127 lines
3.9 KiB
TypeScript
127 lines
3.9 KiB
TypeScript
/**
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* HMAC: RFC2104 message authentication code.
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* @module
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*/
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import {
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abytes,
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aexists,
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ahash,
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aoutput,
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clean,
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type CHash,
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type Hash,
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type TArg,
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type TRet,
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} from './utils.ts';
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/**
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* Internal class for HMAC.
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* Accepts any byte key, although RFC 2104 §3 recommends keys at least
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* `HashLen` bytes long.
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*/
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export class _HMAC<T extends Hash<T>> implements Hash<_HMAC<T>> {
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oHash: T;
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iHash: T;
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blockLen: number;
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outputLen: number;
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canXOF = false;
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private finished = false;
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private destroyed = false;
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constructor(hash: TArg<CHash>, key: TArg<Uint8Array>) {
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ahash(hash);
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abytes(key, undefined, 'key');
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this.iHash = hash.create() as T;
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if (typeof this.iHash.update !== 'function')
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throw new Error('Expected instance of class which extends utils.Hash');
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this.blockLen = this.iHash.blockLen;
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this.outputLen = this.iHash.outputLen;
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const blockLen = this.blockLen;
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const pad = new Uint8Array(blockLen);
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// blockLen can be bigger than outputLen
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pad.set(key.length > blockLen ? hash.create().update(key).digest() : key);
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for (let i = 0; i < pad.length; i++) pad[i] ^= 0x36;
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this.iHash.update(pad);
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// By doing update (processing of the first block) of the outer hash here,
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// we can re-use it between multiple calls via clone.
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this.oHash = hash.create() as T;
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// Undo internal XOR && apply outer XOR
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for (let i = 0; i < pad.length; i++) pad[i] ^= 0x36 ^ 0x5c;
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this.oHash.update(pad);
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clean(pad);
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}
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update(buf: TArg<Uint8Array>): this {
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aexists(this);
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this.iHash.update(buf);
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return this;
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}
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digestInto(out: TArg<Uint8Array>): void {
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aexists(this);
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aoutput(out, this);
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this.finished = true;
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const buf = out.subarray(0, this.outputLen);
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// Reuse the first outputLen bytes for the inner digest; the outer hash consumes them before
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// overwriting that same prefix with the final tag, leaving any oversized tail untouched.
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this.iHash.digestInto(buf);
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this.oHash.update(buf);
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this.oHash.digestInto(buf);
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this.destroy();
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}
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digest(): TRet<Uint8Array> {
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const out = new Uint8Array(this.oHash.outputLen);
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this.digestInto(out);
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return out as TRet<Uint8Array>;
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}
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_cloneInto(to?: _HMAC<T>): _HMAC<T> {
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// Create new instance without calling constructor since the key
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// is already in state and we don't know it.
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to ||= Object.create(Object.getPrototypeOf(this), {});
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const { oHash, iHash, finished, destroyed, blockLen, outputLen } = this;
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to = to as this;
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to.finished = finished;
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to.destroyed = destroyed;
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to.blockLen = blockLen;
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to.outputLen = outputLen;
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to.oHash = oHash._cloneInto(to.oHash);
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to.iHash = iHash._cloneInto(to.iHash);
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return to;
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}
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clone(): _HMAC<T> {
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return this._cloneInto();
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}
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destroy(): void {
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this.destroyed = true;
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this.oHash.destroy();
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this.iHash.destroy();
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}
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}
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/**
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* HMAC: RFC2104 message authentication code.
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* @param hash - function that would be used e.g. sha256
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* @param key - authentication key bytes
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* @param message - message bytes to authenticate
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* @returns Authentication tag bytes.
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* @example
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* Compute an RFC 2104 HMAC.
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* ```ts
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* import { hmac } from '@noble/hashes/hmac.js';
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* import { sha256 } from '@noble/hashes/sha2.js';
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* const mac = hmac(sha256, new Uint8Array([1, 2, 3]), new Uint8Array([4, 5, 6]));
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* ```
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*/
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type HmacFn = {
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(hash: TArg<CHash>, key: TArg<Uint8Array>, message: TArg<Uint8Array>): TRet<Uint8Array>;
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create(hash: TArg<CHash>, key: TArg<Uint8Array>): TRet<_HMAC<any>>;
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};
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export const hmac: TRet<HmacFn> = /* @__PURE__ */ (() => {
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const hmac_ = ((
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hash: TArg<CHash>,
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key: TArg<Uint8Array>,
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message: TArg<Uint8Array>
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): TRet<Uint8Array> => new _HMAC<any>(hash, key).update(message).digest()) as TRet<HmacFn>;
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hmac_.create = (hash: TArg<CHash>, key: TArg<Uint8Array>): TRet<_HMAC<any>> =>
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new _HMAC<any>(hash, key) as TRet<_HMAC<any>>;
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return hmac_;
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})();
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