Add function for recovering signer address for Clique

apps/indexer/lib/indexer/block/util.ex

@@ -0,0 +1,75 @@
+defmodule Indexer.Block.Util do
+  @moduledoc """
+  Helper functions for parsing block information.
+  """
+
+  @doc """
+  Calculates the signer's address by recovering the ECDSA public key.
+
+  https://en.wikipedia.org/wiki/Elliptic_Curve_Digital_Signature_Algorithm
+  """
+  def signer(block) when is_map(block) do
+    # Last 65 bytes is the signature. Multiply by two since we haven't transformed to raw bytes
+    {extra_data, signature} = String.split_at(trim_prefix(block.extra_data), -130)
+
+    block = %{block | extra_data: extra_data}
+
+    signature_hash = signature_hash(block)
+
+    recover_pub_key(signature_hash, decode(signature))
+  end
+
+  # Signature hash calculated from the block header.
+  # Needed for PoA-based chains
+  defp signature_hash(block) do
+    header_data = [
+      decode(block.parent_hash),
+      decode(block.sha3_uncles),
+      decode(block.miner),
+      decode(block.state_root),
+      decode(block.transactions_root),
+      decode(block.receipts_root),
+      decode(block.logs_bloom),
+      block.difficulty,
+      block.number,
+      block.gas_limit,
+      block.gas_used,
+      block.timestamp,
+      decode(block.extra_data),
+      decode(block.mix_hash),
+      decode(block.nonce)
+    ]
+
+    :keccakf1600.hash(:sha3_256, ExRLP.encode(header_data))
+  end
+
+  defp trim_prefix("0x" <> rest), do: rest
+
+  defp decode("0x" <> rest) do
+    decode(rest)
+  end
+
+  defp decode(data) do
+    Base.decode16!(data, case: :mixed)
+  end
+
+  # Recovers the key from the signature hash and signature
+  defp recover_pub_key(signature_hash, signature) do
+    <<
+      r::bytes-size(32),
+      s::bytes-size(32),
+      v::integer-size(8)
+    >> = signature
+
+    # First byte represents compression which can be ignored
+    # Private key is the last 64 bytes
+    {:ok, <<_compression::bytes-size(1), private_key::binary>>} =
+      :libsecp256k1.ecdsa_recover_compact(signature_hash, r <> s, :uncompressed, v)
+
+    # Public key comes from the last 20 bytes
+    <<_::bytes-size(12), public_key::binary>> = :keccakf1600.hash(:sha3_256, private_key)
+
+    miner_address = Base.encode16(public_key, case: :lower)
+    "0x" <> miner_address
+  end
+end

apps/indexer/mix.exs

@@ -46,10 +46,14 @@ defmodule Indexer.MixProject do
     [
       # JSONRPC access to Parity for `Explorer.Indexer`
       {:ethereum_jsonrpc, in_umbrella: true},
+      # RLP encoding
+      {:ex_rlp, "~> 0.3"},
       # Code coverage
       {:excoveralls, "~> 0.10.0", only: [:test], github: "KronicDeth/excoveralls", branch: "circle-workflows"},
       # Importing to database
       {:explorer, in_umbrella: true},
+      # libsecp2561k1 crypto functions
+      {:libsecp256k1, "~> 0.1.10"},
       # Log errors and application output to separate files
       {:logger_file_backend, "~> 0.0.10"},
       # Mocking `EthereumJSONRPC.Transport`, so we avoid hitting real chains for local testing

