From 7b13af118401b1acac903f1e869c59dec4516375 Mon Sep 17 00:00:00 2001
From: Yaroslav Vorobiov <yar.vorobiov@gmail.com>
Date: Sun, 30 Oct 2022 15:19:16 +0100
Subject: [PATCH] private/blockchain: address checksum hex

Updates blockchain.Address.Hex to return mixedcase
checksum hash.

Change-Id: I74c830b49eceb30876c8ef20d3adc4816de51a64
---
 private/blockchain/types.go      | 18 ++++++++++++++++++
 private/blockchain/types_test.go | 22 ++++++++++++----------
 2 files changed, 30 insertions(+), 10 deletions(-)

diff --git a/private/blockchain/types.go b/private/blockchain/types.go
index 1bde7e42f..3b46ead60 100644
--- a/private/blockchain/types.go
+++ b/private/blockchain/types.go
@@ -9,6 +9,7 @@ import (
 	"reflect"
 
 	"github.com/zeebo/errs"
+	"golang.org/x/crypto/sha3"
 )
 
 // Error for the package (mainly parsing errors).
@@ -61,6 +62,23 @@ func (a Address) Hex() string {
 	var buf [len(a)*2 + 2]byte
 	copy(buf[:2], "0x")
 	hex.Encode(buf[2:], a[:])
+
+	// https://eips.ethereum.org/EIPS/eip-55
+	sha := sha3.NewLegacyKeccak256()
+	sha.Write(buf[2:])
+	hash := sha.Sum(nil)
+	for i := 2; i < len(buf); i++ {
+		hashByte := hash[(i-2)/2]
+		if i%2 == 0 {
+			hashByte >>= 4
+		} else {
+			hashByte &= 0xf
+		}
+		if buf[i] > '9' && hashByte > 7 {
+			buf[i] -= 32
+		}
+	}
+
 	return string(buf[:])
 }
 
diff --git a/private/blockchain/types_test.go b/private/blockchain/types_test.go
index fc37cb699..38b29211e 100644
--- a/private/blockchain/types_test.go
+++ b/private/blockchain/types_test.go
@@ -21,18 +21,12 @@ func TestBytesToAddress(t *testing.T) {
 	require.Error(t, err)
 }
 
-func TestHex(t *testing.T) {
+func TestAddressHex(t *testing.T) {
 	addresses := []string{
-		"0xd15aaacddf4b72ba8fc5c41fc4b03f05aa73385c",
-		"0xbe8f1abb014ec9988b6185ab4d8870992e838231",
-		"0xd24400ae8bfebb18ca49be86258a3c749cf46853",
+		"0xDAFEA492D9c6733ae3d56b7Ed1ADB60692c98Bc5",
+		"0xd24400ae8BfEBb18cA49Be86258a3C749cf46853",
+		"0x4E58657CD8b3401B6f7Db9Cd0408f06582c458b5",
 	}
-	hashes := []string{
-		"0xdea1082dbea119c822dfe804264f5b880d4208ef51e8c5a8995eff10a5094de8",
-		"0xd1a78f16158b550945dd39182d188c3fb7285b431223c8b0fe38f4181e9ac197",
-		"0x47a5b3fae0bad45631a65324001f75dea311898e26ee10597a66953b57dfe332",
-	}
-
 	for _, address := range addresses {
 		decoded, err := hex.DecodeString(address[2:])
 		require.NoError(t, err)
@@ -42,6 +36,14 @@ func TestHex(t *testing.T) {
 
 		require.Equal(t, address, a.Hex())
 	}
+}
+
+func TestHashHex(t *testing.T) {
+	hashes := []string{
+		"0xdea1082dbea119c822dfe804264f5b880d4208ef51e8c5a8995eff10a5094de8",
+		"0xd1a78f16158b550945dd39182d188c3fb7285b431223c8b0fe38f4181e9ac197",
+		"0x47a5b3fae0bad45631a65324001f75dea311898e26ee10597a66953b57dfe332",
+	}
 	for _, hash := range hashes {
 		decoded, err := hex.DecodeString(hash[2:])
 		require.NoError(t, err)