eth/chains: implement eip 155 for replay protection (#20)

* eth/chains: implement eip 155 for replay protection

* spec: test for legacy (pre 155) v values

* eth/chains: fix yard docs

lib/eth.rb

@@ -17,7 +17,8 @@ module Eth
 end
 
 # Loads the `Eth` module classes.
-require 'eth/key'
 require 'eth/address'
+require 'eth/chains'
+require 'eth/key'
 require 'eth/utils'
 require 'eth/version'

lib/eth/chains.rb

@@ -0,0 +1,120 @@
+# Copyright (c) 2016-2022 The Ruby-Eth Contributors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Provides the `Eth` module.
+module Eth
+
+  # Encapsulates `Chains` IDs and utilities for EIP-155 compatibility.
+  # ref: https://eips.ethereum.org/EIPS/eip-155
+  module Chains
+    extend self
+
+    # Chain ID for Ethereum mainnet
+    ETHEREUM = 1
+
+    # Chain ID for Expanse mainnet
+    EXPANSE = 2
+
+    # Chain ID for Optimistic Ethereum mainnet
+    OPTIMISM = 10
+
+    # Chain ID for Ethereum Classic mainnet
+    CLASSIC = 61
+
+    # Chain ID for POA Network mainnet
+    POA_NET = 99
+
+    # Chain ID for xDAI mainnet
+    XDAI = 100
+
+    # Chain ID for Arbitrum mainnet
+    ARBITRUM = 42161
+
+    # Chain ID for Morden (Ethereum) testnet
+    MORDEN = 2
+
+    # Chain ID for Ropsten testnet
+    ROPSTEN = 3
+
+    # Chain ID for Rinkeby testnet
+    RINKEBY = 4
+
+    # Chain ID for Goerli testnet
+    GOERLI = 5
+
+    # Chain ID for Kotti testnet
+    KOTTI = 6
+
+    # Chain ID for Kovan testnet
+    KOVAN = 42
+
+    # Chain ID for Morden (Classic) testnet
+    MORDEN_CLASSIC = 62
+
+    # Chain ID for Mordor testnet
+    MORDOR = 63
+
+    # Chain ID for Optimistik Kovan testnet
+    KOVAN_OPTIMISM = 69
+
+    # Chain ID for Arbitrum xDAI testnet
+    XDAI_ARBITRUM = 200
+
+    # Chain ID for Optimistic Goerli testnet
+    GOERLI_OPTIMISM = 420
+
+    # Chain ID for Arbitrum Rinkeby testnet
+    RINKEBY_ARBITRUM = 421611
+
+    # Chain ID for the geth private network preset
+    PRIVATE_GETH = 1337
+
+    # Indicates wether the given `v` indicates a legacy chain value
+    # without EIP-155 replay protection.
+    #
+    # @param v [Integer] the signature's `v` value
+    # @return [Boolean] true if legacy value
+    def is_legacy? v
+      [27, 28].include? v
+    end
+
+    # Convert a given `v` value to an ECDSA recovery id for the given
+    # EIP-155 chain ID.
+    #
+    # @param v [Integer] the signature's `v` value
+    # @param chain [Integer] the chain id the signature was generated on.
+    # @return [Integer] the recovery id corresponding to `v`.
+    # @raise [ArgumentError] if the given `v` is invalid.
+    def to_recov v, chain = ETHEREUM
+      x = 0 + 2 * chain + 35
+      y = 1 + 2 * chain + 35
+      if  is_legacy? v
+        return v - 27
+      elsif [x, y].include? v
+        return v - 35 - 2 * chain
+      else
+        raise ArgumentError, "Invalid v value for chain #{chain}. Invalid chain ID?"
+      end
+    end
+
+    # Converts a recovery ID into the expected `v` on a given chain.
+    #
+    # @param recov [Integer] signature recovery id.
+    # @param chain [Integer] the chain id the signature was generated on.
+    # @return [Integer] the signature's `v` value.
+    def to_v recov, chain = ETHEREUM
+      v = 2 * chain + 35 + recov
+    end
+  end
+end

