nx_sha3_256_wasm.nx

nx_sha3_256_wasm.nx -- SHA-3-256 (FIPS 202) self-contained for WAT target. Sponge construction over Keccak-f[1600]: * State = 25 lanes of 64-bit (5x5 matrix), stored as 200 bytes little-endian * Rate r = 1088 bits = 136 bytes (SHA-3-256: capacity c = 512 bits) * Padding: append 0x06 then pad with zeros, set high bit of last byte (M || 0110 0... 0001 in bit order; the 0x06 = 01100000 in little-endian bit numbering = M || 01 || 10*1 per FIPS 202 §B.2) * Output: first 32 bytes of state Inlined Keccak-f[1600]: 24 rounds of theta, rho, pi, chi, iota. Each lane is 64-bit; we pack i64 in/out at byte level (LE) to keep the WAT codegen path narrow (no i64 loads through u8 pointers). API: nx_sha3_256_one_shot(msg_ptr, msg_len, state_ptr, out_ptr) -> i64 msg_ptr -- input bytes msg_len -- input length state_ptr -- >= 256 bytes scratch (200 for state + 56 slack) out_ptr -- 32 bytes for digest Verified against FIPS 202 / NIST CAVP test vectors (empty + "abc" + "The quick brown fox..." per common reference set). license_tier: INDEPENDENT_REDERIVE genealogy_id: international-research-sources/nist/fips_202 lineage_id: nishi_sha3_256_wasm_q1