eq $SEVEN_ZIP_AES);
      }

      last if ($codec_id eq $SEVEN_ZIP_AES);

      last unless (defined ($coder));

      # ELSE: update seek position and index:

      my $sum_packed_streams = $unpack_info->{'folders'}[$folder_pos]->{'sum_packed_streams'};

      for (my $packed_stream = 0; $packed_stream < $sum_packed_streams; $packed_stream++)
      {
        my $pack_size = $pack_info->{'pack_sizes'}[$pack_size_index + $packed_stream];

        $current_seek_position += $pack_size;
      }

      $pack_size_index += $sum_packed_streams;

      $unpack_size_index += $substreams_info->{'unpack_stream_numbers'}[$folder_pos];
    }

    # we unfortunately can't do anything if no AES encrypted data was found

    if ($codec_id ne $SEVEN_ZIP_AES)
    {
      print STDERR "WARNING: no AES data found in the 7z file '" . $file_path . "'\n";

      return "";
    }
  }
  elsif ($codec_id eq $SEVEN_ZIP_LZMA2)
  {
    print STDERR "WARNING: lzma2 compression found within '" . $file_path . "' is currently not supported, ";
    print STDERR "but could be probably added easily\n";

    return "";
  }
  elsif ($codec_id ne $SEVEN_ZIP_AES)
  {
    print STDERR "WARNING: unsupported coder with codec id '0x" . unpack ("H*", $codec_id) . "' in file '" . $file_path . "' found.\n";
    print STDERR "If you think this codec method from DOC/Methods.txt of the 7-Zip source code ";
    print STDERR "should be supported, please file a problem report/feature request\n";

    return "";
  }

  #
  # finally: fill hash_buf
  #

  # first get the data with help of pack info

  my $unpack_size = get_folder_aes_unpack_size ($unpack_info, $folder_index);

  my $data_len = $pack_info->{'pack_sizes'}[$pack_size_index];

  # reset the file pointer to the position after signature header and get the data

  my_seek ($fp, $current_seek_position, 0);

  # get remaining hash info (iv, number cycles power)

  my $digest = get_digest ($unpack_size_index, $unpack_info, $substreams_info);

  return "" unless ((defined ($digest)) && ($digest->{'defined'} == 1));

  my $attributes = $coder->{'attributes'};

  my ($salt_len, $salt_buf, $iv_len, $iv_buf, $number_cycles_power) = get_decoder_properties ($attributes);

  my $crc = $digest->{'crc'};

  # special case: we can truncate the data_len and use 32 bytes in total for both iv + data (last 32 bytes of data)

  my $is_truncated = 0;
  my $padding_attack_possible = 0;

  my $data;

  if ($has_encrypted_header == 0)
  {
    my $length_difference = $data_len - $unpack_size;

    if ($length_difference > 3)
    {
      if ($data_len > ($PASSWORD_RECOVERY_TOOL_DATA_LIMIT / 2))
      {
        if ($PASSWORD_RECOVERY_TOOL_SUPPORT_PADDING_ATTACK == 1)
        {
          my_seek ($fp, $data_len - 32, 1);

          $iv_buf = my_read ($fp, 16);
          $iv_len = 16;

          $data = my_read ($fp, 16);
          $data_len = 16;

          $unpack_size %= 16;

          $is_truncated = 1;
        }
      }

      $padding_attack_possible = 1;
    }
  }

  my @coder_attributes = (); # type, is_preprocessor, attributes

  for (my $coder_pos = $coder_index + 1; $coder_pos < $number_coders; $coder_pos++)
  {
    $coder = $folder->{'coders'}[$coder_pos];
    last unless (defined ($coder));

    my $is_error = fill_additional_attribute_list (\$coder, $file_path, \@coder_attributes);

    return "" if ($is_error == 1);
  }

  my ($type_of_data,
      $additional_attributes,
      $codec_warning_shown,
      $attribute_error) = check_attributes (\@coder_attributes,
                                            $is_truncated,
                                            $file_path,
                                            $padding_attack_possible,
                                            $data_len,
                                            0);

  return "" if ($attribute_error == 1);

  my $found_stream_without_warning = 0;

  if ($codec_warning_shown == 0)
  {
    $found_stream_without_warning = 1;
  }

  my $crc_len = 0;

  if (($type_of_data != $SEVEN_ZIP_UNCOMPRESSED) && ($type_of_data != $SEVEN_ZIP_TRUNCATED))
  {
    if (scalar ($substreams_info->{'unpack_sizes'}) > $unpack_size_index)
    {
      $crc_len = $substreams_info->{'unpack_sizes'}[$unpack_size_index];
    }
  }

  if (! defined ($data))
  {
    if (($type_of_data != $SEVEN_ZIP_UNCOMPRESSED) && ($type_of_data != $SEVEN_ZIP_TRUNCATED))
    {
      if ($ANALYZE_ALL_STREAMS_TO_FIND_SHORTEST_DATA_BUF == 1)
      {
        my $number_file_indices = scalar (@{$substreams_info->{'unpack_sizes'}});
        my $number_streams      = scalar (@{$substreams_info->{'unpack_stream_numbers'}});
        my $number_pack_info    = scalar (@{$pack_info->{'pack_sizes'}}); # same as $pack_info->{'number_pack_streams'}
        my $number_folders      = scalar (@{$folders}); # same as $unpack_info->{'number_folders'}

        # check if there is a stream with a smaller first file than the first file of the first stream
        # (this is just a clever approach to produce shorter hashes)

        my $next_file_index      = 0;
        my $next_pack_size_index = 0;
        my $next_data_offset     = 0;

        my $data_offset = 0;

        # sanity checks (otherwise we might overflow):

        if ($number_pack_info < $number_streams) # should never happen (they should be equal)
        {
          $number_streams = $number_pack_info;
        }

        if ($number_folders < $number_streams) # should never happen (they should be equal)
        {
          $number_streams = $number_folders;
        }

        for (my $stream_index = 0; $stream_index < $number_streams; $stream_index++)
        {
          my $file_index = $next_file_index;

          last if ($file_index >= $number_file_indices); # should never happen

          $next_file_index += $substreams_info->{'unpack_stream_numbers'}[$stream_index];

          my $length_first_file = $substreams_info->{'unpack_sizes'}[$file_index];


          my $data_offset_tmp = $next_data_offset;

          my $pack_size_index = $next_pack_size_index;

          last if ($pack_size_index >= $number_pack_info); # should never happen

          my $sum_packed_streams = $unpack_info->{'folders'}[$stream_index]->{'sum_packed_streams'};

          $next_pack_size_index += $sum_packed_streams;

          my $length_compressed = 0;

          for (my $packed_stream = 0; $packed_stream < $sum_packed_streams; $packed_stream++)
          {
            $length_compressed += $pack_info->{'pack_sizes'}[$pack_size_index + $packed_stream];
          }

          $next_data_offset += $length_compressed;


          if ($SHOW_LIST_OF_ALL_STREAMS == 1)
          {
            print STDERR sprintf ("DEBUG: new stream found with first file consisting of %9d bytes of %10d bytes total stream length\n", $length_first_file, $length_compressed);
          }

          if ($length_first_file < $crc_len)
          {
            my $digest = get_digest ($file_index, $unpack_info, $substreams_info);

            next unless ((defined ($digest)) && ($digest->{'defined'} == 1));

            # get new AES settings (salt, iv, costs):

            my $coders = @$folders[$stream_index]->{'coders'};

            my $number_coders = @$folders[$stream_index]->{'number_coders'};

            my $aes_coder_index = 0;
            my $aes_coder_found = 0;

            my @coder_attributes = ();

            for (my $coders_index = 0; $coders_index < $number_coders; $coders_index++)
            {
              my $coder = @$coders[$coders_index];
              last unless (defined ($coder));

              my $codec_id = $coder->{'codec_id'};

              if ($codec_id eq $SEVEN_ZIP_AES)
              {
                $aes_coder_index = $coders_index;

