@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 { ALLOWED_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();
    if (N > (1 << 20) || p > 4 || r > 16) {
        throw new Error('Scrypt parameters exceed safe limits');
    }
    const isAllowed = ALLOWED_PARAMS.some((preset) => preset.N === N && preset.p === p && preset.r === r);
    if (!isAllowed) {
        throw new Error('Invalid injected scrypt params found');
    }
    return { params: { N, p, r }, salt };
}