#!/bin/bash
# Cross-backend round-trip test for PQC algorithms.
# Verifies that keyrings generated by the Botan backend can be used by the
# OpenSSL backend, and vice versa, covering ML-KEM, ML-DSA, and SLH-DSA.
#
# Prerequisites
# -------------
# Two build directories must exist at the repository root before running
# this script.  Build them with cmake from the repo root, e.g.:
#
#   Botan backend (build/):
#     cmake -B build -DCRYPTO_BACKEND=botan3 \
#           -DENABLE_CRYPTO_REFRESH=ON -DENABLE_PQC=ON
#     cmake --build build --target rnp rnpkeys
#
#   OpenSSL 3.5+ backend (build-ossl/):
#     cmake -B build-ossl -DCRYPTO_BACKEND=OpenSSL \
#           -DOPENSSL_ROOT_DIR=<path-to-openssl-3.5> \
#           -DENABLE_CRYPTO_REFRESH=ON -DENABLE_PQC=ON
#     cmake --build build-ossl --target rnp rnpkeys
#
# Usage (from the repository root):
#   bash src/tests/pqc-crossbackend-test.sh

set -euo pipefail

REPO_ROOT=$(cd "$(dirname "$0")"/../.. && pwd)
BOTAN_RNP="$REPO_ROOT/build/src/rnp/rnp"
BOTAN_RNPK="$REPO_ROOT/build/src/rnpkeys/rnpkeys"
OSSL_RNP="$REPO_ROOT/build-ossl/src/rnp/rnp"
OSSL_RNPK="$REPO_ROOT/build-ossl/src/rnpkeys/rnpkeys"
PASSWORD="pqc-roundtrip-pw"

WORKDIR=$(mktemp -d)
trap 'rm -rf "$WORKDIR"' EXIT

PLAINTEXT="$WORKDIR/plaintext.txt"
echo "Cross-backend PQC round-trip test payload." > "$PLAINTEXT"

PASS=0
FAIL=0

# Generate a PQC key with one backend, sign+encrypt with that same backend,
# then decrypt+verify with the other backend using the same keyring files.
roundtrip() {
    local desc="$1"        # human-readable description
    local gen_rnpk="$2"   # rnpkeys binary used for key generation
    local gen_rnp="$3"    # rnp binary used for sign+encrypt
    local use_rnp="$4"    # rnp binary used for decrypt+verify
    local algo="$5"        # numeric algorithm choice for --generate-key --expert

    local uid="rt-${algo}@crossbackend"
    local dir="$WORKDIR/dir-${algo}-${desc// /-}"
    mkdir "$dir"

    # Key generation
    if ! printf '%s\n' "$algo" | \
            "$gen_rnpk" --homedir "$dir" --password "$PASSWORD" \
                        --notty --userid "$uid" --generate-key --expert \
                        2>/dev/null; then
        echo "FAIL [$desc algo=$algo] key generation failed"
        FAIL=$((FAIL+1))
        return
    fi

    local encrypted="$WORKDIR/enc-${algo}-${desc// /-}.pgp"
    local decrypted="$WORKDIR/dec-${algo}-${desc// /-}.txt"

    # Sign + encrypt with the generating backend
    if ! "$gen_rnp" --homedir "$dir" --sign --encrypt \
            -r "$uid" -u "$uid" \
            --pass-fd 3 "$PLAINTEXT" --output "$encrypted" \
            3< <(printf '%s' "$PASSWORD") 2>/dev/null; then
        echo "FAIL [$desc algo=$algo] sign+encrypt failed"
        FAIL=$((FAIL+1))
        return
    fi

    # Decrypt + verify with the other backend using the same keyring
    if ! "$use_rnp" --homedir "$dir" \
            --pass-fd 3 --decrypt "$encrypted" --output "$decrypted" \
            3< <(printf '%s' "$PASSWORD") 2>/dev/null; then
        echo "FAIL [$desc algo=$algo] decrypt+verify failed"
        FAIL=$((FAIL+1))
        return
    fi

    if ! diff -q "$PLAINTEXT" "$decrypted" > /dev/null 2>&1; then
        echo "FAIL [$desc algo=$algo] decrypted content differs from plaintext"
        FAIL=$((FAIL+1))
        return
    fi

    echo "PASS [$desc algo=$algo]"
    PASS=$((PASS+1))
}

# Algorithm numbers (from rnpkeys --generate-key --expert menu):
#  25: (ML-DSA-65 + Ed25519)   + (ML-KEM-768 + X25519)        -- Ed curves
#  26: (ML-DSA-87 + Ed448)     + (ML-KEM-1024 + X448)         -- Ed curves
#  27: (ML-DSA-65 + ECDSA-P384)+ (ML-KEM-768 + ECDH-P384)     -- NIST curves
#  28: (ML-DSA-87 + ECDSA-P521)+ (ML-KEM-1024 + ECDH-P521)    -- NIST curves
#  31: SLH-DSA-SHAKE-128f      + (ML-KEM-768 + X25519)        -- SLH-DSA
#  32: SLH-DSA-SHAKE-128s      + (ML-KEM-768 + X25519)        -- SLH-DSA
#  33: SLH-DSA-SHAKE-256s      + (ML-KEM-1024 + ECDH-P521)    -- SLH-DSA

echo "=== Botan generates, OpenSSL decrypts+verifies ==="
for algo in 25 26 27 28 31 32 33; do
    roundtrip "botan->ossl" "$BOTAN_RNPK" "$BOTAN_RNP" "$OSSL_RNP" "$algo"
done

echo ""
echo "=== OpenSSL generates, Botan decrypts+verifies ==="
for algo in 25 26 27 28 31 32 33; do
    roundtrip "ossl->botan" "$OSSL_RNPK" "$OSSL_RNP" "$BOTAN_RNP" "$algo"
done

echo ""
echo "Results: $PASS passed, $FAIL failed."
[ "$FAIL" -eq 0 ]