                $aes_coder_found = 1;
              }
              else
              {
                my $is_error = fill_additional_attribute_list (\$coder, $file_path, \@coder_attributes);

                return "" if ($is_error == 1);
              }
            }

            next unless ($aes_coder_found == 1);

            if ($found_stream_without_warning == 1)
            {
              # special case: don't show any warnings if other streams worked, because we choose
              # both the shortest stream AND the one that is supported by the cracker

              $codec_warning_shown = 1;
            }

            my ($tmp_type_of_data,
                $tmp_additional_attributes,
                $tmp_codec_warning_shown,
                $attribute_error) = check_attributes (\@coder_attributes,
                                                   $is_truncated,
                                                   $file_path,
                                                   $padding_attack_possible,
                                                   $data_len,
                                                   $codec_warning_shown);

            # very special case: *first* stream that has no codec errors after at least one
            # stream/file with unsupported compression/filter settings/methods

            if (($found_stream_without_warning == 0) &&
                ($attribute_error              == 0) &&
                ($tmp_codec_warning_shown      == 0) &&
                ($codec_warning_shown          == 1))
            {
              print STDERR "INFO: However the archive '$file_path' contains another file/stream which is supported by $PASSWORD_RECOVERY_TOOL_NAME (this will be used)\n\n";
            }

            if ($codec_warning_shown == 0) # override old value only if no warning shown before
            {
              $codec_warning_shown = $tmp_codec_warning_shown;
            }

            next if ($attribute_error == 1);

            # special case: longer (previous) stream has no codec warnings, but shorter one has:
            # (therefore we still prefer the one that the cracker supports)

            next if (($found_stream_without_warning == 1) &&
                     ($tmp_codec_warning_shown      == 1));

            # now it's save to override the non-tmp variables (we have a hit):

            $type_of_data          = $tmp_type_of_data;
            $additional_attributes = $tmp_additional_attributes;

            $attributes = @$coders[$aes_coder_index]->{'attributes'};

            if ($tmp_codec_warning_shown == 0)
            {
              $found_stream_without_warning = 1;
            }

            #
            # set the "new" hash properties (for this specific/better stream with smaller first file):
            #

            ($salt_len, $salt_buf, $iv_len, $iv_buf, $number_cycles_power) = get_decoder_properties ($attributes);

            $crc = $digest->{'crc'};

            $crc_len  = $length_first_file;

            $data_len = $length_compressed;

            # $unpack_size = $length_first_file;
            $unpack_size = get_folder_aes_unpack_size ($unpack_info, $stream_index);

            $data_offset = $data_offset_tmp;

            # we assume that $type_of_data and $type_of_compression didn't change between the streams
            # (this should/could be checked too to avoid any strange problems)
          }
        }

        if ($SHOW_LIST_OF_ALL_STREAMS == 1)
        {
          print STDERR sprintf ("DEBUG: shortest file at the beginning of a stream consists of %d bytes (offset: %d bytes)\n", $crc_len, $data_offset);
        }

        if ($data_offset > 0)
        {
          my_seek ($fp, $position_after_header + $position_pack + $data_offset, 0);
        }
      }

      if ($SHORTEN_HASH_LENGTH_TO_CRC_LENGTH == 1)
      {
        my $aes_len = int ($SHORTEN_HASH_FIXED_HEADER + $crc_len + $SHORTEN_HASH_EXTRA_PERCENT / 100 * $crc_len);

        my $AES_BLOCK_SIZE = 16;

        $aes_len += $AES_BLOCK_SIZE - 1; # add these bytes to be sure to always include the last "block" too (round up and cast)

        $aes_len = int ($aes_len / $AES_BLOCK_SIZE) * $AES_BLOCK_SIZE;

        if ($aes_len < $data_len)
        {
          $data_len    = $aes_len;
          $unpack_size = $aes_len;
        }
      }
    }

    $data = my_read ($fp, $data_len); # NOTE: we shouldn't read a very huge data buffer directly into memory
                                      # improvement: read the data in chunks of several MBs and keep printing it
                                      # directly to stdout (by also not returning a string from this function)
                                      # that would help to achieve minimal RAM consumption (even for very large hashes)
  }

  return "" unless (length ($data) == $data_len);

  if ($data_len > ($PASSWORD_RECOVERY_TOOL_DATA_LIMIT / 2))
  {
    print STDERR "WARNING: the file '". $file_path . "' unfortunately can't be used with $PASSWORD_RECOVERY_TOOL_NAME since the data length\n";
    print STDERR "in this particular case is too long ($data_len of the maximum allowed " . ($PASSWORD_RECOVERY_TOOL_DATA_LIMIT / 2) . " bytes).\n";

    if ($PASSWORD_RECOVERY_TOOL_SUPPORT_PADDING_ATTACK == 1)
    {
      print STDERR "Furthermore, it could not be truncated. This should only happen in very rare cases.\n";
    }

    return "";
  }

  if ($unpack_size > $data_len)
  {
    print STDERR "WARNING: some file info seem to be conflicting. The length (metadata) of decrypted data seems to be larger than the actual encrypted (and compressed, if applicable) data length.\n";
    print STDERR "This could also be a potential problem with this hash extraction script (please report this issue if it is reproducible with known data and password).\n";

    $unpack_size = $data_len; # our MAX ()
  }

  $hash_buf = basename ($file_path) . ":" . $hash_buf if $PASSWORD_RECOVERY_TOOL_NAME eq "john";

  $hash_buf .= sprintf ("%s%u\$%u\$%u\$%s\$%u\$%s\$%u\$%u\$%u\$%s",
    $SEVEN_ZIP_HASH_SIGNATURE,
    $type_of_data,
    $number_cycles_power,
    $salt_len,
    unpack ("H*", $salt_buf),
    $iv_len,
    unpack ("H*", $iv_buf),
    $crc,
    $data_len,
    $unpack_size,
    unpack ("H*", $data) # could be very large. We could/should avoid loading/copying this data into memory
  );

  if (length ($hash_buf) > $PASSWORD_RECOVERY_TOOL_DATA_LIMIT)
  {
    print STDERR "WARNING: the file '". $file_path . "' unfortunately can't be used with $PASSWORD_RECOVERY_TOOL_NAME since the overall length of the hash line in this particular case is too long (" . length ($hash_buf) . " of the maximum allowed " . $PASSWORD_RECOVERY_TOOL_DATA_LIMIT . " bytes).\n";

    return "";
  }

  return $hash_buf if ($type_of_data == $SEVEN_ZIP_UNCOMPRESSED);
  return $hash_buf if ($type_of_data == $SEVEN_ZIP_TRUNCATED);

  $hash_buf .= sprintf ("\$%u\$%s",
    $crc_len,
    $additional_attributes
  );

  if (length ($hash_buf) > $PASSWORD_RECOVERY_TOOL_DATA_LIMIT)
  {
    print STDERR "WARNING: the file '". $file_path . "' unfortunately can't be used with $PASSWORD_RECOVERY_TOOL_NAME since the overall length of the hash line in this particular case is too long (" . length ($hash_buf) . " of the maximum allowed " . $PASSWORD_RECOVERY_TOOL_DATA_LIMIT . " bytes).\n";

    return "";
  }

  return $hash_buf;
}

sub read_seven_zip_signature_header
{
  my $fp = shift;

  my $signature;

  # ArchiveVersion

  my $major_version = my_read ($fp, 1);

  $major_version = ord ($major_version);

  my $minor_version = my_read ($fp, 1);

  $minor_version = ord ($minor_version);

  # StartHeaderCRC

  my_read ($fp, 4); # skip start header CRC

  # StartHeader

  my $next_header_offset = get_uint64 ($fp);
  my $next_header_size   = get_uint64 ($fp);

  my_read ($fp, 4); # next header CRC

  my $position_after_header = my_tell ($fp);

