nx_kyber_msg_codec_wasm.nx

nx_kyber_msg_codec_wasm.nx -- 1-bit message <-> polynomial codec. FIPS 203 §4.2.4 Compress_1 / Decompress_1 specialized for the K-PKE message-embedding step. Each bit of the 32-byte message becomes one coefficient of a 256-coef polynomial (32 * 8 = 256 bits). Encoding direction (msg -> poly, used in K-PKE encrypt step 10): For each bit b in msg: coefficient = b * Decompress_1(1) = b * round(q/2) = b * 1665 (since (3329 + 1) / 2 = 1665) Decoding direction (poly -> msg, used in K-PKE decrypt step 9): For each coefficient c (canonical [0, q)): bit = Compress_1(c) = round((2 * c) / q) mod 2 = ((c << 1) + q/2) / q mod 2 = ((2*c + 1665) / 3329) & 1 The decoding boundary is c = q/2 = 1665 (and -1665 = 1664 in [0,q)). Coefficients close to 0 decode to bit 0; coefficients close to q/2 decode to bit 1. This is the error-correcting margin that makes K-PKE robust to the small noise added during encrypt. API: nx_kyber_msg_to_poly(poly_out, msg_32) -> i64 nx_kyber_msg_from_poly(msg_out, poly) -> i64 Verified: KAT round-trip on random 32-byte messages + boundary cases. license_tier: INDEPENDENT_REDERIVE genealogy_id: international-research-sources/nist/fips_203 lineage_id: nishi_kyber_msg_codec_wasm_q1 safe_shift_audit: no 64-bit rotations in this module