From a8b122dd85db91eecb4e70dcf986e2cd4456619c Mon Sep 17 00:00:00 2001
From: Benjamin Smith <bh2smith@users.noreply.github.com>
Date: Thu, 25 Apr 2024 13:08:50 +0200
Subject: [PATCH] Adapter.signMessage (#23)

---
 examples/sign-message.ts | 14 ++++++++++
 package.json             |  2 +-
 src/chains/ethereum.ts   | 58 +++++++++++++++++++++++++++++++++++++++-
 tests/e2e.test.ts        |  8 ++++--
 yarn.lock                | 15 ++++++++++-
 5 files changed, 92 insertions(+), 5 deletions(-)
 create mode 100644 examples/sign-message.ts

diff --git a/examples/sign-message.ts b/examples/sign-message.ts
new file mode 100644
index 0000000..601358d
--- /dev/null
+++ b/examples/sign-message.ts
@@ -0,0 +1,14 @@
+import dotenv from "dotenv";
+import { setupNearEthAdapter } from "./setup";
+dotenv.config();
+
+const run = async (): Promise<void> => {
+  const evm = await setupNearEthAdapter();
+  const message = "Hello World";
+  console.log(`Signing "${message}" with ${evm.ethPublicKey()}`);
+
+  const signature = await evm.signMessage(message);
+  console.log("Got Validated Signature", signature);
+};
+
+run();
diff --git a/package.json b/package.json
index f02abef..bb5e999 100644
--- a/package.json
+++ b/package.json
@@ -21,7 +21,7 @@
     "@typescript-eslint/parser": "^7.2.0",
     "dotenv": "^16.4.5",
     "eslint": "^8.57.0",
-    "ethers": "v6",
+    "ethers": "^6.12.0",
     "jest": "^29.7.0",
     "opensea-js": "^7.0.9",
     "prettier": "^3.2.5",
diff --git a/src/chains/ethereum.ts b/src/chains/ethereum.ts
index 13f2fc7..c84eb50 100644
--- a/src/chains/ethereum.ts
+++ b/src/chains/ethereum.ts
@@ -6,6 +6,12 @@ import {
   http,
   Hash,
   serializeTransaction,
+  hashMessage,
+  toBytes,
+  isBytes,
+  SignableMessage,
+  verifyMessage,
+  signatureToHex,
 } from "viem";
 import {
   BaseTx,
@@ -18,6 +24,7 @@ import { MultichainContract } from "../mpcContract";
 import BN from "bn.js";
 import { queryGasPrice } from "../utils/gasPrice";
 import { buildTxPayload, addSignature } from "../utils/transaction";
+// import { ethers } from "ethers";
 
 export class NearEthAdapter {
   ethClient: PublicClient;
@@ -92,7 +99,7 @@ export class NearEthAdapter {
       signArgs,
       nearGas
     );
-
+    console.log("Signature received");
     return this.relayTransaction({ transaction, signature: { big_r, big_s } });
   }
 
@@ -202,4 +209,53 @@ export class NearEthAdapter {
     console.log(`Transaction Confirmed: ${this.scanUrl}/tx/${txHash}`);
     return txHash;
   }
+  // Below code is inspired by https://github.com/Connor-ETHSeoul/near-viem
+
+  async signMessage(message: SignableMessage): Promise<Hash> {
+    const sigs = await this.sign(hashMessage(message));
+    const address = this.ethPublicKey();
+    const validity = await Promise.all([
+      verifyMessage({
+        address,
+        message,
+        signature: sigs[0],
+      }),
+      verifyMessage({
+        address,
+        message: message,
+        signature: sigs[1],
+      }),
+    ]);
+    return this.pickValidSignature(validity, sigs);
+  }
+
+  async sign(msgHash: `0x${string}` | Uint8Array): Promise<[Hex, Hex]> {
+    const hashToSign = isBytes(msgHash) ? msgHash : toBytes(msgHash);
+
+    const { big_r, big_s } = await this.mpcContract.requestSignature({
+      path: this.derivationPath,
+      payload: Array.from(hashToSign.reverse()),
+      key_version: 0,
+    });
+    const r = `0x${big_r.substring(2)}` as Hex;
+    const s = `0x${big_s}` as Hex;
+
+    return [
+      signatureToHex({ r, s, yParity: 0 }),
+      signatureToHex({ r, s, yParity: 1 }),
+    ];
+  }
+
+  private pickValidSignature(
+    [valid0, valid1]: [boolean, boolean],
+    [sig0, sig1]: [Hash, Hash]
+  ): Hash {
+    if (!valid0 && !valid1) {
+      throw new Error("Invalid signature");
+    } else if (valid0) {
+      return sig0;
+    } else {
+      return sig1;
+    }
+  }
 }
diff --git a/tests/e2e.test.ts b/tests/e2e.test.ts
index deb0ce1..f32e0e1 100644
--- a/tests/e2e.test.ts
+++ b/tests/e2e.test.ts
@@ -15,13 +15,13 @@ describe("End To End", () => {
     clearTimeout();
   });
 
-  it("Runs the Send ETH Tx", async () => {
+  it("signAndSendTransaction", async () => {
     await expect(
       evm.signAndSendTransaction({ to, value: ONE_WEI })
     ).resolves.not.toThrow();
   });
 
-  it("Fails Invalid Send ETH Tx", async () => {
+  it("Fails to sign and send", async () => {
     const senderBalance = await getBalance(evm.ethClient, {
       address: evm.ethPublicKey(),
     });
@@ -29,4 +29,8 @@ describe("End To End", () => {
       evm.signAndSendTransaction({ to, value: senderBalance + ONE_WEI })
     ).rejects.toThrow();
   });
+
+  it("signMessage", async () => {
+    await expect(evm.signMessage("NearEth")).resolves.not.toThrow();
+  });
 });
diff --git a/yarn.lock b/yarn.lock
index b305817..c9526e5 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1936,7 +1936,20 @@ ethereum-cryptography@^2.0.0, ethereum-cryptography@^2.1.2:
     "@scure/bip32" "1.3.3"
     "@scure/bip39" "1.2.2"
 
-ethers@^6.9.0, ethers@v6:
+ethers@^6.12.0:
+  version "6.12.0"
+  resolved "https://registry.yarnpkg.com/ethers/-/ethers-6.12.0.tgz#b0c2ce207ae5a3b5125be966e32ffea7c1f2481a"
+  integrity sha512-zL5NlOTjML239gIvtVJuaSk0N9GQLi1Hom3ZWUszE5lDTQE/IVB62mrPkQ2W1bGcZwVGSLaetQbWNQSvI4rGDQ==
+  dependencies:
+    "@adraffy/ens-normalize" "1.10.1"
+    "@noble/curves" "1.2.0"
+    "@noble/hashes" "1.3.2"
+    "@types/node" "18.15.13"
+    aes-js "4.0.0-beta.5"
+    tslib "2.4.0"
+    ws "8.5.0"
+
+ethers@^6.9.0:
   version "6.11.1"
   resolved "https://registry.yarnpkg.com/ethers/-/ethers-6.11.1.tgz#96aae00b627c2e35f9b0a4d65c7ab658259ee6af"
   integrity sha512-mxTAE6wqJQAbp5QAe/+o+rXOID7Nw91OZXvgpjDa1r4fAbq2Nu314oEZSbjoRLacuCzs7kUC3clEvkCQowffGg==