  $signature = {
    "major_version" => $major_version,
    "minor_version" => $minor_version,
    "next_header_offset" => $next_header_offset,
    "next_header_size" => $next_header_size,
    "position_after_header" => $position_after_header
  };

  return $signature;
}

sub skip_seven_zip_data
{
  my $fp = shift;

  # determine the length to skip

  my $len = my_read ($fp, 1);

  # do skip len bytes

  $len = ord ($len);

  my_read ($fp, $len);
}

sub wait_for_seven_zip_id
{
  my $fp = shift;
  my $id = shift;

  while (1)
  {
    my $new_id = read_id ($fp);

    if ($new_id eq $id)
    {
      return 1;
    }
    elsif ($new_id eq $SEVEN_ZIP_END)
    {
      return 0;
    }

    skip_seven_zip_data ($fp);
  }

  return 0;
}

sub read_seven_zip_digests
{
  my $fp = shift;

  my $number_items = shift;

  my @digests;

  # init

  for (my $i = 0; $i < $number_items; $i++)
  {
    my $digest = {
      "crc" => "",
      "defined" => 0
    };

    push (@digests, $digest)
  }

  # get number of items

  my @digests_defined = get_boolean_vector_check_all ($fp, $number_items);

  # for each number of item, get a digest

  for (my $i = 0; $i < $number_items; $i++)
  {
    my $crc = 0;

    for (my $i = 0; $i < 4; $i++)
    {
      my $val = my_read ($fp, 1);

      $val = ord ($val);

      $crc |= ($val << (8 * $i));
    }

    $digests[$i]->{'crc'} = $crc;
    $digests[$i]->{'defined'} = $digests_defined[$i];
  }

  return @digests;
}

sub read_seven_zip_pack_info
{
  my $fp = shift;

  my $pack_info;

  # PackPos

  my $pack_pos = read_number ($fp);

  # NumPackStreams

  my $number_pack_streams = read_number ($fp);

  # must be "size" id

  if (! wait_for_seven_zip_id ($fp, $SEVEN_ZIP_SIZE))
  {
    return undef;
  }

  my @pack_sizes = (0) x $number_pack_streams;

  for (my $i = 0; $i < $number_pack_streams; $i++)
  {
    $pack_sizes[$i] = read_number ($fp);
  }

  $pack_info = {
    "number_pack_streams" => $number_pack_streams,
    "pack_pos" => $pack_pos,
    "pack_sizes" => \@pack_sizes
  };

  # read remaining data

  while (1)
  {
    my $id = read_id ($fp);

    if ($id eq $SEVEN_ZIP_END)
    {
      return $pack_info;
    }
    elsif ($id eq $SEVEN_ZIP_CRC)
    {
      my $digests = read_seven_zip_digests ($fp, $number_pack_streams);

      # we do not need those digests, ignore them
      # (but we need to read them from the stream)

      next;
    }

    skip_seven_zip_data ($fp);
  }

  # something went wrong

  return undef;
}

sub read_seven_zip_folders
{
  my $fp = shift;

  my $folder;

  my @coders = ();
  my @bindpairs = ();
  my $index_main_stream = 0;
  my $sum_input_streams  = 0;
  my $sum_output_streams = 0;
  my $sum_packed_streams = 1;

  # NumCoders

  my $number_coders = read_number ($fp);

  # loop

  for (my $i = 0; $i < $number_coders; $i++)
  {
    my $main_byte = my_read ($fp, 1);

    $main_byte = ord ($main_byte);

    if ($main_byte & 0xC0)
    {
      return undef;
    }

    my $codec_id_size = $main_byte & 0xf;

    if ($codec_id_size > 8)
    {
      return undef;
    }

    # the codec id (very important info for us):
    # codec_id: 06F10701 -> AES-256 + SHA-256
    # codec_id: 030101   -> lzma  (we need to decompress - k_LZMA)
    # codec_id: 21       -> lzma2 (we need to decompress - k_LZMA2)

    my $codec_id = my_read ($fp, $codec_id_size);

    # NumInStreams

    my $number_input_streams = 1;

    # NumOutStreams

    my $number_output_streams = 1;

    if (($main_byte & 0x10) != 0)
    {
      $number_input_streams  = read_number ($fp);
      $number_output_streams = read_number ($fp);
    }

    $sum_input_streams  += $number_input_streams;
    $sum_output_streams += $number_output_streams;

    # attributes

    my $attributes;

    if (($main_byte & 0x020) != 0)
    {
      my $property_size = read_number ($fp);

      $attributes = my_read ($fp, $property_size);
    }

    $coders[$i] = {
      "codec_id" => $codec_id,
      "number_input_streams" => $number_input_streams,
      "number_output_streams" => $number_output_streams,
      "attributes" => $attributes
    };
  }

  if (($sum_input_streams != 1) || ($sum_output_streams != 1))
  {
    # InStreamUsed / OutStreamUsed

    my @input_stream_used  = (0) x $sum_input_streams;
    my @output_stream_used = (0) x $sum_output_streams;

    # BindPairs

    my $number_bindpairs = $sum_output_streams - 1;

    for (my $i = 0; $i < $number_bindpairs; $i++)
    {
      # input

      my $index_input = read_number ($fp);

      if ($input_stream_used[$index_input] == 1)
      {
        return undef; # the stream is used already, shouldn't happen at all
      }

      $input_stream_used[$index_input] = 1;

      # output

      my $index_output = read_number ($fp);

      if ($output_stream_used[$index_output] == 1)
      {
        return undef;
      }

      $output_stream_used[$index_output] = 1;

      my @new_bindpair = ($index_input, $index_output);

      push (@bindpairs, \@new_bindpair);
    }

    # PackedStreams

    $sum_packed_streams = $sum_input_streams - $number_bindpairs;

    if ($sum_packed_streams != 1)
    {
      for (my $i = 0; $i < $sum_packed_streams; $i++)
      {
        # we can ignore this

        read_number ($fp); # my $index = read_number ($fp);
      }
    }

    # determine the main stream

    $index_main_stream = -1;

    for (my $i = 0; $i < $sum_output_streams; $i++)
    {
      if ($output_stream_used[$i] == 0)
      {
        $index_main_stream = $i;

        last;
      }
    }

    if ($index_main_stream == -1)
    {
      return undef; # should not happen
    }
  }

  $folder = {
    "number_coders" => $number_coders,
    "coders" => \@coders,
    "bindpairs" => \@bindpairs,
    "index_main_stream"  => $index_main_stream,
    "sum_input_streams"  => $sum_input_streams,
    "sum_output_streams" => $sum_output_streams,
    "sum_packed_streams" => $sum_packed_streams,
  };

  return $folder;
}

sub read_seven_zip_unpack_info
{
  my $fp = shift;

  my $unpack_info;

  my $number_folders = 0;
  my @folders = ();
  my @datastream_indices = ();
  my @unpack_sizes;
  my @digests;
  my @main_unpack_size_index;
  my @coder_unpack_sizes;

  # check until we see the "folder" id

  if (! wait_for_seven_zip_id ($fp, $SEVEN_ZIP_FOLDER))
  {
    return undef;
  }

  # NumFolders

  $number_folders = read_number ($fp);

  # External

  my $external = my_read ($fp, 1);

  # loop

  my $sum_coders_output_streams = 0;
  my $sum_folders = 0;

  for (my $i = 0; $i < $number_folders; $i++)
  {
    if ($external eq $SEVEN_ZIP_NOT_EXTERNAL)
    {
      my $folder = read_seven_zip_folders ($fp);

      $folders[$i] = $folder;

      $main_unpack_size_index[$i] = $folder->{'index_main_stream'};
      $coder_unpack_sizes[$i] = $sum_coders_output_streams;

      $sum_coders_output_streams += $folder->{'sum_output_streams'};

