js-libp2p-crypto/README.md

# js-libp2p-crypto

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> Crypto primitives for libp2p in JavaScript

This repo contains the JavaScript implementation of the crypto primitives needed for libp2p. This is based on this [go implementation](https://github.com/libp2p/go-libp2p-crypto).

## Lead Maintainer

[Friedel Ziegelmayer](https://github.com/dignifiedquire/)

## Table of Contents

- [js-libp2p-crypto](#js-libp2p-crypto)
  - [Lead Maintainer](#Lead-Maintainer)
  - [Table of Contents](#Table-of-Contents)
  - [Install](#Install)
  - [API](#API)
    - [`crypto.aes`](#cryptoaes)
      - [`crypto.aes.create(key, iv)`](#cryptoaescreatekey-iv)
        - [`decrypt(data)`](#decryptdata)
        - [`encrypt(data)`](#encryptdata)
    - [`crypto.hmac`](#cryptohmac)
      - [`crypto.hmac.create(hash, secret)`](#cryptohmaccreatehash-secret)
        - [`digest(data)`](#digestdata)
    - [`crypto.keys`](#cryptokeys)
    - [`crypto.keys.generateKeyPair(type, bits)`](#cryptokeysgenerateKeyPairtype-bits)
    - [`crypto.keys.generateEphemeralKeyPair(curve)`](#cryptokeysgenerateEphemeralKeyPaircurve)
    - [`crypto.keys.keyStretcher(cipherType, hashType, secret)`](#cryptokeyskeyStretchercipherType-hashType-secret)
    - [`crypto.keys.marshalPublicKey(key, [type])`](#cryptokeysmarshalPublicKeykey-type)
    - [`crypto.keys.unmarshalPublicKey(buf)`](#cryptokeysunmarshalPublicKeybuf)
    - [`crypto.keys.marshalPrivateKey(key, [type])`](#cryptokeysmarshalPrivateKeykey-type)
    - [`crypto.keys.unmarshalPrivateKey(buf)`](#cryptokeysunmarshalPrivateKeybuf)
    - [`crypto.keys.import(pem, password)`](#cryptokeysimportpem-password)
    - [`crypto.randomBytes(number)`](#cryptorandomBytesnumber)
    - [`crypto.pbkdf2(password, salt, iterations, keySize, hash)`](#cryptopbkdf2password-salt-iterations-keySize-hash)
  - [Contribute](#Contribute)
  - [License](#License)

## Install

```sh
npm install --save libp2p-crypto
```

## Usage

```js
const crypto = require('libp2p-crypto')

// Now available to you:
//
// crypto.aes
// crypto.hmac
// crypto.keys
// etc.
//
// See full API details below...
```

### Web Crypto API

The `libp2p-crypto` library depends on the [Web Crypto API](https://developer.mozilla.org/en-US/docs/Web/API/Web_Crypto_API) in the browser. Web Crypto is available in all modern browsers, however browsers restrict its usage to [Secure Contexts](https://developer.mozilla.org/en-US/docs/Web/Security/Secure_Contexts).

**This means you will not be able to use some `libp2p-crypto` functions in the browser when the page is served over HTTP.** To enable the Web Crypto API and allow `libp2p-crypto` to work fully, please serve your page over HTTPS.

## API

### `crypto.aes`

Exposes an interface to AES encryption (formerly Rijndael), as defined in U.S. Federal Information Processing Standards Publication 197.

This uses `CTR` mode.

#### `crypto.aes.create(key, iv)`

- `key: Buffer` The key, if length `16` then `AES 128` is used. For length `32`, `AES 256` is used.
- `iv: Buffer` Must have length `16`.

Returns `Promise<{decrypt<Function>, encrypt<Function>}>`

##### `decrypt(data)`

- `data: Buffer`

Returns `Promise<Buffer>`

##### `encrypt(data)`

- `data: Buffer`

Returns `Promise<Buffer>`

```js
const crypto = require('libp2p-crypto')

// Setting up Key and IV

// A 16 bytes array, 128 Bits, AES-128 is chosen
const key128 = Buffer.from([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15])

// A 16 bytes array, 128 Bits,
const IV = Buffer.from([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15])

async function main () {
  const decryptedMessage = 'Hello, world!'

  // Encrypting
  const cipher = await crypto.aes.create(key128, IV)
  const encryptedBuffer = await cipher.encrypt(Buffer.from(decryptedMessage))
  console.log(encryptedBuffer)
  // prints: <Buffer 42 f1 67 d9 2e 42 d0 32 9e b1 f8 3c>

  // Decrypting
  const decipher = await crypto.aes.create(key128, IV)
  const decryptedBuffer = await cipher.decrypt(encryptedBuffer)

  console.log(decryptedBuffer)
  // prints: <Buffer 42 f1 67 d9 2e 42 d0 32 9e b1 f8 3c>

  console.log(decryptedBuffer.toString('utf-8'))
  // prints: Hello, world!
}

main()
```

### `crypto.hmac`

Exposes an interface to the Keyed-Hash Message Authentication Code (HMAC) as defined in U.S. Federal Information Processing Standards Publication 198. An HMAC is a cryptographic hash that uses a key to sign a message. The receiver verifies the hash by recomputing it using the same key.

