@polkadot/util-crypto/scrypt/fromU8a.js

A collection of useful crypto utilities for @polkadot

import { u8aToBn } from '@polkadot/util';
import { BN_LE_OPTS } from '../bn.js';
import { DEFAULT_PARAMS } from './defaults.js';
export function scryptFromU8a(data) {
    if (!(data instanceof Uint8Array)) {
        throw new Error('Expected input to be a Uint8Array');
    }
    // Ensure the input is exactly 44 bytes: 32 for salt + 3 * 4 for N, p, r
    if (data.length < 32 + 12) {
        throw new Error(`Invalid input length: expected 44 bytes, found ${data.length}`);
    }
    const salt = data.subarray(0, 32);
    const N = u8aToBn(data.subarray(32, 36), BN_LE_OPTS).toNumber();
    const p = u8aToBn(data.subarray(36, 40), BN_LE_OPTS).toNumber();
    const r = u8aToBn(data.subarray(40, 44), BN_LE_OPTS).toNumber();
    // FIXME At this moment we assume these to be fixed params, this is not a great idea
    // since we lose flexibility and updates for greater security. However we need some
    // protection against carefully-crafted params that can eat up CPU since these are user
    // inputs. So we need to get very clever here, but atm we only allow the defaults
    // and if no match, bail out
    if (N !== DEFAULT_PARAMS.N || p !== DEFAULT_PARAMS.p || r !== DEFAULT_PARAMS.r) {
        throw new Error('Invalid injected scrypt params found');
    }
    return { params: { N, p, r }, salt };
}