Add Bitcoin::SilentPayment::Addr

lib/bitcoin/silent_payment.rb

@@ -0,0 +1,5 @@
+module Bitcoin
+  module SilentPayment
+    autoload :Addr, 'bitcoin/sp/addr'
+  end
+end

lib/bitcoin/sp/addr.rb

@@ -0,0 +1,55 @@
+module Bitcoin
+  module SilentPayment
+    class Addr
+
+      HRP_MAINNET = 'sp'
+      HRP_TESTNET = 'tsp'
+      MAX_CHARACTERS = 1023
+
+      attr_reader :version
+      attr_reader :scan_key
+      attr_reader :spend_key
+
+      # Constructor.
+      # @param [Bitcoin::Key] scan_key
+      # @param [Bitcoin::Key] spend_key
+      def initialize(version, scan_key:, spend_key:)
+        raise ArgumentError, "version must be integer." unless version.is_a?(Integer)
+        raise ArgumentError, "scan_key must be Bitcoin::Key." unless scan_key.is_a?(Bitcoin::Key)
+        raise ArgumentError, "spend_key must be Bitcoin::Key." unless spend_key.is_a?(Bitcoin::Key)
+        raise ArgumentError, "version '#{version}' is unsupported." unless version.zero?
+
+        @version = version
+        @scan_key = scan_key
+        @spend_key = spend_key
+      end
+
+      # Parse silent payment address.
+      # @param [String] A silent payment address.
+      # @return [Bitcoin::SilentPayment::Addr]
+      def self.from_string(addr)
+        raise ArgumentError, "addr must be string." unless addr.is_a?(String)
+        hrp, data, spec = Bech32.decode(addr, MAX_CHARACTERS)
+        unless hrp == Bitcoin.chain_params.mainnet? ? HRP_MAINNET : HRP_TESTNET
+          raise ArgumentError, "The specified hrp is different from the current network HRP."
+        end
+        raise ArgumentError, "spec must be bech32m." unless spec == Bech32::Encoding::BECH32M
+
+        ver = data[0]
+        payload = Bech32.convert_bits(data[1..-1], 5, 8, false).pack("C*")
+        scan_key = Bitcoin::Key.new(pubkey: payload[0...33].bth, key_type: Bitcoin::Key::TYPES[:compressed])
+        spend_key = Bitcoin::Key.new(pubkey: payload[33..-1].bth, key_type: Bitcoin::Key::TYPES[:compressed])
+        Addr.new(ver, scan_key: scan_key, spend_key: spend_key)
+      end
+
+      # Get silent payment address.
+      # @return [String]
+      def to_s
+        hrp = Bitcoin.chain_params.mainnet? ? HRP_MAINNET : HRP_TESTNET
+        payload = [scan_key.pubkey + spend_key.pubkey].pack("H*").unpack('C*')
+        Bech32.encode(hrp, [version] + Bech32.convert_bits(payload, 8, 5), Bech32::Encoding::BECH32M)
+      end
+
+    end
+  end
+end

spec/bitcoin/silent_payment_spec.rb

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+require 'spec_helper'
+
+RSpec.describe Bitcoin::SilentPayment, network: :mainnet do
+
+  describe 'BIP352 Test Vector' do
+    it do
+      vectors = fixture_file('bip352/send_and_receive_test_vectors.json')
+      vectors.each do |v|
+        v['sending'].each do |s|
+          d = s['given']
+          recipients = d['recipients'].map do |r|
+            Bitcoin::SilentPayment::Addr.from_string(r)
+          end
+          expect(recipients.map(&:to_s)).to eq(d['recipients'])
+        end
+      end
+    end
+  end
+end