From 304cd457c052e857bb6d2d5f5305baec00f43219 Mon Sep 17 00:00:00 2001
From: Julien Eluard <julien.eluard@gmail.com>
Date: Thu, 25 Jan 2024 16:56:52 +0100
Subject: [PATCH] feat: add ERC-55 support to ExecutionAddress

---
 packages/types/package.json              |  3 ++-
 packages/types/src/primitive/sszTypes.ts | 15 ++++++++++++++-
 packages/utils/package.json              |  1 +
 packages/utils/src/format.ts             | 24 +++++++++++++++++++++++-
 packages/utils/test/unit/format.test.ts  | 19 +++++++++++++++++++
 5 files changed, 59 insertions(+), 3 deletions(-)
 create mode 100644 packages/utils/test/unit/format.test.ts

diff --git a/packages/types/package.json b/packages/types/package.json
index 4497098c14f4..ce7265bdf211 100644
--- a/packages/types/package.json
+++ b/packages/types/package.json
@@ -74,7 +74,8 @@
   "types": "lib/index.d.ts",
   "dependencies": {
     "@chainsafe/ssz": "^0.14.0",
-    "@lodestar/params": "^1.14.0"
+    "@lodestar/params": "^1.14.0",
+    "@lodestar/utils": "^1.14.0"
   },
   "keywords": [
     "ethereum",
diff --git a/packages/types/src/primitive/sszTypes.ts b/packages/types/src/primitive/sszTypes.ts
index 65c81d1247b9..92b67a79e89e 100644
--- a/packages/types/src/primitive/sszTypes.ts
+++ b/packages/types/src/primitive/sszTypes.ts
@@ -1,4 +1,7 @@
 import {ByteVectorType, UintNumberType, UintBigintType, BooleanType} from "@chainsafe/ssz";
+/* eslint-disable no-restricted-imports */
+import {ByteArray} from "@chainsafe/ssz/lib/type/byteArray";
+import {toChecksumAddress} from "@lodestar/utils";
 
 export const Boolean = new BooleanType();
 export const Byte = new UintNumberType(1);
@@ -54,6 +57,16 @@ export const Wei = UintBn256;
 export const Root = new ByteVectorType(32);
 export const BlobIndex = UintNum64;
 
+export class ExecutionAddressType extends ByteVectorType {
+  constructor() {
+    super(20);
+  }
+  toJson(value: ByteArray): unknown {
+    const string = super.toJson(value) as string;
+    return toChecksumAddress(string);
+  }
+}
+
 export const Version = Bytes4;
 export const DomainType = Bytes4;
 export const ForkDigest = Bytes4;
@@ -61,4 +74,4 @@ export const BLSPubkey = Bytes48;
 export const BLSSignature = Bytes96;
 export const Domain = Bytes32;
 export const ParticipationFlags = new UintNumberType(1, {setBitwiseOR: true});
-export const ExecutionAddress = Bytes20;
+export const ExecutionAddress = new ExecutionAddressType();
diff --git a/packages/utils/package.json b/packages/utils/package.json
index db3ed9e06986..67bd6948be92 100644
--- a/packages/utils/package.json
+++ b/packages/utils/package.json
@@ -44,6 +44,7 @@
     "bigint-buffer": "^1.1.5",
     "case": "^1.6.3",
     "chalk": "^5.2.0",
+    "ethereum-cryptography": "^1.2.0",
     "js-yaml": "^4.1.0"
   },
   "devDependencies": {
diff --git a/packages/utils/src/format.ts b/packages/utils/src/format.ts
index 6a88ead41490..3c9cf513b5ee 100644
--- a/packages/utils/src/format.ts
+++ b/packages/utils/src/format.ts
@@ -1,4 +1,5 @@
-import {toHexString} from "./bytes.js";
+import {keccak256} from "ethereum-cryptography/keccak.js";
+import {fromHex, toHexString} from "./bytes.js";
 
 /**
  * Format bytes as `0x1234…1234`
@@ -27,3 +28,24 @@ export function truncBytes(root: Uint8Array | string): string {
   const str = typeof root === "string" ? root : toHexString(root);
   return str.slice(0, 14);
 }
+
+/**
+ * Formats an address according to [ERC55](https://eips.ethereum.org/EIPS/eip-55)
+ *
+ * @param address an hex address
+ * @returns an ERC55 formatted version of `address`
+ */
+export function toChecksumAddress(address: string): string {
+  const rawAddress = address.toLowerCase().startsWith("0x") ? address.slice(2) : address;
+  const bytes = fromHex(rawAddress);
+  const hash = toHexString(keccak256(bytes)).slice(2);
+  let checksumAddress = "0x";
+  for (let i = 0; i < rawAddress.length; i++) {
+    if (parseInt(hash[i], 16) >= 8) {
+      checksumAddress += rawAddress[i].toUpperCase();
+    } else {
+      checksumAddress += rawAddress[i];
+    }
+  }
+  return checksumAddress;
+}
diff --git a/packages/utils/test/unit/format.test.ts b/packages/utils/test/unit/format.test.ts
new file mode 100644
index 000000000000..524c0b570dba
--- /dev/null
+++ b/packages/utils/test/unit/format.test.ts
@@ -0,0 +1,19 @@
+import {describe, it, expect} from "vitest";
+import {toChecksumAddress} from "../../src/index.js";
+
+describe("toChecksumAddress", () => {
+  it("should format address as ERC55", () => {
+    expect(toChecksumAddress("52908400098527886E0F7030069857D2E4169EE7")).toBe(
+      "0x52908400098527886E0F7030069857D2E4169EE7"
+    );
+    expect(toChecksumAddress("0x52908400098527886E0F7030069857D2E4169EE7")).toBe(
+      "0x52908400098527886E0F7030069857D2E4169EE7"
+    );
+    expect(toChecksumAddress("0xde709f2102306220921060314715629080e2fb77")).toBe(
+      "0xdE709F2102306220921060314715629080e2fB77"
+    );
+    expect(toChecksumAddress("0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed")).toBe(
+      "0x5AAEB6053F3E94C9b9A09F33669435E7Ef1BeAED"
+    );
+  });
+});