From 54203b69f3c404483c23bab89a5ad048a29b9411 Mon Sep 17 00:00:00 2001
From: rileystephens28 <riley.stephens28@gmail.com>
Date: Wed, 26 Jun 2024 13:58:05 -0500
Subject: [PATCH] Add new ethereum backwards compatible message hash and verify
 methods

---
 src/constants/strings.ts | 12 ++++++++++-
 src/hash/index.ts        |  2 +-
 src/hash/message.ts      | 46 ++++++++++++++++++++++++++++++++++++----
 src/quais.ts             |  2 ++
 4 files changed, 56 insertions(+), 6 deletions(-)

diff --git a/src/constants/strings.ts b/src/constants/strings.ts
index 844e1ba5..6c63540d 100644
--- a/src/constants/strings.ts
+++ b/src/constants/strings.ts
@@ -9,6 +9,16 @@
  */
 export const quaisymbol: string = '\u039e'; // "\uD835\uDF63";
 
+/**
+ * A constant for the Quai Network equivalent of the [EIP-191](https://eips.ethereum.org/EIPS/eip-191) personal message
+ * prefix.
+ *
+ * (**i.e.** `"\\x19Quai Signed Message:\\n"`)
+ *
+ * @category Constants
+ */
+export const MessagePrefix: string = '\x19Quai Signed Message:\n';
+
 /**
  * A constant for the [EIP-191](https://eips.ethereum.org/EIPS/eip-191) personal message prefix.
  *
@@ -16,4 +26,4 @@ export const quaisymbol: string = '\u039e'; // "\uD835\uDF63";
  *
  * @category Constants
  */
-export const MessagePrefix: string = '\x19Quai Signed Message:\n';
+export const EthMessagePrefix: string = '\x19Ethereum Signed Message:\n';
diff --git a/src/hash/index.ts b/src/hash/index.ts
index 115f1c88..13eecb1b 100644
--- a/src/hash/index.ts
+++ b/src/hash/index.ts
@@ -3,7 +3,7 @@
  */
 
 export { id } from './id.js';
-export { hashMessage, verifyMessage } from './message.js';
+export { hashMessage, verifyMessage, ethHashMessage, ethVerifyMessage } from './message.js';
 export { solidityPacked, solidityPackedKeccak256, solidityPackedSha256 } from './solidity.js';
 export { TypedDataEncoder, verifyTypedData } from './typed-data.js';
 
diff --git a/src/hash/message.ts b/src/hash/message.ts
index 03d749c2..b630e678 100644
--- a/src/hash/message.ts
+++ b/src/hash/message.ts
@@ -4,10 +4,11 @@ import { recoverAddress } from '../address/index.js';
 import { concat } from '../utils/index.js';
 import { toUtf8Bytes } from '../encoding/index.js';
 
-
 import type { SignatureLike } from '../crypto/index.js';
+import { EthMessagePrefix } from '../constants/strings.js';
 /**
- * Computes the [EIP-191](https://eips.ethereum.org/EIPS/eip-191) personal-sign message digest to sign.
+ * Computes the Quai Network equivalent of the [EIP-191](https://eips.ethereum.org/EIPS/eip-191) personal-sign message
+ * digest to sign.
  *
  * This prefixes the message with {@link MessagePrefix | **MessagePrefix**} and the decimal length of `message` and
  * computes the {@link keccak256 | **keccak256**} digest.
@@ -37,7 +38,6 @@ import type { SignatureLike } from '../crypto/index.js';
  * ```
  *
  * @param {Uint8Array | string} message - The message to hash.
- *
  * @returns {string} The message digest.
  */
 export function hashMessage(message: Uint8Array | string): string {
@@ -53,10 +53,48 @@ export function hashMessage(message: Uint8Array | string): string {
  * @category Hash
  * @param {Uint8Array | string} message - The message that was signed.
  * @param {SignatureLike} sig - The signature to verify.
- *
  * @returns {string} The address of the signer.
  */
 export function verifyMessage(message: Uint8Array | string, sig: SignatureLike): string {
     const digest = hashMessage(message);
     return recoverAddress(digest, sig);
 }
+
+/**
+ * Computes the [EIP-191](https://eips.ethereum.org/EIPS/eip-191) personal-sign message digest to sign.
+ *
+ * This prefixes the message with {@link EthMessagePrefix | **EthMessagePrefix**} and the decimal length of `message` and
+ * computes the {@link keccak256 | **keccak256**} digest.
+ *
+ * If `message` is a string, it is converted to its UTF-8 bytes first. To compute the digest of a
+ * [**DataHexString**](../types-aliases/DataHex), it must be converted to [**bytes**](../functions/getBytes).
+ *
+ * This is the same as `hashMessage` except it uses `EthMessagePrefix` instead of `MessagePrefix` and is available for
+ * broader compatibility with EVM signing practices.
+ *
+ * @category Hash
+ * @param message
+ * @returns
+ */
+export function ethHashMessage(message: Uint8Array | string): string {
+    if (typeof message === 'string') {
+        message = toUtf8Bytes(message);
+    }
+    return keccak256(concat([toUtf8Bytes(EthMessagePrefix), toUtf8Bytes(String(message.length)), message]));
+}
+
+/**
+ * Return the address of the private key that produced the signature `sig` during signing for `message`.
+ *
+ * This is the same as `verifyMessage` except it uses `EthMessagePrefix` instead of `MessagePrefix` and is available for
+ * broader compatibility with EVM signing practices.
+ *
+ * @category Hash
+ * @param message - The message that was signed.
+ * @param sig - The signature to verify.
+ * @returns {string} The address of the signer.
+ */
+export function ethVerifyMessage(message: Uint8Array | string, sig: SignatureLike): string {
+    const digest = ethHashMessage(message);
+    return recoverAddress(digest, sig);
+}
diff --git a/src/quais.ts b/src/quais.ts
index e2d010da..94ca95e3 100644
--- a/src/quais.ts
+++ b/src/quais.ts
@@ -89,6 +89,8 @@ export {
     id,
     hashMessage,
     verifyMessage,
+    ethHashMessage,
+    ethVerifyMessage,
     solidityPacked,
     solidityPackedKeccak256,
     solidityPackedSha256,