Ruby implementation of HD Structure of SLIP-0013 Authentication using deterministic hierarchy

slip13.rb

# lib/slip13.rb

# Ruby implementation of SLIP-0013 : Authentication using deterministic hierarchy
# https://doc.satoshilabs.com/slips/slip-0013.html

module SLIP13
  class HDNode
    def initialize(uri, index = 0)
      @uri = uri
      @index = index
    end

    def self.derive(uri, index = 0)
      new(uri, index).derive
    end

    def derive
      "m/#{hardened_paths.join("/")}"
    end

  private

    def hardened_paths
      unhardened_paths.map do |path|
        0x80000000 | path
      end
    end

    def unhardened_paths
      [purpose] + digest.unpack('I8')[0..3]
    end

    def purpose
      13
    end

    def digest
      sha256 = Digest::SHA256.new
      sha256 << [@index].pack('V')
      sha256 << @uri
      sha256.digest
    end
  end
end


# spec/lib/slip13_spec.rb

require 'spec_helper'
require_relative '../../lib/slip13'

describe SLIP13::HDNode do
  context ".derive" do
    it "Derives HD nodes according to SLIP13" do
      test_vectors = [
        {
          index: 0,
          uri: "https://satoshi@bitcoin.org/login",
          path: "m/2147483661/2637750992/2845082444/3761103859/4005495825"
        },
        {
          index: 3,
          uri: "ftp://satoshi@bitcoin.org:2323/pub",
          path: "m/2147483661/3098912377/2734671409/3632509519/3125730426"
        },
        {
          index: 47,
          uri: "ssh://satoshi@bitcoin.org",
          path: "m/2147483661/4111640159/2980290904/2332131323/3701645358"
        },
        {
          index: 0,
          uri: "https://www.mrcoin.eu/callback/bitid",
          path: "m/2147483661/2771203381/2356980894/2767891142/3030839793"
        },
        {
          index: 1,
          uri: "https://www.mrcoin.eu/callback/bitid",
          path: "m/2147483661/3666892818/2293082814/2553532930/2457674449"
        }
      ]

      test_vectors.each do |test_vector|
        expect(
          SLIP13::HDNode.derive(test_vector[:uri], test_vector[:index])
        ).to eq(test_vector[:path])
      end
    end
  end
end