Use bitcoinjs-lib for bitcoin address generation

See: oleganza/btcruby#32

Gemfile.lock

@@ -430,4 +430,4 @@ DEPENDENCIES
   webmock
 
 BUNDLED WITH
-   1.16.1
+   1.16.2

app/lib/btc/address_generator.rb

@@ -24,11 +24,18 @@ def address(idx)
     private
 
     def multisig_address(idx)
-      keychain_group = BTC::KeychainGroup.new(extended_keys: xpub)
-      keychain_group.standard_address({
-        index: idx,
-        signatures_required: signatures_required,
-      })
+      keychains = xpub.map { |x| BTC::Keychain.new(extended_key: x) }
+      keys = keychains.map { |keychain| keychain.derived_key(idx) }
+      public_keys = keys.map { |key| BTC.to_hex(key.public_key) }.sort
+
+      command = [
+        "node",
+        Rails.root.join("lib", "address_gen.js"),
+        public_keys.join(","),
+        signatures_required,
+      ].join(" ")
+      stdout_str, stderr_str, status = Open3.capture3(command)
+      stdout_str.chomp
     end
 
     def single_address(idx)

docs/bitcoin.md

@@ -7,3 +7,13 @@ Bitcoin addresses will be generated from the supplied `BTC_MASTER_PUBLIC_KEY`.
 ## Bitcoind setup
 
 - Set `txindex=1` to [index all transactions](https://bitcore.io/guides/full-node/).
+
+## Tips
+
+If you will be using a wallet like Electrum to manage the funds, the master public key you find there *is not* the one you should place here. The key placed here can be derived the following manner:
+
+```sh
+ruby scripts/electrum.rb master_public_key_you_see_in_electrum
+```
+
+Of course, test that the addresses generated by this application are the same as the receiving addresses in Electrum.

lib/address_gen.js

@@ -0,0 +1,10 @@
+let bitcoin = require('bitcoinjs-lib')
+
+let pubKeys = process.argv[2].split(",").sort().map(function (hex) { return Buffer.from(hex, 'hex') })
+let signaturesRequired = parseInt(process.argv[3])
+
+var redeemScript = bitcoin.script.multisig.output.encode(signaturesRequired, pubKeys)
+var scriptPubKey = bitcoin.script.scriptHash.output.encode(bitcoin.crypto.hash160(redeemScript))
+var address = bitcoin.address.fromOutputScript(scriptPubKey)
+
+console.log(address)

package.json

@@ -1,5 +1,7 @@
 {
   "name": "crypto_cold_store",
   "private": true,
-  "dependencies": {}
+  "dependencies": {
+    "bitcoinjs-lib": "^3.3.2"
+  }
 }

scripts/electrum.rb

@@ -0,0 +1,8 @@
+require "btcruby"
+
+def receiving_mpk_for(parent_mpk)
+  keychain = BTC::Keychain.new(extended_key: parent_mpk)
+  keychain.derived_keychain("0").xpub
+end
+
+puts receiving_mpk_for(ARGV[0])

