77 lines
2.7 KiB
TypeScript
77 lines
2.7 KiB
TypeScript
import { assertHash, Hash, CHash, Input, toBytes } from './utils';
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// HMAC (RFC 2104)
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class HMAC<T extends Hash<T>> extends 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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private finished = false;
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private destroyed = false;
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constructor(hash: CHash, _key: Input) {
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super();
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assertHash(hash);
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const key = toBytes(_key);
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this.iHash = hash.create() as T;
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if (!(this.iHash instanceof Hash))
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throw new TypeError('Expected instance of class which extends utils.Hash');
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const blockLen = (this.blockLen = this.iHash.blockLen);
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this.outputLen = this.iHash.outputLen;
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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 > this.iHash.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 first block) of outer hash here 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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pad.fill(0);
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}
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update(buf: Input) {
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if (this.destroyed) throw new Error('instance is destroyed');
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this.iHash.update(buf);
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return this;
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}
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digestInto(out: Uint8Array) {
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if (this.destroyed) throw new Error('instance is destroyed');
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if (!(out instanceof Uint8Array) || out.length !== this.outputLen)
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throw new Error('HMAC: Invalid output buffer');
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if (this.finished) throw new Error('digest() was already called');
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this.finished = true;
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this.iHash.digestInto(out);
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this.oHash.update(out);
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this.oHash.digestInto(out);
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this.destroy();
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}
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digest() {
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const out = new Uint8Array(this.oHash.outputLen);
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this.digestInto(out);
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return out;
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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 key 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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destroy() {
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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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export const hmac = (hash: CHash, key: Input, message: Input): Uint8Array =>
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new HMAC<any>(hash, key).update(message).digest();
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hmac.create = (hash: CHash, key: Input) => new HMAC<any>(hash, key);
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hmac.init = hmac.create;
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