spec/eth/chains_spec.rb

@@ -0,0 +1,82 @@
+require 'spec_helper'
+
+describe Eth::Chains do
+  describe "#CHAIN_ID" do
+    it "has EIP155 chain ids for mainnets, testnets, and devnets" do
+      # Chain IDs for selected mainnets
+      expect(Eth::Chains::ETHEREUM).to eq 1
+      expect(Eth::Chains::EXPANSE).to eq 2
+      expect(Eth::Chains::OPTIMISM).to eq 10
+      expect(Eth::Chains::CLASSIC).to eq 61
+      expect(Eth::Chains::POA_NET).to eq 99
+      expect(Eth::Chains::XDAI).to eq 100
+      expect(Eth::Chains::ARBITRUM).to eq 42161
+
+      # Chain IDs for selected testnets
+      expect(Eth::Chains::MORDEN).to eq 2
+      expect(Eth::Chains::ROPSTEN).to eq 3
+      expect(Eth::Chains::RINKEBY).to eq 4
+      expect(Eth::Chains::GOERLI).to eq 5
+      expect(Eth::Chains::KOTTI).to eq 6
+      expect(Eth::Chains::KOVAN).to eq 42
+      expect(Eth::Chains::MORDEN_CLASSIC).to eq 62
+      expect(Eth::Chains::MORDOR).to eq 63
+      expect(Eth::Chains::KOVAN_OPTIMISM).to eq 69
+      expect(Eth::Chains::XDAI_ARBITRUM).to eq 200
+      expect(Eth::Chains::GOERLI_OPTIMISM).to eq 420
+      expect(Eth::Chains::RINKEBY_ARBITRUM).to eq 421611
+
+      # Chain IDs for selected private networks
+      expect(Eth::Chains::PRIVATE_GETH).to eq 1337
+    end
+  end
+
+  describe ".is_legacy" do
+    it "can detect legacy values for v" do
+      expect(Eth::Chains.is_legacy? 0).not_to be_truthy
+      expect(Eth::Chains.is_legacy? 1).not_to be_truthy
+      expect(Eth::Chains.is_legacy? 27).to be_truthy
+      expect(Eth::Chains.is_legacy? 28).to be_truthy
+      expect(Eth::Chains.is_legacy? 37).not_to be_truthy
+      expect(Eth::Chains.is_legacy? 38).not_to be_truthy
+    end
+  end
+
+  describe ".to_v .to_recovery_id" do
+    it "can convert ethereum recovery ids to v" do
+      expect(Eth::Chains.to_v 0).to be 37
+      expect(Eth::Chains.to_v 1).to be 38
+    end
+    it "can convert other chain's recovery ids to v" do
+      expect(Eth::Chains.to_v 0, Eth::Chains::CLASSIC).to be 157
+      expect(Eth::Chains.to_v 1, Eth::Chains::XDAI).to be 236
+      expect(Eth::Chains.to_v 0, Eth::Chains::ARBITRUM).to be 84357
+      expect(Eth::Chains.to_v 1, Eth::Chains::MORDEN_CLASSIC).to be 160
+      expect(Eth::Chains.to_v 0, Eth::Chains::GOERLI_OPTIMISM).to be 875
+      expect(Eth::Chains.to_v 1, Eth::Chains::RINKEBY_ARBITRUM).to be 843258
+      expect(Eth::Chains.to_v 0, Eth::Chains::PRIVATE_GETH).to be 2709
+    end
+    it "can recover v from ethereum recovery id" do
+      expect(Eth::Chains.to_recov 37).to be 0
+      expect(Eth::Chains.to_recov 38).to be 1
+
+      # legacy v
+      expect(Eth::Chains.to_recov 27).to be 0
+      expect(Eth::Chains.to_recov 28).to be 1
+    end
+    it "can recover v from other chain's recovery id" do
+      expect(Eth::Chains.to_recov 157, Eth::Chains::CLASSIC).to be 0
+      expect(Eth::Chains.to_recov 236, Eth::Chains::XDAI).to be 1
+      expect(Eth::Chains.to_recov 84357, Eth::Chains::ARBITRUM).to be 0
+      expect(Eth::Chains.to_recov 160, Eth::Chains::MORDEN_CLASSIC).to be 1
+      expect(Eth::Chains.to_recov 875, Eth::Chains::GOERLI_OPTIMISM).to be 0
+      expect(Eth::Chains.to_recov 843258, Eth::Chains::RINKEBY_ARBITRUM).to be 1
+      expect(Eth::Chains.to_recov 2709, Eth::Chains::PRIVATE_GETH).to be 0
+    end
+    it "raises an error for invalid v on chain ids" do
+      expect {Eth::Chains.to_recov 0}.to raise_error ArgumentError
+      expect {Eth::Chains.to_recov 36}.to raise_error ArgumentError
+      expect {Eth::Chains.to_recov 843258, Eth::Chains::PRIVATE_GETH}.to raise_error ArgumentError
+    end
+  end
+end