SYNOPSIS

This module provides native bindings to ecdsa secp256k1 functions.
This library is experimental, so use at your own risk.

INSTALL

If you have gmp installed secp256k1 will use it. Otherwise it should fallback to openssl.

• arch pacman -S gmp
• ubuntu sudo apt-get install libgmp-dev

from npm

npm install secp256k1

from git

git clone git@github.com:wanderer/secp256k1-node.git
cd secp256k1-node
git submodule init
git submodule update
npm install

USAGE

var ecdsa = require('secp256k1')
var crypto = require('crypto')

var privateKey = crypto.randomBytes(32)
//a random message to sign
var msg = crypto.randomBytes(32)

//get the public key in a compressed format
var pubKey = ecdsa.createPublicKey(privateKey, true)

//sign the message
var sig = ecdsa.sign(msg, privateKey)

//verify the signature
if(ecdsa.verify(msg, sig, pubKey)){
  console.log("valid signature")
}

TEST

run npm test API

Signature All functions that take signatures can take two formats

• DER - which should be a repersented as an Buffer
• Compact - which should be an Object with the following
  • signature - a Buffer
  • recovery - an Integer for the recovery id

secp256k1.verifySecretKey(secretKey)

Verify an ECDSA secret key.

Parameters

• secretKey - Buffer, the secret Key to verify

Returns: Boolean, true if secret key is valid, false secret key is invalid

secp256k1.verifyPublicKey(publicKey)

Verify an ECDSA public key.

Parameters

• publicKey - Buffer, the public Key to verify

Returns: Boolean, true if public key is valid, false secret key is invalid

secp256k1.sign(msg, secretkey, [DER], [cb])

Create an ECDSA signature.

Parameters

• msg - Buffer, a 32-byte message hash being signed
• secretkey - Buffer, a 32-byte secret key (assumed to be valid)
• DER - Boolean, Optional if true the signature produced will be in DER format. Defaults to false
• cb - function, Optional the callback. The callback is given the signature. If no callback is given the function will run sync.

Returns:

• if DER a Buffer, if no callback is given a 72-byte signature is returned
• else an compact siganture Object

secp256k1.verify(mgs, sig, pubKey, [cb])

Verify an ECDSA signature. Runs asynchronously if given a callback

Parameters

• mgs - Buffer, the 32-byte message hash being verified
• sig - Buffer, the signature being verified
• pubKey - Buffer, the public key
• cb - a callback if you want to run async

Returns: Integer,

• true correct signature
• false incorrect signature

secp256k1.recover(msg, sig, compressed, [cb])

Recover an ECDSA public key from a compact signature in the process also verifing it. Runs asynchronously if given a callback

Parameters

• msg - Buffer, the message assumed to be signed
• sig - Buffer, the signature
• compressed - Boolean, whether to recover a compressed or uncompressed pubkey. Defaults to true
• cb - function, Recover an ECDSA public key from a compact signature. In the process also verifing it.

Returns: Buffer, the pubkey, a 33 or 65 byte buffer

secp256k1.createPublicKey(secKey, compressed)

Compute the public key for a secret key.

Parameters

• secKey - Buffer, a 32-byte private key.
• compressed - Boolean, whether the computed public key should be compressed

Returns: Buffer, a 33-byte (if compressed) or 65-byte (if uncompressed).

secp256k1.exportPrivateKey(secretKey, compressed)

Parameters

• secretKey - Buffer
• compressed - Boolean

** Returns**: Buffer, privateKey

secp256k1.importPrivateKey(privateKey)

Parameters

• privateKey - Buffer

Returns: Buffer, secretKey

secp256k1.decompressPublickey(secretKey)

Parameters

• secretKey - Buffer

Returns: Buffer, This module provides native bindings to ecdsa secp256k1 functions

secp256k1.privKeyTweakAdd(secretKey)

Parameters

• privateKey - Buffer
• tweak - Buffer

Returns: Buffer

secp256k1.privKeyTweakMul(privateKey, tweak)

Parameters

• privateKey - Buffer
• tweak - Buffer

Returns: Buffer

LICENSE

MIT