fixed public/private key stuff

izelnakri · Aug 30, 2017 · 1882521 · 1882521
1 parent 0f7fe0e
commit 1882521
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Showing 2 changed files with 18 additions and 10 deletions.
diff --git a/lib/eth/utils.ex b/lib/eth/utils.ex
@@ -5,35 +5,38 @@ defmodule ETH.Utils do
   end
 
   def get_public_key(<< private_key :: binary-size(32) >>) do
-    {public_key, ^private_key} = :crypto.generate_key(:ecdh, :secp256k1, private_key)
+    {:ok, public_key} = :libsecp256k1.ec_pubkey_create(private_key, :uncompressed)
     public_key
   end
   def get_public_key(<< encoded_private_key :: binary-size(64) >>) do
     private_key = Base.decode16!(encoded_private_key, case: :mixed)
-    {public_key, ^private_key} = :crypto.generate_key(:ecdh, :secp256k1, private_key)
+    {:ok, public_key} = :libsecp256k1.ec_pubkey_create(private_key, :uncompressed)
     public_key
   end
 
   def get_address(<< private_key :: binary-size(32) >>) do
-    public_key = private_key |> get_public_key()
-    << _ :: binary-size(12), eth_address :: binary-size(20) >> = keccak256(public_key)
+    << 4 :: size(8), key :: binary-size(64) >> = private_key |> get_public_key()
+    << _ :: binary-size(12), eth_address :: binary-size(20) >> = keccak256(key)
     "0x#{Base.encode16(eth_address)}"
   end
   def get_address(<< encoded_private_key :: binary-size(64) >>) do
-    public_key = Base.decode16!(encoded_private_key, case: :mixed) |> get_public_key()
-    << _ :: binary-size(12), eth_address :: binary-size(20) >> = keccak256(public_key)
+    << 4 :: size(8), key :: binary-size(64) >> = Base.decode16!(encoded_private_key) |> get_public_key()
+    << _ :: binary-size(12), eth_address :: binary-size(20) >> = keccak256(key)
     "0x#{Base.encode16(eth_address)}"
   end
-  def get_address(<< public_key :: binary-size(65) >>) do
-    << _ :: binary-size(12), eth_address :: binary-size(20) >> = keccak256(public_key)
+  def get_address(<< 4 :: size(8), key :: binary-size(64) >>) do
+    << _ :: binary-size(12), eth_address :: binary-size(20) >> = keccak256(key)
     "0x#{Base.encode16(eth_address)}"
   end
   def get_address(<< encoded_public_key :: binary-size(130) >>) do
-    public_key = Base.decode16!(encoded_public_key, case: :mixed)
-    << _ :: binary-size(12), eth_address :: binary-size(20) >> = keccak256(public_key)
+    << 4 :: size(8), key :: binary-size(64) >> = Base.decode16!(encoded_public_key)
+    << _ :: binary-size(12), eth_address :: binary-size(20) >> = keccak256(key)
     "0x#{Base.encode16(eth_address)}"
   end
 
   def keccak256(data), do: :keccakf1600.hash(:sha3_256, data)
   defp encode16(value), do: Base.encode16(value, case: :lower)
 end
+
+# NOTE: old version that is error-prone:
+# {public_key, ^private_key} = :crypto.generate_key(:ecdh, :secp256k1, private_key)
diff --git a/test/eth/utils_test.exs b/test/eth/utils_test.exs
@@ -14,6 +14,11 @@ defmodule ETH.UtilsTest do
     assert public_key |> byte_size == 65
     assert public_key == ETH.Utils.get_public_key(private_key)
     assert public_key != ETH.Utils.get_public_key(another_private_key)
+
+    1..1000 |> Enum.each(fn(x) ->
+      private_key = :crypto.strong_rand_bytes(32)
+      ETH.Utils.get_public_key(private_key)
+    end)
   end
 
   test "get_public_key/1 works for encoded private keys" do