From 78d5af4683631ca24e861d5e746b211192942fe8 Mon Sep 17 00:00:00 2001
From: Ben Smith <bh2smith@gmail.com>
Date: Thu, 25 Apr 2024 13:36:50 +0200
Subject: [PATCH] Sign Typed Data

---
 src/chains/ethereum.ts | 43 +++++++++++++++++++++++++++++++++++++-----
 tests/e2e.test.ts      | 42 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 80 insertions(+), 5 deletions(-)

diff --git a/src/chains/ethereum.ts b/src/chains/ethereum.ts
index c84eb50..749d02b 100644
--- a/src/chains/ethereum.ts
+++ b/src/chains/ethereum.ts
@@ -11,7 +11,11 @@ import {
   isBytes,
   SignableMessage,
   verifyMessage,
+  verifyTypedData,
   signatureToHex,
+  hashTypedData,
+  TypedData,
+  TypedDataDefinition,
 } from "viem";
 import {
   BaseTx,
@@ -211,19 +215,48 @@ export class NearEthAdapter {
   }
   // Below code is inspired by https://github.com/Connor-ETHSeoul/near-viem
 
+  async signTypedData<
+    const typedData extends TypedData | Record<string, unknown>,
+    primaryType extends keyof typedData | "EIP712Domain" = keyof typedData,
+  >(typedData: TypedDataDefinition<typedData, primaryType>): Promise<Hash> {
+    const sigs = await this.sign(hashTypedData(typedData));
+
+    const common = {
+      address: this.ethPublicKey(),
+      types: typedData.types,
+      /* eslint-disable @typescript-eslint/no-explicit-any */
+      primaryType: typedData.primaryType as any,
+      message: typedData.message as any,
+      domain: typedData.domain as any,
+      /* eslint-enable @typescript-eslint/no-explicit-any */
+    };
+    const validity = await Promise.all([
+      verifyTypedData({
+        signature: sigs[0],
+        ...common,
+      }),
+      verifyTypedData({
+        signature: sigs[1],
+        ...common,
+      }),
+    ]);
+    return this.pickValidSignature(validity, sigs);
+  }
+
   async signMessage(message: SignableMessage): Promise<Hash> {
     const sigs = await this.sign(hashMessage(message));
-    const address = this.ethPublicKey();
+    const common = {
+      address: this.ethPublicKey(),
+      message,
+    };
     const validity = await Promise.all([
       verifyMessage({
-        address,
-        message,
         signature: sigs[0],
+        ...common,
       }),
       verifyMessage({
-        address,
-        message: message,
         signature: sigs[1],
+        ...common,
       }),
     ]);
     return this.pickValidSignature(validity, sigs);
diff --git a/tests/e2e.test.ts b/tests/e2e.test.ts
index f32e0e1..da3e29c 100644
--- a/tests/e2e.test.ts
+++ b/tests/e2e.test.ts
@@ -33,4 +33,46 @@ describe("End To End", () => {
   it("signMessage", async () => {
     await expect(evm.signMessage("NearEth")).resolves.not.toThrow();
   });
+
+  it("signTypedData", async () => {
+    const message = {
+      from: {
+        name: "Cow",
+        wallet: "0xCD2a3d9F938E13CD947Ec05AbC7FE734Df8DD826",
+      },
+      to: {
+        name: "Bob",
+        wallet: "0xbBbBBBBbbBBBbbbBbbBbbbbBBbBbbbbBbBbbBBbB",
+      },
+      contents: "Hello, Bob!",
+    } as const;
+
+    const domain = {
+      name: "Ether Mail",
+      version: "1",
+      chainId: 1,
+      verifyingContract: "0xCcCCccccCCCCcCCCCCCcCcCccCcCCCcCcccccccC",
+    } as const;
+
+    const types = {
+      Person: [
+        { name: "name", type: "string" },
+        { name: "wallet", type: "address" },
+      ],
+      Mail: [
+        { name: "from", type: "Person" },
+        { name: "to", type: "Person" },
+        { name: "contents", type: "string" },
+      ],
+    } as const;
+
+    await expect(
+      evm.signTypedData({
+        types,
+        primaryType: "Mail",
+        message,
+        domain,
+      })
+    ).resolves.not.toThrow();
+  });
 });