apps/indexer/test/indexer/block/util_test.exs

@@ -0,0 +1,40 @@
+defmodule Indexer.Block.UtilTest do
+  use ExUnit.Case
+
+  alias Indexer.Block.Util
+
+  test "signer/1" do
+    data = %{
+      difficulty: 1,
+      extra_data:
+        "0xd68301080d846765746886676f312e3130856c696e7578000000000000000000773ab2ca8f47904a14739ad80a75b71d9d29b9fff8b7ecdcb73efffa6f74122f17d304b5dc8e6e5f256c9474dd115c8d4dae31b7a3d409e5c3270f8fde41cd8c00",
+      gas_limit: 7_753_377,
+      gas_used: 1_810_195,
+      hash: "0x7004c895e812c55b0c2be8a46d72ca300a683dc27d1d7917ee7742d4d0359c1f",
+      logs_bloom:
+        "0x00000000000000020000000000002000000400000000000000000000000000000000000000000000040000080004000020000010000000000000000000000000000000000000000008000008000000000000000000200000000000000000000000000000020000000000000000000800000000000000804000000010080000000800000000000000000000000000000000000000000000800000000000080000000008000400000000404000000000000000000000000200000000000000000000000002000000000000001002000000000000002000000008000000000020000000000000000000000000000000000000000000000000400000800000000000",
+      miner: "0x0000000000000000000000000000000000000000",
+      mix_hash: "0x0000000000000000000000000000000000000000000000000000000000000000",
+      nonce: "0x0000000000000000",
+      number: 2_848_394,
+      parent_hash: "0x20350fc367e19d3865be1ea7da72ab81f8f9941c43ac6bb24a34a0a7caa2f3df",
+      receipts_root: "0x6ade4ac1079ea50cfadcce2b75ffbe4f9b14bf69b4607bbf1739463076ca6246",
+      sha3_uncles: "0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347",
+      size: 6437,
+      state_root: "0x23f63347851bcd109059d007d71e19c4f5e73b7f0862bebcd04458333a004d92",
+      timestamp: 1_534_796_040,
+      total_difficulty: 5_353_647,
+      transactions: [
+        "0x7e3bb851fc74a436826d2af6b96e4db9484431811ef0d9c9e78370488d33d4e5",
+        "0x3976fd1e3d2a715c3cfcfde9bd3210798c26c017b8edb841d319227ecb3322fb",
+        "0xd8db124005bb8b6fda7b71fd56ac782552a66af58fe843ba3c4930423b87d1d2",
+        "0x10c1a1ca4d9f4b2bd5b89f7bbcbbc2d69e166fe23662b8db4f6beae0f50ac9fd",
+        "0xaa58a6545677c796a56b8bc874174c8cfd31a6c6e6ca3a87e086d4f66d52858a"
+      ],
+      transactions_root: "0xde8d25c0b9b54310128a21601331094b43f910f9f96102869c2e2dca94884bf4",
+      uncles: []
+    }
+
+    assert Util.signer(data) == "0xfc18cbc391de84dbd87db83b20935d3e89f5dd91"
+  end
+end

