Validation and Interoperability

Validation & Interoperability

pqcrypto's correctness rests on two complementary kinds of evidence: Known-Answer Tests (KATs) prove it reproduces NIST's reference byte outputs, and OpenSSL interoperability proves a real independent implementation accepts its keys and ciphertexts and derives the same shared secret.

Known-Answer Tests (KATs)

Checked-in NIST vectors are reproduced byte-for-byte in the repository's test suite.

• ML-KEM: 1000 vectors per parameter set — 3000 total (512/768/1024).
• ML-DSA: byte-exact across the full matrix — 3 parameter sets × {det, hedged} × {raw, pure, hashed} — totalling 300 key generations and 1800 signatures that all verify.

Canonical details, file hashes, and gate commands: MLKEM_TESTING.md.

OpenSSL interoperability (ML-KEM)

The interop harness runs a suite (tests A–G) for all three ML-KEM parameter sets against OpenSSL's native ML-KEM (via libcrypto).

Test	What it proves
A / B	Each implementation is internally self-consistent.
C	OpenSSL decapsulates a pqcrypto ciphertext (×fuzz).
D	pqcrypto decapsulates an OpenSSL ciphertext (×fuzz).
E	Same 64-byte seed ⇒ byte-identical public keys.
F	Public-key wire round-trip is byte-identical.
G	Implicit-rejection secret agrees on an invalid ciphertext.

Only public keys, ciphertexts, and 64-byte seeds cross the boundary — never expanded private keys — mirroring how ML-KEM is actually deployed. Verified against OpenSSL 3.5.x and, in CI, 4.0.0.

Canonical matrix, versions, and reproduction steps: OPENSSL_INTEROP.md.

Why interop matters

KATs prove conformance to the standard's reference outputs. Interop proves the complementary real-world property: a key or ciphertext produced by one conformant implementation is accepted by another, and both derive the same shared secret. That is the property that decides whether a Dart client can talk to an OpenSSL-based server. It unlocks hybrid TLS components, Dart ↔ C/Python/ Node/Go exchange, and dual-stack migration — see the Cookbook interop ideas.

Run it yourself

dart test                                  # full unit + KAT suite (VM)
dart test -p chrome                        # dart2js web gate
dart test -p chrome --compiler dart2wasm   # dart2wasm web gate

The OpenSSL interop harness lives in tool/openssl_interop/ and needs OpenSSL ≥ 3.5. See OPENSSL_INTEROP.md for setup.

Caveat

This is functional conformance and wire compatibility — not a constant-time, side-channel, or CMVP/FIPS 140 claim. See Security Posture and FIPS Compliance.