awaforge

cmac

Apache-2.0Release 1L3

AES-CMAC (SP 800-38B / RFC 4493) — deterministic MAC based on AES, TDES rejected.

Module cmac | Source packages/front/fw/src/crypto/mode/cmac.js | Deps bitArray, aes | Worker-safe yes

Default 128-bit tag, truncatable to 32-128 via truncatedMac (SP 800-38B §6.4 minimum 32 bits).

Resolve

const cmac = runtime.resolve('cmac');
// Returns: { mac, verify, truncatedMac, truncatedVerify, _internal }

API

Method Signature Returns
mac(prf, msgBa) — 128-bit tag
verify(prf, msgBa, tagBa) — boolean (constant-time)
truncatedMac(prf, msgBa, tagLen) — Truncated tag tagLen ∈ [32, 128]
truncatedVerify(prf, msgBa, tagBa, tagLen) — boolean
_internal.{subkeys} — Debug primitives

Examples

const { aes, cmac, bitArray } = fw.runtime.resolveAll(['aes', 'cmac', 'bitArray']);

const cipher = aes.fn(keyWords);
const msg = bitArray.ui8_to_ba(new TextEncoder().encode('Hello, CMAC!'));

const tag = cmac.mac(cipher, msg);                           // 128 bits
const ok  = cmac.verify(cipher, msg, tag);                   // true

const tag64 = cmac.truncatedMac(cipher, msg, 64);            // 64 bits
const ok64  = cmac.truncatedVerify(cipher, msg, tag64, 64);

TDES rejected

const tdesCipher = { encrypt: ..., blockSize: 8 };           // mock
cmac.mac(tdesCipher, msg);   // false + console.warn('DEPRECATED: cmac: non-AES block cipher (e.g. TDES)')

Worker Usage

const worker = fw.createWorker(
    function ({ libs, args }) {
        const cipher = libs.aes.fn(args[0]);
        self.postMessage(libs.cmac.mac(cipher, args[1]));
    },
    { dependencies: ['aes', 'cmac'], args: [keyWords, msgBa] }
);

Notes

  • TDES rejected: prf.blockSize !== 16 → false + DEPRECATED warn (SP 800-131A §2.4 + SP 800-38B §5.1).
  • tagLen < 32 → WEAK warn (SP 800-38B §6.4 recommended minimum).
  • verify constant-time via bitArray.equal.

See also