Create a heirarchical deterministic multisig addresses

lib/btcruby.rb

@@ -22,6 +22,7 @@
 require_relative 'btcruby/wif.rb'
 require_relative 'btcruby/key.rb'
 require_relative 'btcruby/keychain.rb'
+require_relative 'btcruby/keychain_group.rb'
 require_relative 'btcruby/mnemonic.rb'
 require_relative 'btcruby/wire_format.rb'
 require_relative 'btcruby/hash_id.rb'

lib/btcruby/keychain_group.rb

@@ -0,0 +1,50 @@
+module BTC
+  class KeychainGroup
+
+    attr_reader :extended_keys
+
+    def initialize(extended_keys:)
+      @extended_keys = extended_keys
+    end
+
+    def multisig_script(index: nil, signatures_required:)
+      pubkeys = derived_keys(index).map(&:public_key)
+
+      BTC::Script.multisig(
+        public_keys: pubkeys,
+        signatures_required: signatures_required,
+      )
+    end
+
+    def standard_address(index:, signatures_required:)
+      multisig_script(index: index, signatures_required: signatures_required).
+        p2sh_script.standard_address(network: network).to_s
+    end
+
+    private
+
+    def network
+      networks = keychains.map(&:network).uniq
+      return networks[0] if networks.size == 1
+      fail(
+        ArgumentError,
+        "extended_keys seem to be a combination of mainnet and testnet"
+      )
+    end
+
+    def keychains
+      @keychains ||= extended_keys.map do |extended_key|
+        Keychain.new(extended_key: extended_key)
+      end
+    end
+
+    def derived_keychains(index_or_path)
+      keychains.map { |keychain| keychain.derived_keychain(index_or_path) }
+    end
+
+    def derived_keys(index_or_path)
+      derived_keychains(index_or_path).map(&:key)
+    end
+
+  end
+end

spec/keychain_group_spec.rb

@@ -0,0 +1,82 @@
+require_relative 'spec_helper'
+
+describe BTC::KeychainGroup do
+
+  describe "#multisig_script" do
+    let(:extended_private_keys) do
+      [
+        "xprvA1XSPm4ktCeuiLSD6vYeY31EPBUjE55rYhtvviSD873YZw4rvL9nz7qf57JF7aYBsbPnwnG5PtERV63H3mHoZyuKiMddWL4ZmwSzHPHSGhX",
+        "xprvA28GaehL72bWdThY1sW7dFfraTYVnxKKLXHLuUN2RbzhHCnRKLenrZYcgnCCZymErJf1zpBiaVmpEf7WtpXR1vKVKteZBcdJr7rJBLT6xG2",
+        "xprv9zodTwqJX7DHJQd6Dk7uwGNCuX1aJGoc6zD3dyaJnoFYRsBze3FG6BE2YEQdJUQ7XYPFyfD5ijLNym9BnpgCgcAorhzyfrM2cja1eG3MC3n",
+      ]
+    end
+
+    context "from extended_keys" do
+      it "generates a multisig_script based on the derived keys at the given index and number of signatures_required" do
+        keychain_group = BTC::KeychainGroup.new(extended_keys: extended_private_keys)
+
+        multisig_script_0 = keychain_group.
+          multisig_script(index: 0, signatures_required: 2)
+        multisig_address_0 = multisig_script_0.
+          p2sh_script.standard_address.to_s
+        expect(multisig_address_0).to eq "3KBxrmV2Ye3BN3NQHva3jFnrbgwfFEDLne"
+
+        multisig_script_19 = keychain_group.
+          multisig_script(index: 19, signatures_required: 2)
+        multisig_address_19 = multisig_script_19.
+          p2sh_script.standard_address.to_s
+        expect(multisig_address_19).to eq "3QMpum8wDfKNtPCe1AbXy5rSf9mfg3U8zr"
+      end
+    end
+  end
+
+  describe "#standard_address" do
+    context "given public mainnet extended_keys" do
+      let(:extended_keys) do
+        [
+          "xpub6EcFX7Ym9LUEPkggNyebw5bCiSyk3ii3iNhC63wiEuUjr9Zj5g5DnJZrhYLTmbSPCDhuH4qZ4PkKTmubR3auDJKjxdKXkxFoh8ELj698Mf8",
+          "xpub6ELav2rfdseVRrYitFU5ZkYniqhkNYThYgZruku4xQnE823t2sKdnRmrqcgVie96i9XUQvvsJcTH4nRB6xvd2o2KMaG8amhBpcJ8AoqEU6o",
+        ]
+      end
+      let(:keychain_group) do
+        BTC::KeychainGroup.new(extended_keys: extended_keys)
+      end
+
+      it "returns the multisig address at index and for the signatures_required" do
+        address_0 = keychain_group.
+          standard_address(index: 0, signatures_required: 1).to_s
+        expect(address_0).to eq "33E6C9wpDVfmBhqy3gX8dBNQXsbBEEE5gj"
+
+        address_8 = keychain_group.
+          standard_address(index: 8, signatures_required: 1).to_s
+        expect(address_8).to eq "37AW4wGcSVhY4vm4FonuziZmKDbr9ZEjLs"
+
+        address_9 = keychain_group.
+          standard_address(index: 9, signatures_required: 1).to_s
+        expect(address_9).to eq "36MY8Vbk48Uc7M5kRS9rzQ6jRRj3g2iTDV"
+      end
+    end
+
+    context "given public testnet extended_keys" do
+      let(:extended_keys) do
+        [
+          "tpubDF7aivmHsi1vjna9uiTHuXsxpa76c69s5pYRqk9cTAMVmPm8B3SQ9xYUB5Lt3wvFbLyY1GcgU1saGHc4bpDK7cyfNLHjxoh68tBRFdeWjh6",
+          "tpubDEfAYsrZ6Bd9S3Qdx6JvL7E9kCXUDZiFprPLvgMk711VturA5j2GLWK322FgWNUz2SYseJbsnuRUyosbajP22yXruyhHXnxRqcbb5QVvKvh",
+        ]
+      end
+      let(:keychain_group) do
+        BTC::KeychainGroup.new(extended_keys: extended_keys)
+      end
+
+      it "returns the multisig address at index and for the signatures_required" do
+        # NOTE: could not find another tool, like https://coinb.in/#newMultiSig
+        # to generate multisig testnet addresses. The addresses we're testing
+        # against below were generated from Btcruby
+        address_0 = keychain_group.
+          standard_address(index: 0, signatures_required: 1).to_s
+        expect(address_0).to eq "2MwvRcRjDTQW73iwcQ6p5jt8wSWvtxdp34N"
+      end
+    end
+  end
+
+end