#### `crypto.hmac.create(hash, secret)`

- `hash: String`
- `secret: Buffer`

Returns `Promise<{digest<Function>}>`

##### `digest(data)`

- `data: Buffer`

Returns `Promise<Buffer>`

Example:

```js
const crypto = require('libp2p-crypto')

async function main () {
  const hash = 'SHA1' // 'SHA256' || 'SHA512'
  const hmac = await crypto.hmac.create(hash, Buffer.from('secret'))
  const sig = await hmac.digest(Buffer.from('hello world'))
  console.log(sig)
}

main()
```

### `crypto.keys`

**Supported Key Types**

The [`generateKeyPair`](#generatekeypairtype-bits), [`marshalPublicKey`](#marshalpublickeykey-type), and [`marshalPrivateKey`](#marshalprivatekeykey-type) functions accept a string `type` argument.

Currently the `'RSA'` and `'ed25519'` types are supported, although ed25519 keys support only signing and verification of messages.  For encryption / decryption support, RSA keys should be used.

Installing the [libp2p-crypto-secp256k1](https://github.com/libp2p/js-libp2p-crypto-secp256k1) module adds support for the `'secp256k1'` type, which supports ECDSA signatures using the secp256k1 elliptic curve popularized by Bitcoin.  This module is not installed by default, and should be explicitly depended on if your project requires secp256k1 support.

### `crypto.keys.generateKeyPair(type, bits)`

- `type: String`, see [Supported Key Types](#supported-key-types) above.
- `bits: Number` Minimum of 1024

Returns `Promise<{privateKey<Buffer>, publicKey<Buffer>}>`

Generates a keypair of the given type and bitsize.

### `crypto.keys.generateEphemeralKeyPair(curve)`

- `curve: String`, one of `'P-256'`, `'P-384'`, `'P-521'` is currently supported

Returns `Promise`

Generates an ephemeral public key and returns a function that will compute the shared secret key.

Focuses only on ECDH now, but can be made more general in the future.

Resolves to an object of the form:

```js
{
  key: Buffer,
  genSharedKey: Function
}
```

### `crypto.keys.keyStretcher(cipherType, hashType, secret)`

- `cipherType: String`, one of `'AES-128'`, `'AES-256'`, `'Blowfish'`
- `hashType: String`, one of `'SHA1'`, `SHA256`, `SHA512`
- `secret: Buffer`

Returns `Promise`

Generates a set of keys for each party by stretching the shared key.

Resolves to an object of the form:

```js
{
  k1: {
    iv: Buffer,
    cipherKey: Buffer,
    macKey: Buffer
  },
  k2: {
    iv: Buffer,
    cipherKey: Buffer,
    macKey: Buffer
  }
}
```

### `crypto.keys.marshalPublicKey(key, [type])`

- `key: keys.rsa.RsaPublicKey | keys.ed25519.Ed25519PublicKey | require('libp2p-crypto-secp256k1').Secp256k1PublicKey`
- `type: String`, see [Supported Key Types](#supported-key-types) above.  Defaults to 'rsa'.

Returns `Buffer`

Converts a public key object into a protobuf serialized public key.

### `crypto.keys.unmarshalPublicKey(buf)`

- `buf: Buffer`

Returns `RsaPublicKey|Ed25519PublicKey|Secp256k1PublicKey`

Converts a protobuf serialized public key into its representative object.

### `crypto.keys.marshalPrivateKey(key, [type])`

- `key: keys.rsa.RsaPrivateKey | keys.ed25519.Ed25519PrivateKey | require('libp2p-crypto-secp256k1').Secp256k1PrivateKey`
- `type: String`, see [Supported Key Types](#supported-key-types) above.

Returns `Buffer`

Converts a private key object into a protobuf serialized private key.

### `crypto.keys.unmarshalPrivateKey(buf)`

- `buf: Buffer`

Returns `Promise<RsaPrivateKey|Ed25519PrivateKey|Secp256k1PrivateKey>`

Converts a protobuf serialized private key into its representative object.

### `crypto.keys.import(pem, password)`

- `pem: string`
- `password: string`

Returns `Promise<RsaPrivateKey>`

Converts a PEM password protected private key into its representative object.

### `crypto.randomBytes(number)`

- `number: Number`

Returns `Buffer`

Generates a Buffer with length `number` populated by random bytes.

### `crypto.pbkdf2(password, salt, iterations, keySize, hash)`

- `password: String`
- `salt: String`
- `iterations: Number`
- `keySize: Number` in bytes
- `hash: String` the hashing algorithm ('sha1', 'sha2-512', ...)

Computes the Password Based Key Derivation Function 2; returning a new password.

## Contribute

Feel free to join in. All welcome. Open an [issue](https://github.com/libp2p/js-libp2p-crypto/issues)!

This repository falls under the IPFS [Code of Conduct](https://github.com/ipfs/community/blob/master/code-of-conduct.md).

[![](https://cdn.rawgit.com/jbenet/contribute-ipfs-gif/master/img/contribute.gif)](https://github.com/ipfs/community/blob/master/contributing.md)

## License

[MIT](./LICENSE)