ethereum-cryptography

This package contains all pure-js cryptographic primitives normally used when developing Javascript / TypeScript applications and tools for Ethereum.

The cryptographic primitives included are:

Hashes: SHA256, keccak-256, RIPEMD160, BLAKE2b
KDFs: PBKDF2, Scrypt
CSPRNG (Cryptographically strong pseudorandom number generator)
secp256k1 curve
BIP32 HD Keygen
BIP39 Mnemonic phrases
AES Encryption

October 2021 update: We're releasing experimental version 0.2 of the package. The module has been completely rewritten:

~6x smaller: 4,000 lines of code instead of 22,438 (with all deps); 185KB instead of 755KB
3 dependencies (pending an audit) instead of 38
Same functionality, all old APIs remain the same except for two breaking changes:
1. We return Uint8Array from all methods that worked with Buffer before. Buffer has never been supported in browsers, while Uint8Arrays are supported natively in both browsers and node.js. See Upgrading
2. We target runtimes with bigint support, which is Chrome 67+, Edge 79+, Firefox 68+, Safari 14+, node.js 10+. If you need to support older runtimes, use ethereum-cryptography@0.1
3. If you've used secp256k1, rename it to secp256k1-compat
The new module has not been audited yet, but it's in the process of getting the audit. Use it at your own risk

Usage

Use NPM / Yarn in node.js / browser:

# NPM
npm install ethereum-cryptography@next

# Yarn
yarn add ethereum-cryptography@next

See browser usage for information on using the package with major Javascript bundlers. It is tested with Webpack, Rollup, Parcel and Browserify.

This package has no single entry-point, but submodule for each cryptographic primitive. Read each primitive's section of this document to learn how to use them.

The reason for this is that importing everything from a single file will lead to huge bundles when using this package for the web. This could be avoided through tree-shaking, but the possibility of it not working properly on one of the supported bundlers is too high.

// Hashes
const { sha256 } = require("ethereum-cryptography/sha256");
const { keccak256 } = require("ethereum-cryptography/keccak");
const { ripemd160 } = require("ethereum-cryptography/ripemd160");
const { blake2b } = require("ethereum-cryptography/blake2b");

// KDFs
const { pbkdf2Sync } = require("ethereum-cryptography/pbkdf2");
const { scryptSync } = require("ethereum-cryptography/scrypt");

// Random
const { getRandomBytesSync } = require("ethereum-cryptography/random");

// AES encryption
const { encrypt } = require("ethereum-cryptography/aes");

// secp256k1 elliptic curve operations
const { createPrivateKeySync, ecdsaSign } = require("ethereum-cryptography/secp256k1");

// BIP32 HD Keygen, BIP39 Mnemonic Phrases
const { HDKey } = require("ethereum-cryptography/hdkey");
const { generateMnemonic } = require("ethereum-cryptography/bip39");
const { wordlist } = require("ethereum-cryptography/bip39/wordlists/english");

// utilities
const { hexToBytes, toHex, utf8ToBytes } = require("ethereum-cryptography/utils");

Hashes: SHA256, keccak-256, RIPEMD160, BLAKE2b

function sha256(msg: Uint8Array): Uint8Array;
function sha512(msg: Uint8Array): Uint8Array;
function keccak256(msg: Uint8Array): Uint8Array;
function ripemd160(msg: Uint8Array): Uint8Array;
function blake2b(msg: Uint8Array, outputLength = 64): Uint8Array;

Exposes following cryptographic hash functions:

SHA2 (SHA256, SHA512)
keccak-256 variant of SHA3 (also keccak224, keccak384, and keccak512)
RIPEMD160
BLAKE2b

const { sha256 } = require("ethereum-cryptography/sha256");
const { sha512 } = require("ethereum-cryptography/sha512");
const { keccak256, keccak224, keccak384, keccak512 } = require("ethereum-cryptography/keccak");
const { ripemd160 } = require("ethereum-cryptography/ripemd160");
const { blake2b } = require("ethereum-cryptography/blake2b");

sha256(Uint8Array.from([1, 2, 3]))

// Can be used with strings
const { utf8ToBytes } = require("ethereum-cryptography/utils");
sha256(utf8ToBytes("abc"))

// If you need hex
const { bytesToHex as toHex } = require("ethereum-cryptography/utils");
toHex(sha256(utf8ToBytes("abc")))

