@lanitlabs/pqc-lnqc714

Post-Quantum Key Encapsulation Mechanism (KEM) — LPN-based key agreement with LDPC error correction.
Constant-time Rust/WASM engine targeting browsers, Node.js, and Edge runtimes.

npm install @lanitlabs/pqc-lnqc714

Overview

LNQC-714 is a KEM whose security reduces to the hardness of the fixed-weight Learning Parity with Noise (LPN) problem over GF(2). A Low-Density Parity-Check (LDPC) code with a Gallager bit-flipping decoder absorbs the sparse LPN noise, achieving 0% decryption failure at the security parameters:

| Parameter | Value | |---|---| | LPN dimension | n = 512 | | LPN samples | m = 512 | | Noise weight | w = 4 | | LDPC codeword | 2048 bits | | LDPC data | 256 bits | | Decoder | Gallager bit-flipping (50 iters) | | Public key | 262 656 bytes | | Ciphertext | 1 050 624 bytes |

All operations execute in constant-time binary matrix algebra modulo 2 — no data-dependent branching, no rejection sampling, no modular arithmetic. This provides architectural immunity to cache-timing and power-analysis side-channel attacks.

API

import LNQC from '@lanitlabs/pqc-lnqc714';

// ── Key Generation ──────────────────────────────────────────
const keys = LNQC.keyGen();
// keys.publicKeyA:  Uint8Array  (512 × 512 bits, row-major)
// keys.publicKeyT:  Uint8Array  (512 bits)
// keys.privateKey:  Uint8Array  (512 bits)

// ── Encapsulation ───────────────────────────────────────────
const msg = LNQC.randomBits(256);            // 256-bit shared secret
const ct = LNQC.encapsulate(
  keys.publicKeyA,
  keys.publicKeyT,
  msg,
);
// ct.u:  Uint8Array  (2048 × 512 bits)
// ct.v:  Uint8Array  (2048 bits)
// ct.byteLength:  number

// ── Decapsulation ───────────────────────────────────────────
const recovered = LNQC.decapsulate(
  keys.privateKey,
  ct.u,
  ct.v,
);
// recovered equals `msg` (LDPC decoder corrects LPN noise)

// ── Constant-Time Verification ──────────────────────────────
const match = LNQC.constantTimeVerify(secretA, secretB);
// Returns true/false in constant time (subtle::ConstantTimeEq)

Parameter getters

LNQC.getNCols()            // 512
LNQC.getMRows()            // 512
LNQC.getNoiseWeight()      // 4
LNQC.getLdpcDataBits()     // 256
LNQC.getLdpcCodewordBits() // 2048

Architecture

┌──────────────────────────────────────────────────────────┐
│  JS/TS (consumer)                                       │
│    import LNQC from '@lanitlabs/pqc-lnqc714'            │
└─────────────────────┬────────────────────────────────────┘
                      │
┌─────────────────────▼────────────────────────────────────┐
│  dist/index.js  (dynamic loader)                         │
│    Node.js  →  pkg/node/pqc_lnqc714.js                  │
│    Browser  →  pkg/browser/pqc_lnqc714.js               │
└─────────────────────┬────────────────────────────────────┘
                      │ wasm-bindgen
┌─────────────────────▼────────────────────────────────────┐
│  Rust/WASM  (src/crypto.rs)                              │
│    • Secure RNG via getrandom (os.urandom)               │
│    • Regular LDPC construction (col_weight=15)           │
│    • Gallager bit-flipping decoder                       │
│    • Sparse R_indices optimization                       │
│    • subtle::ConstantTimeEq for verification             │
└──────────────────────────────────────────────────────────┘

Security

• LPN hardness: No known sub-exponential quantum algorithm.
• CSPRNG: All keys, noise vectors, and ephemeral randomness use getrandom (OS entropy / crypto.getRandomValues). No insecure PRNG (PCG, xorshift) is used for security-critical data.
• Constant-time: The subtle crate guards token comparison against timing side-channels.
• LDPC protection: Regular column-weight-15 parity-check matrix eliminates single-check failure modes.

License

MIT