> For the complete documentation index, see [llms.txt](https://polarischain-1.gitbook.io/polarischain/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://polarischain-1.gitbook.io/polarischain/4.-cryptographic-foundations-and-compliance-framework/4.4-cryptographic-audit-status-and-security-hardening.md).

# 4.4 - Cryptographic Audit Status & Security Hardening

A comprehensive quantum resistance audit was completed in **March 2026**, with subsequent hardening waves finalized through **April 2026**:

* ✅ **Classical asymmetric cryptography purged** — vestigial Ed25519 dependencies removed
* ✅ **Hash functions standardized** — SHA-256 replaced with BLAKE2b-256 across all production code
* ✅ **Dead crypto dependencies eliminated** — ChaCha20Poly1305 and unused ciphers stripped
* ✅ **P2P message authentication shipped** — all inter-validator messages signed with Dilithium2 via signed envelopes (protocol v7)
* ✅ **Post-quantum transport encryption enabled by default** — every P2P connection runs X25519 + ML-KEM-768 + Dilithium2 1-RTT PQXDH handshake; cannot be silently disabled in release builds
* ✅ **Encryption-at-rest hardened** — consensus, application, and hot-state stores support AES-256-GCM with operator passphrases derived via Argon2id, using per-store salt sidecars
* ✅ **Flexible key custody modes** — validator keys load from plaintext (dev), encrypted file (env/OS keyring), or environment variable (KMS flows); plaintext-in-production triggers release-build warnings
* ✅ **CSPRNG audit complete** — all security-critical randomness (keygen, AES nonces/salts, wallet seeds, master keys) uses OS CSPRNG; non-cryptographic RNG restricted to jitter, shuffling, and tests


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