bip-schnorrrb Build Status Gem Version MIT License

This is a Ruby implementation of the Schnorr signature scheme over the elliptic curve. This implementation relies on the ecdsa gem for operate elliptic curves.

The code is based upon the BIP340.

Installation

Add this line to your application's Gemfile:

gem 'bip-schnorr', require: 'schnorr'

And then execute:

$ bundle

Or install it yourself as:

$ gem install bip-schnorr

Usage

Signing

require 'schnorr'

private_key = ['B7E151628AED2A6ABF7158809CF4F3C762E7160F38B4DA56A784D9045190CFEF'].pack("H*")

message = ['5E2D58D8B3BCDF1ABADEC7829054F90DDA9805AAB56C77333024B9D0A508B75C'].pack('H*')

# create signature
signature = Schnorr.sign(message, private_key)
# if use auxiliary random data, specify it to the 3rd arguments.
aux_rand = SecureRandom.bytes(32) # aux_rand must be a 32-byte binary.
signature = Schnorr.sign(message, private_key, aux_rand)

# signature r value
signature.r 

# signature s value
signature.s 

# convert signature to binary

signature.encode

Verification

require 'schnorr'

# public key does not start with 02 or 03.
public_key = ['DFF1D77F2A671C5F36183726DB2341BE58FEAE1DA2DECED843240F7B502BA659'].pack('H*')

signature = ['6896BD60EEAE296DB48A229FF71DFE071BDE413E6D43F917DC8DCF8C78DE33418906D11AC976ABCCB20B091292BFF4EA897EFCB639EA871CFA95F6DE339E4B0A'].pack('H*')

message = ['243F6A8885A308D313198A2E03707344A4093822299F31D0082EFA98EC4E6C89'].pack('H*')

# verify signature.(result is true or false)
result = Schnorr.valid_sig?(message, public_key, signature) 

# signature convert to Signature object
sig = Schnorr::Signature.decode(signature)

Note

This library changes the following functions of ecdsa gem in lib/schnorr/ec_point_ext.rb.

  • ECDSA::Point class has following two instance methods.
    • #has_even_y? check the y-coordinate of this point is an even.
    • #encode(only_x = false) encode this point into a binary string.
  • ECDSA::Format::PointOctetString#decode supports decoding only from x coordinate.