mix.lock

@@ -32,6 +32,7 @@
   "ex_cldr_units": {:hex, :ex_cldr_units, "1.1.1", "b3c7256709bdeb3740a5f64ce2bce659eb9cf4cc1afb4cf94aba033b4a18bc5f", [:mix], [{:ex_cldr, "~> 1.0", [hex: :ex_cldr, optional: false]}, {:ex_cldr_numbers, "~> 1.0", [hex: :ex_cldr_numbers, optional: false]}]},
   "ex_doc": {:hex, :ex_doc, "0.19.1", "519bb9c19526ca51d326c060cb1778d4a9056b190086a8c6c115828eaccea6cf", [:mix], [{:earmark, "~> 1.1", [hex: :earmark, repo: "hexpm", optional: false]}, {:makeup_elixir, "~> 0.7", [hex: :makeup_elixir, repo: "hexpm", optional: false]}], "hexpm"},
   "ex_machina": {:hex, :ex_machina, "2.2.1", "df84d0b23487aaa8570c35e586d7f9f197a7787e1121344a41d8832a7ea41edf", [:mix], [{:ecto, "~> 2.1", [hex: :ecto, repo: "hexpm", optional: true]}], "hexpm"},
+  "ex_rlp": {:hex, :ex_rlp, "0.3.1", "190554f7b26f79734fc5a772241eec14a71b2e83576e43f451479feb017013e9", [:mix], [], "hexpm"},
   "exactor": {:hex, :exactor, "2.2.4", "5efb4ddeb2c48d9a1d7c9b465a6fffdd82300eb9618ece5d34c3334d5d7245b1", [:mix], []},
   "excoveralls": {:git, "https://github.com/KronicDeth/excoveralls.git", "0a859b68851eeba9b43eba59fbc8f9098299cfe1", [branch: "circle-workflows"]},
   "exjsx": {:hex, :exjsx, "4.0.0", "60548841e0212df401e38e63c0078ec57b33e7ea49b032c796ccad8cde794b5c", [:mix], [{:jsx, "~> 2.8.0", [hex: :jsx, optional: false]}]},
@@ -50,7 +51,7 @@
   "jsx": {:hex, :jsx, "2.8.3", "a05252d381885240744d955fbe3cf810504eb2567164824e19303ea59eef62cf", [:mix, :rebar3], []},
   "junit_formatter": {:hex, :junit_formatter, "2.2.0", "da6093f0740c58a824f9585ebb7cb1b960efaecf48d1fa969e95d9c47c6b19dd", [:mix], [], "hexpm"},
   "keccakf1600": {:hex, :keccakf1600_orig, "2.0.0", "0a7217ddb3ee8220d449bbf7575ec39d4e967099f220a91e3dfca4dbaef91963", [:rebar3], []},
-  "libsecp256k1": {:hex, :libsecp256k1, "0.1.4", "42b7f76d8e32f85f578ccda0abfdb1afa0c5c231d1fd8aeab9cda352731a2d83", [:rebar3], []},
+  "libsecp256k1": {:hex, :libsecp256k1, "0.1.10", "d27495e2b9851c7765129b76c53b60f5e275bd6ff68292c50536bf6b8d091a4d", [:make, :mix], [{:mix_erlang_tasks, "0.1.0", [hex: :mix_erlang_tasks, repo: "hexpm", optional: false]}], "hexpm"},
   "logger_file_backend": {:hex, :logger_file_backend, "0.0.10", "876f9f84ae110781207c54321ffbb62bebe02946fe3c13f0d7c5f5d8ad4fa910", [:mix], [], "hexpm"},
   "makeup": {:hex, :makeup, "0.5.5", "9e08dfc45280c5684d771ad58159f718a7b5788596099bdfb0284597d368a882", [:mix], [{:nimble_parsec, "~> 0.4", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm"},
   "makeup_elixir": {:hex, :makeup_elixir, "0.10.0", "0f09c2ddf352887a956d84f8f7e702111122ca32fbbc84c2f0569b8b65cbf7fa", [:mix], [{:makeup, "~> 0.5.5", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm"},
@@ -59,6 +60,7 @@
   "metrics": {:hex, :metrics, "1.0.1", "25f094dea2cda98213cecc3aeff09e940299d950904393b2a29d191c346a8486", [:rebar3], []},
   "mime": {:hex, :mime, "1.3.0", "5e8d45a39e95c650900d03f897fbf99ae04f60ab1daa4a34c7a20a5151b7a5fe", [:mix], [], "hexpm"},
   "mimerl": {:hex, :mimerl, "1.0.2", "993f9b0e084083405ed8252b99460c4f0563e41729ab42d9074fd5e52439be88", [:rebar3], []},
+  "mix_erlang_tasks": {:hex, :mix_erlang_tasks, "0.1.0", "36819fec60b80689eb1380938675af215565a89320a9e29c72c70d97512e4649", [:mix], [], "hexpm"},
   "mochiweb": {:hex, :mochiweb, "2.18.0", "eb55f1db3e6e960fac4e6db4e2db9ec3602cc9f30b86cd1481d56545c3145d2e", [:rebar3], [], "hexpm"},
   "mock": {:hex, :mock, "0.3.2", "e98e998fd76c191c7e1a9557c8617912c53df3d4a6132f561eb762b699ef59fa", [:mix], [{:meck, "~> 0.8.8", [hex: :meck, repo: "hexpm", optional: false]}], "hexpm"},
   "mox": {:hex, :mox, "0.4.0", "7f120840f7d626184a3d65de36189ca6f37d432e5d63acd80045198e4c5f7e6e", [:mix], [], "hexpm"},