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2.1.4 • Public • Published

MetaMask fork

This is a temporary fork of the @scure/bip39 package created by the MetaMask team. Please do not use this package for other projects, use @scure/bip39 directly instead. We are not interested in maintaining this long-term. We will not be accepting community issues or PRs.


Secure, audited & minimal implementation of BIP39 mnemonic phrases.

Compared to popular bip39 package, scure-bip39:

  • Is 491KB all-bundled instead of 1.3MB
  • Uses 2 dependencies instead of 15
  • Wordlists are 157KB instead of 315KB
  • Had an external security audit by Cure53 on Jan 5, 2022

Check out scure-bip32 if you need hierarchical deterministic wallets ("HD Wallets").

This library belongs to scure

scure — secure audited packages for every use case.

  • Independent security audits
  • All releases are signed with PGP keys
  • Check out all libraries: base, bip32, bip39


npm install @metamask/scure-bip39


yarn add @metamask/scure-bip39

import * as bip39 from '@metamask/scure-bip39';
import { wordlist } from '@metamask/scure-bip39/wordlists/english';

// Generate x random words. Uses Cryptographically-Secure Random Number Generator.
const mn = bip39.generateMnemonic(wordlist);

// Reversible: Converts mnemonic string to raw entropy in form of byte array.
const ent = bip39.mnemonicToEntropy(mn, wordlist)

// Reversible: Converts raw entropy in form of byte array to mnemonic string.
bip39.entropyToMnemonic(ent, wordlist);

// Validates mnemonic for being 12-24 words contained in `wordlist`.
bip39.validateMnemonic(mn, wordlist);

// Irreversible: Uses KDF to derive 64 bytes of key data from mnemonic + optional password.
await bip39.mnemonicToSeed(mn, 'password');
bip39.mnemonicToSeedSync(mn, 'password');

This submodule contains the word lists defined by BIP39 for Czech, English, French, Italian, Japanese, Korean, Simplified and Traditional Chinese, and Spanish. These are not imported by default, as that would increase bundle sizes too much. Instead, you should import and use them explicitly.

function generateMnemonic(wordlist: string[], strength?: number): string;
function mnemonicToEntropy(mnemonic: string, wordlist: string[]): Uint8Array;
function entropyToMnemonic(entropy: Uint8Array, wordlist: string[]): string;
function validateMnemonic(mnemonic: string, wordlist: string[]): boolean;
function mnemonicToSeed(mnemonic: string, passphrase?: string): Promise<Uint8Array>;
function mnemonicToSeedSync(mnemonic: string, passphrase?: string): Uint8Array;

All wordlists:

import { wordlist } from '@metamask/scure-bip39/wordlists/czech';
import { wordlist } from '@metamask/scure-bip39/wordlists/english';
import { wordlist } from '@metamask/scure-bip39/wordlists/french';
import { wordlist } from '@metamask/scure-bip39/wordlists/italian';
import { wordlist } from '@metamask/scure-bip39/wordlists/japanese';
import { wordlist } from '@metamask/scure-bip39/wordlists/korean';
import { wordlist } from '@metamask/scure-bip39/wordlists/simplified-chinese';
import { wordlist } from '@metamask/scure-bip39/wordlists/spanish';
import { wordlist } from '@metamask/scure-bip39/wordlists/traditional-chinese';


The library has been audited by Cure53 on Jan 5, 2022. Check out the audit PDF & URL. See changes since audit.

  1. The library was initially developed for js-ethereum-cryptography
  2. At commit ae00e6d7, it was extracted to a separate package called micro-bip39
  3. After the audit we've decided to use NPM namespace for security. Since @micro namespace was taken, we've renamed the package to @scure/bip39
  4. As a modified fork for use by MetaMask, the package name is changed to @metamask/scure-bip39.


MIT License

Copyright (c) 2022 Patricio Palladino, Paul Miller (paulmillr.com)

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