KDFs: PBKDF2, Scrypt

function pbkdf2(password: Uint8Array, salt: Uint8Array, iterations: number, keylen: number, digest: string): Promise<Uint8Array>;
function pbkdf2Sync(password: Uint8Array, salt: Uint8Array, iterations: number, keylen: number, digest: string): Uint8Array;
function scrypt(password: Uint8Array, salt: Uint8Array, N: number, p: number, r: number, dkLen: number): Promise<Uint8Array>;
function scryptSync(password: Uint8Array, salt: Uint8Array, N: number, p: number, r: number, dkLen: number): Uint8Array;

The pbkdf2 submodule has two functions implementing the PBKDF2 key derivation algorithm in synchronous and asynchronous ways. This algorithm is very slow, and using the synchronous version in the browser is not recommended, as it will block its main thread and hang your UI. The KDF supports sha256 and sha512 digests.

The scrypt submodule has two functions implementing the Scrypt key derivation algorithm in synchronous and asynchronous ways. This algorithm is very slow, and using the synchronous version in the browser is not recommended, as it will block its main thread and hang your UI.

Encoding passwords is a frequent source of errors. Please read these notes before using these submodules.

const { pbkdf2 } = require("ethereum-cryptography/pbkdf2");
const { utf8ToBytes } = require("ethereum-cryptography/utils");
// Pass Uint8Array, or convert strings to Uint8Array
console.log(await pbkdf2(utf8ToBytes("password"), utf8ToBytes("salt"), 131072, 32, "sha256"));

const { scryptSync } = require("ethereum-cryptography/scrypt");
const { utf8ToBytes } = require("ethereum-cryptography/utils");
console.log(await scrypt(utf8ToBytes("password"), utf8ToBytes("salt"), 262144, 8, 1, 32));

CSPRNG (Cryptographically strong pseudorandom number generator)

function getRandomBytes(bytes: number): Promise<Uint8Array>;
function getRandomBytesSync(bytes: number): Uint8Array;

The random submodule has functions to generate cryptographically strong pseudo-random data in synchronous and asynchronous ways.

Backed by crypto.getRandomValues in browser and by crypto.randomBytes in node.js. If backends are somehow not available, the module would throw an error and won't work, as keeping them working would be insecure.

const { getRandomBytesSync } = require("ethereum-cryptography/random");
console.log(getRandomBytesSync(32));

secp256k1 curve

function getPublicKey(privateKey: Uint8Array, isCompressed?: false): Uint8Array;
function getSharedSecret(privateKeyA: Uint8Array, publicKeyB: Uint8Array): Uint8Array;
function sign(msgHash: Uint8Array, privateKey: Uint8Array, opts?: Options): Promise<Uint8Array>;
function signSync(msgHash: Uint8Array, privateKey: Uint8Array, opts?: Options): Uint8Array;
function verify(signature: Uint8Array, msgHash: Uint8Array, publicKey: Uint8Array): boolean
function recoverPublicKey(msgHash: Uint8Array, signature: Uint8Array, recovery: number): Uint8Array | undefined;
function utils.randomPrivateKey(): Uint8Array;

The secp256k1 submodule provides a library for elliptic curve operations on the curve secp256k1. For detailed documentation, follow README of noble-secp256k1, which the module uses as a backend.

secp256k1 private keys need to be cryptographically secure random numbers with certain caracteristics. If this is not the case, the security of secp256k1 is compromised. We strongly recommend using utils.randomPrivateKey() to generate them.

const secp = require("ethereum-cryptography/secp256k1");
(async () => {
  // You pass either a hex string, or Uint8Array
  const privateKey = "6b911fd37cdf5c81d4c0adb1ab7fa822ed253ab0ad9aa18d77257c88b29b718e";
  const messageHash = "a33321f98e4ff1c283c76998f14f57447545d339b3db534c6d886decb4209f28";
  const publicKey = secp.getPublicKey(privateKey);
  const signature = await secp.sign(messageHash, privateKey);
  const isSigned = secp.verify(signature, messageHash, publicKey);
})();

Note: if you've been using ethereum-cryptography v0.1, it had different API. We're providing a compatibility layer for users who want to upgrade without hassle. Check out the legacy documentation.