      $sum_folders++;
    }
    elsif ($external eq $SEVEN_ZIP_EXTERNAL)
    {
      $datastream_indices[$i] = read_number ($fp);
    }
    else
    {
      return undef;
    }
  }

  if (!wait_for_seven_zip_id ($fp, $SEVEN_ZIP_UNPACK_SIZE))
  {
    return undef;
  }

  for (my $i = 0; $i < $sum_coders_output_streams; $i++)
  {
    $unpack_sizes[$i] = read_number ($fp);
  }

  # read remaining data

  while (1)
  {
    my $id = read_id ($fp);

    if ($id eq $SEVEN_ZIP_END)
    {
      $unpack_info = {
        "number_folders" => $number_folders,
        "folders" => \@folders,
        "datastream_indices" => \@datastream_indices,
        "digests" => \@digests,
        "unpack_sizes" => \@unpack_sizes,
        "main_unpack_size_index" => \@main_unpack_size_index,
        "coder_unpack_sizes" => \@coder_unpack_sizes
      };

      return $unpack_info;
    }
    elsif ($id eq $SEVEN_ZIP_CRC)
    {
      my @new_digests = read_seven_zip_digests ($fp, $sum_folders);

      for (my $i = 0; $i < $sum_folders; $i++)
      {
        $digests[$i]->{'defined'} = $new_digests[$i]->{'defined'};
        $digests[$i]->{'crc'} = $new_digests[$i]->{'crc'};
      }

      next;
    }

    skip_seven_zip_data ($fp);
  }

  # something went wrong

  return undef;
}

sub get_folder_unpack_size
{
  my $unpack_info  = shift;
  my $folder_index = shift;

  my $index = $unpack_info->{'coder_unpack_sizes'}[$folder_index] + $unpack_info->{'main_unpack_size_index'}[$folder_index];

  return $unpack_info->{'unpack_sizes'}[$index];
}

sub get_folder_aes_unpack_size
{
  my $unpack_info  = shift;
  my $folder_index = shift;

  my $index = $unpack_info->{'coder_unpack_sizes'}[$folder_index];

  return $unpack_info->{'unpack_sizes'}[$index];
}

sub has_valid_folder_crc
{
  my $digests = shift;
  my $index   = shift;

  if (! defined (@$digests[$index]))
  {
    return 0;
  }

  my $digest = @$digests[$index];

  if ($digest->{'defined'} != 1)
  {
    return 0;
  }

  if (length ($digest->{'crc'}) < 1)
  {
    return 0;
  }

  return 1;
}

sub read_seven_zip_substreams_info
{
  my $fp = shift;

  my $unpack_info = shift;

  my $number_folders = $unpack_info->{'number_folders'};
  my $folders = $unpack_info->{'folders'};

  my $folders_digests = $unpack_info->{'digests'};

  my $substreams_info;
  my @number_unpack_streams = (1) x $number_folders;
  my @unpack_sizes;
  my @digests;

  # get the numbers of unpack streams

  my $id;

  while (1)
  {
    $id = read_id ($fp);

    if ($id eq $SEVEN_ZIP_NUM_UNPACK_STREAM)
    {
      for (my $i = 0; $i < $number_folders; $i++)
      {
        $number_unpack_streams[$i] = read_number ($fp);
      }

      next;
    }
    elsif ($id eq $SEVEN_ZIP_CRC)
    {
      last;
    }
    elsif ($id eq $SEVEN_ZIP_SIZE)
    {
      last;
    }
    elsif ($id eq $SEVEN_ZIP_END)
    {
      last;
    }

    skip_seven_zip_data ($fp);
  }

  if ($id eq $SEVEN_ZIP_SIZE)
  {
    for (my $i = 0; $i < $number_folders; $i++)
    {
      my $number_substreams = $number_unpack_streams[$i];

      if ($number_substreams == 0)
      {
        next;
      }

      my $sum_unpack_sizes = 0;

      for (my $j = 1; $j < $number_substreams; $j++)
      {
        my $size = read_number ($fp);

        push (@unpack_sizes, $size);

        $sum_unpack_sizes += $size;
      }

      # add the folder unpack size itself

      my $folder_unpack_size = get_folder_unpack_size ($unpack_info, $i);

      if ($folder_unpack_size < $sum_unpack_sizes)
      {
        return undef;
      }

      my $size = $folder_unpack_size - $sum_unpack_sizes;

      push (@unpack_sizes, $size);
    }

    $id = read_id ($fp);
  }
  else
  {
    for (my $i = 0; $i < $number_folders; $i++)
    {
      my $number_substreams = $number_unpack_streams[$i];

      if ($number_substreams > 1)
      {
        return undef;
      }

      if ($number_substreams == 1)
      {
        push (@unpack_sizes, get_folder_unpack_size ($unpack_info, $i));
      }
    }
  }

  my $number_digests = 0;

  for (my $i = 0; $i < $number_folders; $i++)
  {
    my $number_substreams = $number_unpack_streams[$i];

    if (($number_substreams != 1) || (has_valid_folder_crc ($folders_digests, $i) == 0))
    {
      $number_digests += $number_substreams;
    }
  }

  while (1)
  {
    if ($id eq $SEVEN_ZIP_END)
    {
      last;
    }
    elsif ($id eq $SEVEN_ZIP_CRC)
    {
      my @is_digest_defined = get_boolean_vector_check_all ($fp, $number_digests);

      my $k  = 0;
      my $k2 = 0;

      for (my $i = 0; $i < $number_folders; $i++)
      {
        my $number_substreams = $number_unpack_streams[$i];

        if (($number_substreams == 1) && (has_valid_folder_crc ($folders_digests, $i)))
        {
          $digests[$k]->{'defined'} = 1;
          $digests[$k]->{'crc'} = @$folders_digests[$i]->{'crc'};

          $k++;
        }
        else
        {
          for (my $j = 0; $j < $number_substreams; $j++)
          {
            my $defined = $is_digest_defined[$k2];

            # increase k2

            $k2++;

            if ($defined == 1)
            {
              my $digest = 0;

              for (my $i = 0; $i < 4; $i++)
              {
                my $val = my_read ($fp, 1);

                $val = ord ($val);

                $digest |= ($val << (8 * $i));
              }

              $digests[$k]->{'defined'} = 1;
              $digests[$k]->{'crc'} = $digest;
            }
            else
            {
              $digests[$k]->{'defined'} = 0;
              $digests[$k]->{'crc'} = 0;
            }

            $k++;
          }
        }
      }
    }
    else
    {
      skip_seven_zip_data ($fp);
    }

    $id = read_id ($fp);
  }

  my $len_defined = scalar (@digests);
  my $len_unpack_sizes = scalar (@unpack_sizes);

  if ($len_defined != $len_unpack_sizes)
  {
    my $k = 0;

    for (my $i = 0; $i < $number_folders; $i++)
    {
      my $number_substreams = $number_unpack_streams[$i];

      if (($number_substreams == 1) && (has_valid_folder_crc ($folders_digests, $i)))
      {
        $digests[$k]->{'defined'} = 1;
        $digests[$k]->{'crc'} = @$folders_digests[$i]->{'crc'};

        $k++;
      }
      else
      {
        for (my $j = 0; $j < $number_substreams; $j++)
        {
          $digests[$k]->{'defined'} = 0;
          $digests[$k]->{'crc'} = 0;

          $k++;
        }
      }
    }
  }

  $substreams_info = {
    "unpack_stream_numbers" => \@number_unpack_streams,
    "unpack_sizes" => \@unpack_sizes,
    "number_digests" => $number_digests,
    "digests" => \@digests
  };

  return $substreams_info;
}

sub read_seven_zip_streams_info
{
  my $fp = shift;

  my $streams_info;

  my $pack_info;
  my $unpack_info;
  my $substreams_info;

  # get the type of streams info (id)

  my $id = read_id ($fp);

  if ($id eq $SEVEN_ZIP_PACK_INFO)
  {
    $pack_info = read_seven_zip_pack_info ($fp);

    return undef unless (defined ($pack_info));

