testing.md

Testing & Fuzzing

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Unit Tests

Test vectors are taken from NIST SP 800-38A for ECB, CBC, CFB, OFB, and CTR modes across all key sizes. generateKey() is validated against five PBKDF2-HMAC-SHA256 vectors cross-checked with Python's hashlib.pbkdf2_hmac.

cmake -B build -DQTAES_ENABLE_TESTS=ON -DCMAKE_PREFIX_PATH=/path/to/Qt
cmake --build build
ctest --test-dir build -V

OpenSSL interop cross-check

A separate test binary (AESCrossCheck) verifies byte-for-byte compatibility between Qt-AES and OpenSSL's EVP API in both directions (Qt→OpenSSL and OpenSSL→Qt) for all 5 modes × 3 key sizes, using NIST SP 800-38A plaintext/keys/IVs, plus corner cases for empty input and sub-block partial plaintext.

Requires libssl-dev (or equivalent) on the build host.

cmake -B build \
  -DQTAES_ENABLE_TESTS=ON \
  -DQTAES_ENABLE_OPENSSL_CROSS_CHECK=ON \
  -DCMAKE_PREFIX_PATH=/path/to/Qt
cmake --build build
ctest --test-dir build -V

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Fuzzing

A libFuzzer fuzz target lives in fuzz/fuzz_encrypt.cpp. It exercises all five cipher modes, all three key sizes, and all three padding schemes against randomly mutated inputs, and checks two properties on every input:

1. Crash freedom — neither encode() nor decode() ever crashes or triggers memory errors (AddressSanitizer is always active with -fsanitize=fuzzer).
2. Round-trip correctness — for PKCS7 padding, removePadding(decode(encode(pt))) == pt; for CTR mode, decode(encode(pt)) == pt directly.

Building and running

cmake -B build-fuzz \
  -DQTAES_ENABLE_FUZZING=ON \
  -DCMAKE_CXX_COMPILER=clang++ \
  -DCMAKE_PREFIX_PATH=/path/to/Qt

cmake --build build-fuzz --target fuzz_encrypt

# Run for 60 seconds, seeding from the provided corpus:
./build-fuzz/fuzz_encrypt fuzz/corpus/ -max_total_time=60

The fuzz/corpus/ directory contains seed inputs that cover all mode/level/padding combinations, giving the fuzzer a head start.