Replace create hash with sha.js

[webmaster128]

Based on #172 (merge #172 first).

Closes #170

Turns out this is not enought to get create-hash out of the dependency tree because pbkdf2 uses it. However, it is possible to implement pbkdf2 manually or get that fixed in the next step.

[junderw]

Made a quick dirty impl of pbkdf2 using sha.js with SHA512, 64 dlen, and 2048 iterations hard coded. It was 5x~6x slower :-|

... we should probably section this off to a browser section... People in Node should not have to suffer even a 2x slowdown because of the browser.

import * as sha from 'sha.js';

const sha512 = (data: Buffer | string): Buffer => {
  return sha('sha512')
    .update(data)
    .digest();
};

const xorBuf = (a: Buffer, b: Buffer): Buffer => {
  const ret = Buffer.allocUnsafe(a.length);
  for (let i = 0; i < a.length; i++) {
    ret[i] = a[i] ^ b[i];
  }
  return ret;
};

const hmac = (data: Buffer | string, key: Buffer | string): Buffer => {
  const k = key.length > 128 ? sha512(key) : Buffer.from(key as any, 'utf8');
  const buf = Buffer.alloc(128);
  k.copy(buf);
  const oKey = Buffer.from(buf);
  const iKey = Buffer.from(buf);
  for (let i = 0; i < 128; i++) {
    oKey[i] = oKey[i] ^ 0x5c;
    iKey[i] = iKey[i] ^ 0x36;
  }
  return sha512(
    Buffer.concat([
      oKey,
      sha512(Buffer.concat([iKey, Buffer.from(data as any, 'utf8')])),
    ]),
  );
};

const ITERS = 2048;

export function pbkdf2(
  password: Buffer | string,
  salt: Buffer | string,
): Buffer {
  const UArray = [];
  UArray.push(
    hmac(
      Buffer.concat([
        Buffer.from(salt as any, 'utf8'),
        Buffer.from([0, 0, 0, 1]),
      ]),
      password,
    ),
  );
  let ret = UArray[0];
  for (let i = 1; i < ITERS; i++) {
    const hash = hmac(UArray[i - 1], password);
    UArray.push(hash);
    ret = xorBuf(ret, hash);
  }
  return ret;
}

[webmaster128]

... we should probably section this off to a browser section... People in Node should not have to suffer even a 2x slowdown because of the browser.

I doubt "browsers" is the right category. JS environments with/without Crypto APIs is probably the better classification. SubtleCrypto is available in Node.js 15.

It should not be too hard to come up with a pbkdf2 implementation that uses

1. SubtleCrypto
2. Node.js crypto module
3. Pure-JS fallback

as long as only SHA2 is needed.

[junderw]

I am not comfortable raising the requirement of NodeJS above v14 right now, so SubtleCrypto for Node is not possible.

[junderw]

Maybe after v12 EOL 2022-04-30

[webmaster128]

Sure, me neither. But you can have an implementation that uses 1., 2. or 3. depending on availability.

[webmaster128]

So my current thinking given your input is reimplementing pbkdf2

• in TypeScript
• supporting SHA2 only
• targeting reasonabily modern JS environments(native async/await and Uint8Array support)
• removal of the sync variant
• using SubtleCrypto, Node.js crypto module and pure-JS fallback depending on availability
• using the same SHA2 implementation for pbkdf2 and deriveChecksumBits

[infodusha]

Any chance this change will be merged?

[webmaster128]

I'm not planning to continue working on this. But feel free to use my commits if you want to finalize it.

[paulmillr]

not relevant anymore https://github.com/bitcoinjs/bip39/blob/a7ecbfe2e60d0214ce17163d610cad9f7b23140c/package.json#L38