    $id = read_id ($fp);
  }

  if ($id eq $SEVEN_ZIP_UNPACK_INFO)
  {
    $unpack_info = read_seven_zip_unpack_info ($fp);

    return undef unless (defined ($unpack_info));

    $id = read_id ($fp);
  }

  if ($id eq $SEVEN_ZIP_SUBSTREAMS_INFO)
  {
    $substreams_info = read_seven_zip_substreams_info ($fp, $unpack_info);

    return undef unless (defined ($substreams_info));

    $id = read_id ($fp);
  }
  else
  {
    my @number_unpack_streams = ();
    my @unpack_sizes = ();
    my $number_digests = 0;
    my $digests;

    if (defined ($unpack_info))
    {
      my $folders = $unpack_info->{'folders'};

      my $number_folders = $unpack_info->{'number_folders'};

      for (my $i = 0; $i < $number_folders; $i++)
      {
        $number_unpack_streams[$i] = 1;

        my $folder_unpack_size = get_folder_unpack_size ($unpack_info, $i);

        push (@unpack_sizes, $folder_unpack_size);
      }
    }

    $substreams_info = {
      "unpack_stream_numbers" => \@number_unpack_streams,
      "unpack_sizes" => \@unpack_sizes,
      "number_digests" => $number_digests,
      "digests" => $digests
    };
  }

  $streams_info = {
    "pack_info" => $pack_info,
    "unpack_info" => $unpack_info,
    "substreams_info" => $substreams_info
  };

  return $streams_info;
}

sub read_seven_zip_archive_properties
{
  my $fp = shift;

  # also the 7-Zip source code just skip data from the archive property entry

  while (1)
  {
    my $id = read_id ($fp);

    if ($id eq $SEVEN_ZIP_END)
    {
      return 1;
    }

    skip_seven_zip_data ($fp);
  }

  # something went wrong

  return 0;
}

sub get_uint64_defined_vector
{
  my $fp = shift;

  my $number_items = shift;

  my @values;

  # first check if the values are defined

  my @defines = get_boolean_vector_check_all ($fp, $number_items);

  my $external = my_read ($fp, 1);

  if ($external eq $SEVEN_ZIP_EXTERNAL)
  {
    # ignored for now
  }

  for (my $i = 0; $i < $number_items; $i++)
  {
    my $defined = $defines[$i];

    my $value = 0;

    if ($defined != 0)
    {
      $value = get_uint64 ($fp);
    }

    $values[$i] = $value;
  }

  return @values;
}

sub read_seven_zip_files_info
{
  my $fp = shift;

  my $streams_info = shift;

  my $files_info;

  my @files;

  # NumFiles

  my $number_files = read_number ($fp);

  # init file

  for (my $i = 0; $i < $number_files; $i++)
  {
    $files[$i]->{'name_utf16'} = "";
    $files[$i]->{'attribute_defined'} = 0;
    $files[$i]->{'attribute'} = 0;
    $files[$i]->{'is_empty_stream'} = 0;
    $files[$i]->{'start_position'} = 0;
    $files[$i]->{'creation_time'} = 0;
    $files[$i]->{'access_time'} = 0;
    $files[$i]->{'modification_time'} = 0;
    $files[$i]->{'size'} = 0;
    $files[$i]->{'has_stream'} = 0;
    $files[$i]->{'is_dir'} = 0;
    $files[$i]->{'crc_defined'} = 0;
    $files[$i]->{'crc'} = "";
  }

  my $number_empty_streams = 0;

  my @empty_streams = (0) x $number_files;
  my @empty_files   = (0) x $number_files;
  my @anti_files    = (0) x $number_files;

  # loop over all properties

  while (1)
  {
    my $property_type_val = read_number ($fp);

    my $property_type = num_to_id ($property_type_val);

    if ($property_type eq $SEVEN_ZIP_END)
    {
      last;
    }

    # Size

    my $size = read_number ($fp);

    # check and act according to the type of property found

    my $is_known_type = 1;

    if ($property_type_val > $SEVEN_ZIP_MAX_PROPERTY_TYPE)
    {
      # ignore (isKnownType false in 7-Zip source code)

      my_read ($fp, $size);
    }
    else
    {
      if ($property_type eq $SEVEN_ZIP_NAME)
      {
        my $external = my_read ($fp, 1);

        if ($external eq $SEVEN_ZIP_EXTERNAL)
        {
          # TODO: not implemented yet

          return undef;
        }

        my $files_size = scalar (@files);

        for (my $i = 0; $i < $files_size; $i++)
        {
          my $name = "";

          while (1)
          {
            my $name_part = my_read ($fp, 2);

            if ($name_part eq $SEVEN_ZIP_FILE_NAME_END)
            {
              last;
            }
            else
            {
              $name .= $name_part;
            }
          }

          $files[$i]->{'name_utf16'} = $name;
        }
      }
      elsif ($property_type eq $SEVEN_ZIP_WIN_ATTRIBUTE)
      {
        my $files_size = scalar (@files);

        my @booleans = get_boolean_vector_check_all ($fp, $number_files);

        my $external = my_read ($fp, 1);

        if ($external eq $SEVEN_ZIP_EXTERNAL)
        {
          # TODO: not implemented yet

          return undef;
        }

        for (my $i = 0; $i < $number_files; $i++)
        {
          my $defined = $booleans[$i];

          $files[$i]->{'attribute_defined'} = $defined;

          if ($defined)
          {
            my $attributes = get_uint32 ($fp);

            $files[$i]->{'attribute'} = $attributes;
          }
        }
      }
      elsif ($property_type eq $SEVEN_ZIP_EMPTY_STREAM)
      {
        @empty_streams = get_boolean_vector ($fp, $number_files);

        $number_empty_streams = 0;

        # loop over all boolean and set the files attribute + empty/anti stream vector

        my $number_booleans = scalar (@empty_streams);

        for (my $i = 0; $i < $number_booleans; $i++)
        {
          my $boolean = $empty_streams[$i];

          $files[$i]->{'is_empty_stream'} = $boolean;

          if ($boolean)
          {
            $number_empty_streams++;
          }
        }

        for (my $i = 0; $i < $number_empty_streams; $i++)
        {
          $empty_files[$i] = 0;
          $anti_files[$i]  = 0;
        }
      }
      elsif ($property_type eq $SEVEN_ZIP_EMPTY_FILE)
      {
        @empty_files = get_boolean_vector ($fp, $number_empty_streams);
      }
      elsif ($property_type eq $SEVEN_ZIP_ANTI_FILE)
      {
        @anti_files = get_boolean_vector ($fp, $number_empty_streams);
      }
      elsif ($property_type eq $SEVEN_ZIP_START_POS)
      {
        my @start_positions = get_uint64_defined_vector ($fp, $number_files);

        my $number_start_positions = scalar (@start_positions);

        for (my $i = 0; $i < $number_start_positions; $i++)
        {
          $files[$i]->{'start_position'} = $start_positions[$i];
        }
      }
      elsif ($property_type eq $SEVEN_ZIP_CREATION_TIME)
      {
        my @creation_times = get_uint64_defined_vector ($fp, $number_files);

        my $number_creation_times = scalar (@creation_times);

        for (my $i = 0; $i < $number_creation_times; $i++)
        {
          $files[$i]->{'creation_time'} = $creation_times[$i];
        }
      }
      elsif ($property_type eq $SEVEN_ZIP_ACCESS_TIME)
      {
        my @access_times = get_uint64_defined_vector ($fp, $number_files);

        my $number_access_times = scalar (@access_times);

        for (my $i = 0; $i < $number_access_times; $i++)
        {
          $files[$i]->{'access_time'} = $access_times[$i];
        }
      }
      elsif ($property_type eq $SEVEN_ZIP_MODIFICATION_TIME)
      {
        my @modification_times = get_uint64_defined_vector ($fp, $number_files);

        my $number_modification_times = scalar (@modification_times);

        for (my $i = 0; $i < $number_modification_times; $i++)
        {
          $files[$i]->{'modification_time'} = $modification_times[$i];
        }
      }
      elsif ($property_type eq $SEVEN_ZIP_DUMMY)
      {
        my $compare_bytes = "\x00" x $size;

        my $bytes = my_read ($fp, $size);

        if ($bytes ne $compare_bytes)
        {
          return undef;
        }
      }
      else
      {
        # ignore (isKnownType also in 7-Zip source code)

        my_read ($fp, $size);
      }
    }
  }

  # next id should be SEVEN_ZIP_END, but we (and 7-ZIP source code too) do not care

  my $id = read_id ($fp);