spec/lib/btc/address_generator_spec.rb

@@ -76,20 +76,25 @@ module Btc
       end
 
       context "multiple extended keys" do
-        let(:generator) do
-          described_class.new(xpub: xpub, signatures_required: 2)
-        end
         let(:xpub) do
-          [
-            "xpub6DY7Fqdz98GSsFDN96Levia3PwnREqhFER5RtKwiwrDzBJpEtGX5VcZdPrLgJriUfStunLmWYxrHM6XPygEJhrXZGrVh1fVZc2AQkAVPf9n",
-            "xpub6DfZs3n92pxJ3LCBf7bfgbyrECteT8PWmee5UpZhG1aBurdF5t1Tu2jxdnCBXETztHu6YkJ8Hin8t8qwPsh3YScNX3dLxduNSaevLF3KLpq",
-            "xpub6FFgmnaotx9GP3XkdK8oS8j3ExWBXXGdJ5LeWYmCHUAppaG85HPm4QRGrtowZJfwzDqjKkp1kc5mzUwa2W1PEicuynzC45myaa4vVG7bNJy",
+          # These are from Electrum
+          mpks = [
+            "xpub6D4K8Hb6sMZwwtbk6p94RnRewTb6PykJc1zZwB3GUozGSNXLnTdL2T8uXRehiD9d5Dis3bDpJCvR3pFZcYUu2xpPj5Z73oFNUUQKwkFTewo",
+            "xpub661MyMwAqRbcGHY2QrfyiUyvSv93zCQN8Cv3eXFB3ivnq7SQ6TLUJueJnGZKR8r8CQ5cLsGrr9D71uwAW9RLKqFyUybARtbbqg1kiHopBsZ",
           ]
+          # but since we want the xpub of the receiving chain and not change
+          # chain...
+          mpks.map do |mpk|
+            BTC::Keychain.new(extended_key: mpk).derived_keychain("0").xpub
+          end
+        end
+        let(:generator) do
+          described_class.new(xpub: xpub, signatures_required: 1)
         end
 
         it "generates an address at the given index for the required number of signatures" do
-          expect(generator.address(0)).to eq "397Zemr1wRy3hznQBsdQeeu1d8U5M1HrTZ"
-          expect(generator.address(18)).to eq "3GAGdkU6awG9aiDyiyrmrjvo8tpHbab5Ff"
+          expect(generator.address(0)).to eq "3GbE5Hn5NNfAbkk33AquoZqtoehkDDBEZn"
+          expect(generator.address(18)).to eq "3CwgJ7iYBWufLpwgsGKikjEH5YL38CAfz3"
         end
       end
     end

spec/services/btc/addresses/creation/gen_address_spec.rb

@@ -6,21 +6,26 @@ module Creation
       RSpec.describe GenAddress do
 
         let(:master_public_key) do
-          [
-            "xpub6DY7Fqdz98GSsFDN96Levia3PwnREqhFER5RtKwiwrDzBJpEtGX5VcZdPrLgJriUfStunLmWYxrHM6XPygEJhrXZGrVh1fVZc2AQkAVPf9n",
-            "xpub6DfZs3n92pxJ3LCBf7bfgbyrECteT8PWmee5UpZhG1aBurdF5t1Tu2jxdnCBXETztHu6YkJ8Hin8t8qwPsh3YScNX3dLxduNSaevLF3KLpq",
-            "xpub6FFgmnaotx9GP3XkdK8oS8j3ExWBXXGdJ5LeWYmCHUAppaG85HPm4QRGrtowZJfwzDqjKkp1kc5mzUwa2W1PEicuynzC45myaa4vVG7bNJy",
+          # These are from Electrum
+          # chain...
+          mpks = [
+            "xpub6D4K8Hb6sMZwwtbk6p94RnRewTb6PykJc1zZwB3GUozGSNXLnTdL2T8uXRehiD9d5Dis3bDpJCvR3pFZcYUu2xpPj5Z73oFNUUQKwkFTewo",
+            "xpub661MyMwAqRbcGHY2QrfyiUyvSv93zCQN8Cv3eXFB3ivnq7SQ6TLUJueJnGZKR8r8CQ5cLsGrr9D71uwAW9RLKqFyUybARtbbqg1kiHopBsZ",
           ]
+          # but since we want the xpub of the receiving chain...
+          mpks.map do |mpk|
+            BTC::Keychain.new(extended_key: mpk).derived_keychain("0").xpub
+          end
         end
-        let(:address_18) { "3GAGdkU6awG9aiDyiyrmrjvo8tpHbab5Ff" }
+        let(:address_1) { "3Dur7FTopK9jAUNSmLyGggMQc1nsnL2Cv6" }
 
         it "generates an address based on the keychain[address_index]" do
           resulting_ctx = described_class.execute(
             master_public_key: master_public_key,
-            signatures_required: 2,
-            address_index: 18,
+            signatures_required: 1,
+            address_index: 1,
           )
-          expect(resulting_ctx.public_address).to eq address_18
+          expect(resulting_ctx.public_address).to eq address_1
         end
 
       end