BIP32 HD Keygen

This module exports a single class HDKey, which should be used like this:

const { HDKey } = require("ethereum-cryptography/hdkey");
const hdkey1 = HDKey.fromMasterSeed(seed);
const hdkey2 = HDKey.fromExtendedKey(base58key);
const hdkey3 = HDKey.fromJSON({ xpriv: string });

// props
[hdkey1.depth, hdkey1.index, hdkey1.chainCode];
console.log(hdkey2.privateKey, hdkey2.publicKey);
console.log(hdkey3.derive("m/0/2147483647'/1"));
const sig = hdkey3.sign(hash);
hdkey3.verify(hash, sig);

Note: chainCode property is essentially a private part of a secret "master" key, it should be guarded from unauthorized access.

The full API is:

class HDKey {
  public static HARDENED_OFFSET: number;
  public static fromMasterSeed(seed: Uint8Array, versions: Versions): HDKey;
  public static fromExtendedKey(base58key: string, versions: Versions): HDKey;
  public static fromJSON(json: { xpriv: string }): HDKey;

  readonly versions: Versions;
  readonly depth: number = 0;
  readonly index: number = 0;
  readonly chainCode: Uint8Array | null = null;
  readonly parentFingerprint: number = 0;

  get fingerprint(): number;
  get identifier(): Uint8Array | undefined;
  get pubKeyHash(): Uint8Array | undefined;
  get privateKey(): Uint8Array | null;
  get publicKey(): Uint8Array | null;
  get privateExtendedKey(): string;
  get publicExtendedKey(): string;

  derive(path: string): HDKey;
  deriveChild(index: number): HDKey;
  sign(hash: Uint8Array): Uint8Array;
  verify(hash: Uint8Array, signature: Uint8Array): boolean;
  wipePrivateData(): this;
}

interface Versions {
  private: number;
  public: number;
}

The hdkey submodule provides a library for keys derivation according to BIP32.

It has almost the exact same API than the version 1.x of hdkey from cryptocoinjs, but it's backed by this package's primitives, and has built-in TypeScript types. Its only difference is that it has to be be used with a named import. The implementation is loosely based on hdkey, which has MIT License.

BIP39 Mnemonic Seed Phrase

function generateMnemonic(wordlist: string[], strength: number = 128): string;
function mnemonicToEntropy(mnemonic: string, wordlist: string[]): Uint8Array;
function entropyToMnemonic(entropy: Uint8Array, wordlist: string[]): string;
function validateMnemonic(mnemonic: string, wordlist: string[]): boolean;
async function mnemonicToSeed(mnemonic: string, passphrase: string = ""): Promise<Uint8Array>;
function mnemonicToSeedSync(mnemonic: string, passphrase: string = ""): Uint8Array;

The bip39 submodule provides functions to generate, validate and use seed recovery phrases according to BIP39.

const { generateMnemonic } = require("ethereum-cryptography/bip39");
const { wordlist } = require("ethereum-cryptography/bip39/wordlists/english");
console.log(generateMnemonic(wordlist));

This submodule also 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.

The word lists are exported as a wordlist variable in each of these submodules:

ethereum-cryptography/bip39/wordlists/czech.js
ethereum-cryptography/bip39/wordlists/english.js
ethereum-cryptography/bip39/wordlists/french.js
ethereum-cryptography/bip39/wordlists/italian.js
ethereum-cryptography/bip39/wordlists/japanese.js
ethereum-cryptography/bip39/wordlists/korean.js
ethereum-cryptography/bip39/wordlists/simplified-chinese.js
ethereum-cryptography/bip39/wordlists/spanish.js
ethereum-cryptography/bip39/wordlists/traditional-chinese.js

AES Encryption

function encrypt(msg: Uint8Array, key: Uint8Array, iv: Uint8Array, mode = "aes-128-ctr", pkcs7PaddingEnabled = true): Promise<Uint8Array>;
function decrypt(cypherText: Uint8Array, key: Uint8Array, iv: Uint8Array, mode = "aes-128-ctr", pkcs7PaddingEnabled = true): Promise<Uint8Array>;

The aes submodule contains encryption and decryption functions implementing the Advanced Encryption Standard algorithm.

Encrypting with passwords

AES is not supposed to be used directly with a password. Doing that will compromise your users' security.

