Crypto primitives for libp2p


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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.

Lead Maintainer

Jacob Heun

Table of Contents


npm install --save libp2p-crypto


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-cryptolibrary depends on the Web Crypto APIin the browser. Web Crypto is available in all modern browsers, however browsers restrict its usage to Secure Contexts.

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



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

This uses CTRmode.

crypto.aes.create(key, iv)

  • key: BufferThe key, if length 16then AES 128is used. For length 32, AES 256is used.
  • iv: BufferMust have length 16.

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

  • data: Buffer

Returns Promise<Buffer>

  • data: Buffer

Returns Promise<Buffer>

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))
  // 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)

  // prints: <Buffer 42 f1 67 d9 2e 42 d0 32 9e b1 f8 3c>

  // prints: Hello, world!



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>}>

  • data: Buffer

Returns Promise<Buffer>


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'))



Supported Key Types

The generateKeyPair, marshalPublicKey, and marshalPrivateKeyfunctions accept a string typeargument.

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-secp256k1module 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)

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

Generates a keypair of the given type and bitsize.


  • 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:

  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:

  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 Typesabove. Defaults to 'rsa'.

Returns Buffer

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


  • 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 Typesabove.

Returns Buffer

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


  • 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.


  • number: Number

Returns Buffer

Generates a Buffer with length numberpopulated by random bytes.

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

  • password: String
  • salt: String
  • iterations: Number
  • keySize: Numberin bytes
  • hash: Stringthe hashing algorithm ('sha1', 'sha2-512', ...)

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


Feel free to join in. All welcome. Open an issue!

This repository falls under the IPFS Code of Conduct.






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