  # check anti files

  my $number_anti_items = 0;

  for (my $i = 0; $i < $number_empty_streams; $i++)
  {
    if ($anti_files[$i] != 0)
    {
      $number_anti_items++;
    }
  }

  # set digests depending on empty/anti files

  my $index_sizes = 0;
  my $index_empty_files = 0;

  my $unpack_info = $streams_info->{'unpack_info'};
  my $substreams_info = $streams_info->{'substreams_info'};

  for (my $i = 0; $i < $number_files; $i++)
  {
    my $is_anti = 0;
    my $has_stream = 1;

    if ($empty_streams[$i] == 1)
    {
      $has_stream = 0;
    }

    $files[$i]->{'has_stream'} = $has_stream;
    $files[$i]->{'crc'} = "";

    if ($has_stream == 1)
    {
      $is_anti = 0;

      $files[$i]->{'is_dir'} = 0;
      $files[$i]->{'size'} = $unpack_info->{'unpack_sizes'}[$index_sizes];

      $files[$i]->{'crc_defined'} = 0;
      $files[$i]->{'crc'} = "";

      my $is_crc_defined = has_valid_folder_crc ($unpack_info->{'digests'}, $index_sizes);

      if ($is_crc_defined == 1)
      {
        $files[$i]->{'crc_defined'} = 1;

        my $crc_item = $unpack_info->{'digests'}[$index_sizes];

        $files[$i]->{'crc'} = $crc_item->{'crc'};
      }
      else
      {
        # can we really do this too?

        $is_crc_defined = has_valid_folder_crc ($substreams_info->{'digests'}, $index_sizes);

        if ($is_crc_defined == 1)
        {
          $files[$i]->{'crc_defined'} = 1;

          my $crc_item = $substreams_info->{'digests'}[$index_sizes];

          $files[$i]->{'crc'} = $crc_item->{'crc'};
        }
      }

      $index_sizes++;
    }
    else
    {
      my $is_dir = 0;

      if ($empty_files[$index_empty_files] == 0)
      {
        $files[$i]->{'is_dir'} = 1;
      }
      else
      {
        $files[$i]->{'is_dir'} = 0;
      }

      $files[$i]->{'size'} = 0;

      $files[$i]->{'crc_defined'} = 0;
      $files[$i]->{'crc'} = "";

      $index_empty_files++;
    }
  }

  $files_info = {
    "number_files" => $number_files,
    "files" => \@files
  };

  return $files_info;
}

sub read_seven_zip_header
{
  my $fp = shift;

  my $header;

  my $additional_streams_info;
  my $streams_info;
  my $files_info;

  # get the type of header

  my $id = read_id ($fp);

  if ($id eq $SEVEN_ZIP_ARCHIVE_PROPERTIES)
  {
    # we just ignore the data here (but we need to read it from the stream!)

    if (! read_seven_zip_archive_properties ($fp))
    {
      return undef;
    }

    $id = read_id ($fp);
  }

  if ($id eq $SEVEN_ZIP_ADD_STREAMS_INFO)
  {
    $additional_streams_info = read_and_decode_seven_zip_packed_stream ($fp);

    return undef unless (defined ($additional_streams_info));

    # do we need to change the start position here ?

    $id = read_id ($fp);
  }

  if ($id eq $SEVEN_ZIP_MAIN_STREAMS_INFO)
  {
    $streams_info = read_seven_zip_streams_info ($fp);

    return undef unless (defined ($streams_info));

    $id = read_id ($fp);
  }

  if ($id eq $SEVEN_ZIP_FILES_INFO)
  {
    $files_info = read_seven_zip_files_info ($fp, $streams_info);

    return undef unless (defined ($files_info));
  }

  $header = {
    "additional_streams_info" => $additional_streams_info,
    "streams_info" => $streams_info,
    "files_info" => $files_info,
    "type" => "raw"
  };

  return $header;
}

sub read_and_decode_seven_zip_packed_stream
{
  my $fp = shift;

  my $packed_stream;

  $packed_stream = read_seven_zip_streams_info ($fp);

  # for each folder, get the decoder and decode the data

  return $packed_stream;
}

sub parse_seven_zip_header
{
  my $fp = shift;

  my $header;
  my $streams_info;

  # get the type of the header (id)

  my $id = read_id ($fp);

  # check if either encoded/packed or encrypted: to get the details we need to check the method

  if ($id ne $SEVEN_ZIP_HEADER)
  {
    if ($id ne $SEVEN_ZIP_ENCODED_HEADER)
    {
      # when we reach this code section we probably found an invalid 7z file (just ignore it!)
      # print STDERR "WARNING: only encoded headers are allowed if no raw header is present\n";

      return undef;
    }

    $streams_info = read_and_decode_seven_zip_packed_stream ($fp);

    return undef unless (defined ($streams_info));

    $header = {
      "additional_streams_info" => undef,
      "streams_info" => $streams_info,
      "files_info" => undef,
      "type" => "encoded"
    }

    # Note: now the 7-Zip code normally parses the header (which we got from the decode operation above)
    # but we do not really need to do this here. Skip
  }
  else
  {
    $header = read_seven_zip_header ($fp);
  }

  return $header;
}

sub read_seven_zip_next_header
{
  my $fp = shift;

  my $header_size   = shift;
  my $header_offset = shift;

  my $header;

  # get the header of size header_size at relative position header_offset

  my_seek ($fp, $header_offset, 1);

  # read the header

  $header = parse_seven_zip_header ($fp);

  return $header;
}

sub read_seven_zip_archive
{
  my $fp = shift;

  my $archive;

  # SignatureHeader

  my $signature = read_seven_zip_signature_header ($fp);

  return undef unless (defined ($signature));

  # parse the header

  my $parsed_header = read_seven_zip_next_header ($fp, $signature->{'next_header_size'}, $signature->{'next_header_offset'});

  return undef unless (defined ($parsed_header));

  $archive = {
    "signature_header" => $signature,
    "parsed_header" => $parsed_header
  };

  return $archive;
}

sub seven_zip_get_hash
{
  my $file_path = shift;

  my $hash_buf = "";

  # open file for reading

  my $seven_zip_file;

  if (! open ($seven_zip_file, "<$file_path"))
  {
    print STDERR "WARNING: could not open the file '$file_path' for reading\n";

    return $hash_buf;
  }

  binmode ($seven_zip_file);

  # check if valid and supported 7z file

  if (! is_supported_seven_zip_file ($seven_zip_file))
  {
    return sfx_get_hash ($seven_zip_file, $file_path);
  }

  my $archive = read_seven_zip_archive ($seven_zip_file);

  $hash_buf = extract_hash_from_archive ($seven_zip_file, $archive, $file_path);

  # cleanup

  close ($seven_zip_file);

  return $hash_buf;
}

#
# SFX related helper functions
#

# The strategy here is as follows:
# 1. only use sfx-checks whenever the 7z header is not at start (i.e. if parsing of a "regular" 7z failed)
# 2. try to read PE
# 3. try to search for $SEVEN_ZIP_MAGIC within the 512 bytes bounderies
# 4. try to do a full scan ($SEVEN_ZIP_MAGIC_LEN bytes at a time)

# sfx_7z_pe_search () searches for the 7z signature by seeking to the correct offset in the PE file
# (e.g. after the PE stub aka the executable part)

sub sfx_7z_pe_search
{
  my $fp = shift;

  my $found = 0;


