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