/**
* PBKDF (RFC 2898). Can be used to create a key from password and salt.
* @module
*/
import { hmac } from './hmac.ts';
// prettier-ignore
import {
ahash, anumber,
asyncLoop, checkOpts, clean, createView, kdfInputToBytes,
type CHash,
type Hash,
type KDFInput,
type TArg,
type TRet
} from './utils.ts';
/**
* PBKDF2 options:
* * c: iterations, should probably be higher than 100_000
* * dkLen: desired length of derived key in bytes, must be `>= 1` per RFC 8018 §5.2
* * asyncTick: max time in ms for which async function can block execution
*/
export type Pbkdf2Opt = {
/** Iteration count. Higher values increase CPU cost. */
c: number;
/** Desired derived key length in bytes, must be `>= 1` per RFC 8018 §5.2. */
dkLen?: number;
/** Max scheduler block time in milliseconds for the async variant. */
asyncTick?: number;
};
// Common start and end for sync/async functions
function pbkdf2Init(
hash: TArg<CHash>,
_password: TArg<KDFInput>,
_salt: TArg<KDFInput>,
_opts: TArg<Pbkdf2Opt>
) {
ahash(hash);
const opts = checkOpts({ dkLen: 32, asyncTick: 10 }, _opts);
const { c, dkLen, asyncTick } = opts;
anumber(c, 'c');
anumber(dkLen, 'dkLen');
anumber(asyncTick, 'asyncTick');
if (c < 1) throw new Error('iterations (c) must be >= 1');
// RFC 8018 §5.2 defines `dkLen` as "a positive integer".
if (dkLen < 1) throw new Error('"dkLen" must be >= 1');
// RFC 8018 §5.2 step 1 requires rejecting oversize `dkLen`
// before allocating the destination buffer.
if (dkLen > (2 ** 32 - 1) * hash.outputLen) throw new Error('derived key too long');
const password = kdfInputToBytes(_password, 'password');
const salt = kdfInputToBytes(_salt, 'salt');
// DK = PBKDF2(PRF, Password, Salt, c, dkLen);
const DK = new Uint8Array(dkLen);
// U1 = PRF(Password, Salt + INT_32_BE(i))
const PRF = hmac.create(hash, password);
// Cache PRF(P, S || ...) prefix state so each block only appends INT_32_BE(i).
const PRFSalt = PRF._cloneInto().update(salt);
return { c, dkLen, asyncTick, DK, PRF, PRFSalt };
}
function pbkdf2Output<T extends Hash<T>>(
PRF: TArg<Hash<T>>,
PRFSalt: TArg<Hash<T>>,
DK: TArg<Uint8Array>,
prfW: TArg<Hash<T> | undefined>,
u: TArg<Uint8Array>
): TRet<Uint8Array> {
// Shared sync/async cleanup point: wipe transient PRF state
// while preserving the derived key buffer.
PRF.destroy();
PRFSalt.destroy();
if (prfW) prfW.destroy();
clean(u);
return DK as TRet<Uint8Array>;
}
/**
* PBKDF2-HMAC: RFC 8018 key derivation function.
* @param hash - hash function that would be used e.g. sha256
* @param password - password from which a derived key is generated;
* JS string inputs are UTF-8 encoded first
* @param salt - cryptographic salt; JS string inputs are UTF-8 encoded first
* @param opts - PBKDF2 work factor and output settings. `dkLen`, if provided,
* must be `>= 1` per RFC 8018 §5.2. See {@link Pbkdf2Opt}.
* @returns Derived key bytes.
* @throws If the PBKDF2 iteration count or derived-key settings are invalid. {@link Error}
* @example
* PBKDF2-HMAC: RFC 2898 key derivation function.
