syntax = "proto3";

package io.intoto;

import "google/protobuf/struct.proto";

// An authenticated message of arbitrary type.
message Envelope {
  // Message to be signed. (In JSON, this is encoded as base64.)
  // REQUIRED.
  bytes payload = 1;

  // String unambiguously identifying how to interpret payload.
  // REQUIRED.
  string payloadType = 2;

  // Signature over:
  //     PAE(type, payload)
  // Where PAE is defined as:
  // PAE(type, payload) = "DSSEv1" + SP + LEN(type) + SP + type + SP + LEN(payload) + SP + payload
  // +               = concatenation
  // SP              = ASCII space [0x20]
  // "DSSEv1"        = ASCII [0x44, 0x53, 0x53, 0x45, 0x76, 0x31]
  // LEN(s)          = ASCII decimal encoding of the byte length of s, with no leading zeros
  // REQUIRED (length >= 1).
  repeated Signature signatures = 3;
}

message Signature {
  // Signature itself. (In JSON, this is encoded as base64.)
  // REQUIRED.
  bytes sig = 1;

  // *Unauthenticated* hint identifying which public key was used.
  // OPTIONAL.
  string keyid = 2;

  // *Unauthenticated* field that can record additional information pertaining
  // to the signature.
  // OPTIONAL.
  Extension extension = 3;
}

message Extension {
  // Unambiguously identifies how to interpret extension fields.
  // REQUIRED.
  string kind = 1;

  // Extension fields.
  // REQUIRED.
  google.protobuf.Struct ext = 2;
}