The key parameters in this submodule are meant to be strong cryptographic keys. If you want to obtain such a key from a password, please use a key derivation function like pbkdf2 or scrypt.

Operation modes

This submodule works with different block cipher modes of operation. If you are using this module in a new application, we recommend using the default.

While this module may work with any mode supported by OpenSSL, we only test it with aes-128-ctr, aes-128-cbc, and aes-256-cbc. If you use another module a warning will be printed in the console.

We only recommend using aes-128-cbc and aes-256-cbc to decrypt already encrypted data.

Padding plaintext messages

Some operation modes require the plaintext message to be a multiple of 16. If that isn't the case, your message has to be padded.

By default, this module automatically pads your messages according to PKCS#7. Note that this padding scheme always adds at least 1 byte of padding. If you are unsure what anything of this means, we strongly recommend you to use the defaults.

If you need to encrypt without padding or want to use another padding scheme, you can disable PKCS#7 padding by passing false as the last argument and handling padding yourself. Note that if you do this and your operation mode requires padding, encrypt will throw if your plaintext message isn't a multiple of 16.

This option is only present to enable the decryption of already encrypted data. To encrypt new data, we recommend using the default.

How to use the IV parameter

The iv parameter of the encrypt function must be unique, or the security of the encryption algorithm can be compromissed.

You can generate a new iv using the random module.

Note that to decrypt a value, you have to provide the same iv used to encrypt it.

How to handle errors with this module

Sensitive information can be leaked via error messages when using this module. To avoid this, you should make sure that the errors you return don't contain the exact reason for the error. Instead, errors must report general encryption/decryption failures.

Note that implementing this can mean catching all errors that can be thrown when calling on of this module's functions, and just throwing a new generic exception.

Example usage

const { encrypt } = require("ethereum-cryptography/aes");
const { hexToBytes, utf8ToBytes } = require("ethereum-cryptography/utils");

console.log(
  encrypt(
    utf8ToBytes("message"),
    hexToBytes("2b7e151628aed2a6abf7158809cf4f3c"),
    hexToBytes("f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff")
  )
);

Browser usage

Rollup setup

Using this library with Rollup requires the following plugins:

These can be used by setting your plugins array like this:

  plugins: [
    commonjs(),
    resolve({
      browser: true,
      preferBuiltins: false,
    }),
  ]

Legacy secp256k1 compatibility layer

Note: consider using secp256k1 instead; This module is only for users who upgraded from ethereum-cryptography v0.1. It could be removed in the future, but we're keeping it around for now, for backwards-compatibility.

The API of secp256k1-compat is the same as secp256k1-node:

const { createPrivateKeySync, ecdsaSign } = require("ethereum-cryptography/secp256k1-compat");
const msgHash = Uint8Array.from(
  "82ff40c0a986c6a5cfad4ddf4c3aa6996f1a7837f9c398e17e5de5cbd5a12b28",
  "hex"
);
const privateKey = createPrivateKeySync();
console.log(Uint8Array.from(ecdsaSign(msgHash, privateKey).signature));

Missing cryptographic primitives

This package intentionally excludes the the cryptographic primitives necessary to implement the following EIPs:

Feel free to open an issue if you want this decision to be reconsidered, or if you found another primitive that is missing.

Upgrading

Version 0.2 changes from 0.1:

Breaking: we target runtimes with bigint support, which is Chrome 67+, Edge 79+, Firefox 68+, Safari 14+, node.js 10+. If you need to support older runtimes, use ethereum-cryptography@0.1
Breaking: we return Uint8Array from all methods that worked with Buffer before. Buffer has never been supported in browsers, while Uint8Arrays are supported natively in both browsers and node.js:

const { sha256 } = require("ethereum-cryptography/sha256");

// Old usage
const hasho = sha256(Buffer.from("string", "utf8")).toString("hex");

// New usage
const { toHex } = require("ethereum-cryptography/utils");
const hashn = toHex(sha256("string"));

// If you have `Buffer` module and want to preserve it:
const hashb = Buffer.from(sha256("string"));
const hashbo = hashb.toString("hex");

Security

This library is in the process of getting a security audit.

License

ethereum-cryptography is released under The MIT License (MIT)

See LICENSE file.

hdkey is loosely based on hdkey, which had MIT License

PutriCitraKirana/js-ethereum-cryptography