* ```ts
* import { pbkdf2 } from '@noble/hashes/pbkdf2.js';
* import { sha256 } from '@noble/hashes/sha2.js';
* const key = pbkdf2(sha256, 'password', 'salt', { dkLen: 32, c: Math.pow(2, 18) });
* ```
*/
export function pbkdf2(
hash: TArg<CHash>,
password: TArg<KDFInput>,
salt: TArg<KDFInput>,
opts: TArg<Pbkdf2Opt>
): TRet<Uint8Array> {
const { c, dkLen, DK, PRF, PRFSalt } = pbkdf2Init(hash, password, salt, opts);
let prfW: any; // Working copy
const arr = new Uint8Array(4);
const view = createView(arr);
const u = new Uint8Array(PRF.outputLen);
// DK = T1 + T2 + ⋯ + Tdklen/hlen
for (let ti = 1, pos = 0; pos < dkLen; ti++, pos += PRF.outputLen) {
// Ti = F(Password, Salt, c, i)
// The last Ti view can be shorter than hLen, which applies
// RFC 8018 §5.2 step 4's T_l<0..r-1> truncation without extra copies.
const Ti = DK.subarray(pos, pos + PRF.outputLen);
view.setInt32(0, ti, false);
// F(Password, Salt, c, i) = U1 ^ U2 ^ ⋯ ^ Uc
// U1 = PRF(Password, Salt + INT_32_BE(i))
(prfW = PRFSalt._cloneInto(prfW)).update(arr).digestInto(u);
Ti.set(u.subarray(0, Ti.length));
for (let ui = 1; ui < c; ui++) {
// Uc = PRF(Password, Uc−1)
PRF._cloneInto(prfW).update(u).digestInto(u);
for (let i = 0; i < Ti.length; i++) Ti[i] ^= u[i];
}
}
return pbkdf2Output(PRF, PRFSalt, DK, prfW, u);
}
/**
* PBKDF2-HMAC: RFC 8018 key derivation function. Async version.
* @param hash - hash function that would be used e.g. sha256
* @param password - password from which a derived key is generated;
* JS string inputs are UTF-8 encoded first
* @param salt - cryptographic salt; JS string inputs are UTF-8 encoded first
* @param opts - PBKDF2 work factor and output settings. `dkLen`, if provided,
* must be `>= 1` per RFC 8018 §5.2. `asyncTick` is only a local
* scheduler-yield knob for this JS wrapper, not part of RFC 8018.
* See {@link Pbkdf2Opt}.
* @returns Promise resolving to derived key bytes.
* @throws If the PBKDF2 iteration count or derived-key settings are invalid. {@link Error}
* @example
* PBKDF2-HMAC: RFC 2898 key derivation function.
* ```ts
* import { pbkdf2Async } from '@noble/hashes/pbkdf2.js';
* import { sha256 } from '@noble/hashes/sha2.js';
* const key = await pbkdf2Async(sha256, 'password', 'salt', { dkLen: 32, c: 500_000 });
* ```
*/
export async function pbkdf2Async(
hash: TArg<CHash>,
password: TArg<KDFInput>,
salt: TArg<KDFInput>,
opts: TArg<Pbkdf2Opt>
): Promise<TRet<Uint8Array>> {
const { c, dkLen, asyncTick, DK, PRF, PRFSalt } = pbkdf2Init(hash, password, salt, opts);
let prfW: any; // Working copy
const arr = new Uint8Array(4);
const view = createView(arr);
const u = new Uint8Array(PRF.outputLen);
// DK = T1 + T2 + ⋯ + Tdklen/hlen
for (let ti = 1, pos = 0; pos < dkLen; ti++, pos += PRF.outputLen) {
// Ti = F(Password, Salt, c, i)
// The last Ti view can be shorter than hLen, which applies
// RFC 8018 §5.2 step 4's T_l<0..r-1> truncation without extra copies.
const Ti = DK.subarray(pos, pos + PRF.outputLen);
view.setInt32(0, ti, false);
// F(Password, Salt, c, i) = U1 ^ U2 ^ ⋯ ^ Uc
// U1 = PRF(Password, Salt + INT_32_BE(i))
(prfW = PRFSalt._cloneInto(prfW)).update(arr).digestInto(u);
Ti.set(u.subarray(0, Ti.length));
await asyncLoop(c - 1, asyncTick, () => {
// Uc = PRF(Password, Uc−1)
PRF._cloneInto(prfW).update(u).digestInto(u);
for (let i = 0; i < Ti.length; i++) Ti[i] ^= u[i];
});
}
return pbkdf2Output(PRF, PRFSalt, DK, prfW, u);
}