  # 1. DOS header (e_lfanew)
  # 2. Portable executable (PE) headers (NumberOfSections)
  # 3. Section headers (PointerToRawData + SizeOfRawData)

  # we assume that the file is a common/standard PE executable, we will do some checks:

  # DOS header

  # we should have a MS-DOS MZ executable

  my $bytes = my_read ($fp, 2);

  return 0 if (length ($bytes) != 2);
  return 0 if ($bytes ne "MZ"); # 0x5a4d
  return 0 if (length (my_read ($fp, 58)) != 58);

  $bytes = my_read ($fp, 4);

  return 0 if (length ($bytes) != 4);

  my $e_lfanew = unpack ("L", $bytes);

  my_seek ($fp, $e_lfanew, 0);

  # PE header

  $bytes = my_read ($fp, 4); # PE0000 signature after DOS part

  return 0 if (length ($bytes) != 4);
  return 0 if ($bytes ne "PE\x00\x00");
  return 0 if (length (my_read ($fp, 2)) != 2); # skip FileHeader.Machine

  $bytes = my_read ($fp, 2);

  return 0 if (length ($bytes) != 2);

  my $num_sections = unpack ("S", $bytes);

  return 0 if ($num_sections < 1);

  return 0 if (length (my_read ($fp,  16)) !=  16); # skip rest of FileHeader
  return 0 if (length (my_read ($fp, 224)) != 224); # skip OptionalHeader

  my $section_farthest = 0;
  my $pos_after_farthest_section = 0;

  for (my $i = 0; $i < $num_sections; $i++)
  {
    # we loop through all the section headers

    #my $name = my_read ($fp, 8); return 0 if (length (my_read ($fp, 8)) != 8);
    return 0 if (length (my_read ($fp, 16)) != 16); # skip Name, Misc, VirtualAddress, SizeOfRawData

    # SizeOfRawData

    $bytes = my_read ($fp, 4);

    return 0 if (length ($bytes) != 4);

    my $size_of_raw_data = unpack ("L", $bytes);

    # PointerToRawData

    $bytes = my_read ($fp, 4);

    return 0 if (length ($bytes) != 4);

    my $pointer_to_raw_data = unpack ("L", $bytes);

    # the sections are not quaranteed to be ordered (=> compare all of them!)

    if ($pointer_to_raw_data > $section_farthest)
    {
      $section_farthest = $pointer_to_raw_data;

      $pos_after_farthest_section = $pointer_to_raw_data + $size_of_raw_data;
    }


    # loop to next SectionTable entry

    return 0 if (length (my_read ($fp, 16)) != 16); # skip rest of SectionHeader
  }

  # check if 7z signature found (after stub)

  my_seek ($fp, $pos_after_farthest_section, 0);

  $bytes = my_read ($fp, $SEVEN_ZIP_MAGIC_LEN);

  return 0 if (length ($bytes) != $SEVEN_ZIP_MAGIC_LEN);

  if ($bytes eq $SEVEN_ZIP_MAGIC)
  {
    $found = 1;
  }

  return $found;
}

# sfx_7z_512_search () searches for the 7z signature by only looking at every 512 byte boundery

sub sfx_7z_512_search
{
  my $fp = shift;

  my $found = 0;


  my $seek_skip = 512 - $SEVEN_ZIP_MAGIC_LEN;

  my $bytes = my_read ($fp, $SEVEN_ZIP_MAGIC_LEN);

  my $len_bytes = length ($bytes);

  while ($len_bytes == $SEVEN_ZIP_MAGIC_LEN)
  {
    if ($bytes eq $SEVEN_ZIP_MAGIC)
    {
      $found = 1;

      last;
    }

    my_seek ($fp, $seek_skip, 1);

    $bytes = my_read ($fp, $SEVEN_ZIP_MAGIC_LEN);

    $len_bytes = length ($bytes);
  }

  return $found;
}

# sfx_7z_full_search () searches for the 7z signature by looking at every byte in the file
# (this type of search should only be performed if no other variant worked)

sub sfx_7z_full_search
{
  my $fp = shift;

  my $found = 0;

  my $index_into_magic = 0;
  my $prev_index_into_magic = 0;

  my $len_bytes = $SEVEN_ZIP_MAGIC_LEN;

  while ($len_bytes == $SEVEN_ZIP_MAGIC_LEN)
  {
    my $bytes = my_read ($fp, $SEVEN_ZIP_MAGIC_LEN);

    last if (length ($bytes) == 0);

    $prev_index_into_magic = $index_into_magic;

    if ($bytes eq $SEVEN_ZIP_MAGIC)
    {
      $found = 1;

      last;
    }

    for (my $i = 0; $i < length ($bytes); $i++)
    {
      my $c = substr ($bytes, $i, 1);

      if ($c ne substr ($SEVEN_ZIP_MAGIC, $index_into_magic, 1))
      {
        $index_into_magic = 0; # reset
      }
      else
      {
        $index_into_magic++;

        if ($index_into_magic == $SEVEN_ZIP_MAGIC_LEN)
        {
          $found = 1;

          last;
        }
      }
    }

    last if ($found == 1);

    $len_bytes = length ($bytes);
  }

  return ($found, $prev_index_into_magic);
}

sub sfx_get_hash
{
  my $fp = shift;
  my $file_path = shift;

  my $hash_buf = "";


  my %db_positions_analysed = (); # holds a list of offsets that we already tried to parse

  # we make the assumption that there is max one .7z file within the .sfx!

  # Variant 1 (PE file structure parsing)

  my_seek ($fp, 0, 0);

  if (sfx_7z_pe_search ($fp))
  {
    my $cur_pos = my_tell ($fp);

    $db_positions_analysed{$cur_pos} = 1; # mark it as analyzed

    my $archive = read_seven_zip_archive ($fp);

    $hash_buf = extract_hash_from_archive ($fp, $archive, $file_path);

    if (defined ($hash_buf))
    {
      if (length ($hash_buf) > 0)
      {
        return $hash_buf;
      }
    }
  }

  # Variant 2 (search only at the 512 bytes bounderies)

  my_seek ($fp, 512, 0);

  while (sfx_7z_512_search ($fp) != 0)
  {
    my $cur_pos = my_tell ($fp);

    if (! exists ($db_positions_analysed{$cur_pos}))
    {
      $db_positions_analysed{$cur_pos} = 1; # mark it as analyzed

      my $archive = read_seven_zip_archive ($fp);

      $hash_buf = extract_hash_from_archive ($fp, $archive, $file_path);

      if (defined ($hash_buf))
      {
        if (length ($hash_buf) > 0)
        {
          return $hash_buf;
        }
      }
    }

    last if (my_seek ($fp, $cur_pos + 512 - $SEVEN_ZIP_MAGIC_LEN, 0) != 1);
  }

  # Variant 3 (full search - worst case - shouldn't happen at all with a standard .sfx)

  my_seek ($fp, 0, 2);

  my $file_size = my_tell ($fp);

  if ($file_size > 8 * 1024 * 1024) # let's say that 8 MiB is already a huge file
  {
    print STDERR "WARNING: searching for the 7z signature in a $file_size bytes long file ('";
    print STDERR $file_path . "') might take some time\n";
  }

  my_seek ($fp, 1, 0); # we do no that the signature is not at position 0, so we start at 1

  my ($full_search_found, $full_search_index) = sfx_7z_full_search ($fp);

  while ($full_search_found != 0)
  {
    my $cur_pos = my_tell ($fp);

    $cur_pos -= $full_search_index;

    my_seek ($fp, $cur_pos, 0); # we might not be there yet (depends if $full_search_index != 0)

    if (! exists ($db_positions_analysed{$cur_pos}))
    {
      # we can skip the database updates because it's our last try to find the 7z file
      # $db_positions_analysed{$cur_pos} = 1;

      my $archive = read_seven_zip_archive ($fp);

      $hash_buf = extract_hash_from_archive ($fp, $archive, $file_path);

      if (defined ($hash_buf))
      {
        if (length ($hash_buf) > 0)
        {
          return $hash_buf;
        }
      }
    }

    my_seek ($fp, $cur_pos, 0); # seek back to position JUST AFTER the previously found signature

    ($full_search_found, $full_search_index) = sfx_7z_full_search ($fp);
  }

  # in theory if we reach this code section we already know that parsing the file failed (but let's confirm it)

  my $sfx_successfully_parsed = 0;

  if (defined ($hash_buf))
  {
    if (length ($hash_buf) > 0)
    {
      $sfx_successfully_parsed = 1;
    }
  }

  if ($sfx_successfully_parsed == 0)
  {
    print STDERR "WARNING: the file '$file_path' is neither a supported 7-Zip file nor a supported SFX file\n";
  }

  # cleanup

  close ($fp);

  return $hash_buf;
}

sub globbing_on_windows
{
  my @file_list = @_;

  my $os = $^O;

  if (($os eq "MSWin32") || ($os eq "Win32"))
  {
    my $windows_globbing_module = "File::Glob";
    my $windows_globbing = "bsd_glob";

    if (eval "require $windows_globbing_module")
    {
      no strict 'refs';

      $windows_globbing_module->import ($windows_globbing);

      my @new_file_list = ();

      foreach my $item (@file_list)
      {
        push (@new_file_list, $windows_globbing-> ($item));
      }

      @file_list = @new_file_list;
    }
  }

  return @file_list;
}

sub get_splitted_archive_raw_name
{
  my $full_name = shift;

  my $name_index = rindex ($full_name, ".");

  my $name = substr ($full_name, 0, $name_index);

  return $name;
}

sub get_ordered_splitted_file_list
{
  my @files = @_;

  return () unless (scalar (@files) > 0); # never the case (already checked)

  my $failed = 0;
  my $num_probably_splitted_files = 0;

  my $file_prefix = "";
  my $extension_length = 0;

  foreach my $file_name (@files)
  {
    my $index_extension = rindex ($file_name, ".");

    if ($index_extension == -1)
    {
      $failed = 1;
      last;
    }

    my $prefix    = substr ($file_name, 0, $index_extension);
    my $extension = substr ($file_name, $index_extension + 1);

    if (length ($prefix) == 0)
    {
      $failed = 1;
      last;
    }

    # detect change in file prefix (the actual "name")

    if (length ($file_prefix) == 0) #init
    {
      $file_prefix = $prefix;
    }

    if ($prefix ne $file_prefix)
    {
      $failed = 1;
      last;
    }

    # check extensions (should be numbers only)

    if ($extension !~ /^[0-9]*$/)
    {
      $failed = 1;
      last;
    }

    if ($extension_length == 0) # init
    {
      $extension_length = length ($extension);
    }

    if (length ($extension) != $extension_length)
    {
      $failed = 1;
      last;
    }

    $num_probably_splitted_files++;
  }

  return () unless (length ($file_prefix) > 0);
  return () unless ($extension_length > 0);

  if ($failed == 1)
  {
    if ($num_probably_splitted_files > 1)
    {
      print STDERR "WARNING: it seems that some files could be part of a splitted 7z archive named '$file_prefix'\n";
      print STDERR "ATTENTION: make sure to only specify the files belonging to the splitted archive (do not combine them with other archives)\n";
    }

    return ();
  }

  # sort the list and check if there is no missing file
  # (at this point in time we can't verify if the last file is really the last one)

  my @sorted_file_list = sort (@files);

  my $max = scalar (@sorted_file_list);

  return () if ($max != scalar (@files));

  for (my $count = 0; $count < $max; $count++)
  {
    my $current_extension = sprintf ("%0${extension_length}i", $count + 1); # the splits start with .001, .002, ...

    return () if ($sorted_file_list[$count] ne "$file_prefix.$current_extension");
  }

  return @sorted_file_list;
}

sub get_file_sizes_list
{
  my @files = @_;

  my %files_with_sizes = ();

  my $accumulated_size = 0;

  for (my $count = 0; $count < scalar (@files); $count++)
  {
    my $file = $files[$count];

    my @file_stat = stat ($file);

    if (scalar (@file_stat) < 1)
    {
      print STDERR "ERROR: could not get the file size of the file '$file'\n";

      exit (1);
    }

    $files_with_sizes{0}{'fh'} = undef; # the file handle
    $files_with_sizes{0}{'num'} = 0;

    $files_with_sizes{$count + 1}{'name'}  = $file;
    $files_with_sizes{$count + 1}{'size'}  = $file_stat[7];
    $files_with_sizes{$count + 1}{'start'} = $accumulated_size;

    $accumulated_size += $file_stat[7];
  }

  return %files_with_sizes;
}

sub splitted_seven_zip_open
{
  my @files = @_;

  my @sorted_file_list = get_ordered_splitted_file_list (@files);

  return 0 if (scalar (@sorted_file_list) < 1);

  my %file_list_with_sizes = get_file_sizes_list (@sorted_file_list);

  # start to parse the file list

  $memory_buffer_read_offset = 0; # just to be safe

  my $first_splitted_file = $file_list_with_sizes{1}{'name'};

  my $hash_buf = "";

  # open file for reading

  my $seven_zip_file;

  if (! open ($seven_zip_file, "<$first_splitted_file"))
  {
    print STDERR "ERROR: could not open the the splitted archive file '$first_splitted_file' for reading\n";

    exit (1);
  }

  binmode ($seven_zip_file);

  $file_list_with_sizes{0}{'fh'}  = $seven_zip_file;
  $file_list_with_sizes{0}{'num'} = 1; # meaning is: "first file"

  # check if valid and supported 7z file

  if (! is_supported_seven_zip_file (\%file_list_with_sizes))
  {
    print STDERR "ERROR: the splitted archive file '$first_splitted_file' is not a valid 7z file\n";

    exit (1);
  }

  my $archive = read_seven_zip_archive (\%file_list_with_sizes);

  $hash_buf = extract_hash_from_archive (\%file_list_with_sizes, $archive, $first_splitted_file);

  # cleanup

  close ($seven_zip_file);

  if (defined ($hash_buf))
  {
    if (length ($hash_buf) > 0)
    {
      print $hash_buf . "\n";
    }
  }

  return 1;
}

#
# Start
#

my $display_sensitive_warning = $DISPLAY_SENSITIVE_DATA_WARNING;

my @file_parameters = ();

for (my $i = 0; $i < scalar (@ARGV); $i++)
{
  if ($ARGV[$i] eq "--skip-sensitive-data-warning")
  {
    $display_sensitive_warning = 0;
  }
  else
  {
    push (@file_parameters, $ARGV[$i]);
  }
}

if (scalar (@file_parameters) lt 1)
{
  usage ($0);

  exit (1);
}

my $first_file = 1;

my @file_list = globbing_on_windows (@file_parameters);

# try to handle this special case: splitted .7z files (.7z.001, .7z.002, .7z.003, ...)
# ATTENTION: there is one restriction here: splitted archives shouldn't be combined with other
# splitted or non-splitted archives

my $was_splitted = splitted_seven_zip_open (@file_list);

if ($was_splitted == 1)
{
  exit (0);
}

# "non-splitted" file list:

foreach my $file_name (@file_list)
{
  if (! -e $file_name)
  {
    print STDERR "WARNING: could not open file '$file_name'\n";

    next;
  }

  # reset the offset for the in-memory buffer before every new file:

  $memory_buffer_read_offset = 0;

  my $hash_buf = seven_zip_get_hash ($file_name);

  next unless (defined ($hash_buf));
  next unless (length ($hash_buf) > 0);

  if ($display_sensitive_warning == 1)
  {
    if ($first_file == 1)
    {
      print STDERR "ATTENTION: the hashes might contain sensitive encrypted data. Be careful when sharing or posting these hashes\n";

      $first_file = 0;
    }
  }

  print $hash_buf . "\n";
}

exit (0);