From bc9c4e9574cc453af35705eb4488602ea33cc2cb Mon Sep 17 00:00:00 2001
From: Janek Rahrt <janek.rahrt@me.com>
Date: Fri, 21 Jan 2022 15:03:15 +0100
Subject: [PATCH] feat: implement verifyMessage and verifyMessageHash

---
 src/signer/default.ts   | 39 ++++++++++++++++++++++++++++++++++++++-
 src/signer/interface.ts | 22 ++++++++++++++++++++++
 2 files changed, 60 insertions(+), 1 deletion(-)

diff --git a/src/signer/default.ts b/src/signer/default.ts
index 91e54bd30..cfb1e8d48 100644
--- a/src/signer/default.ts
+++ b/src/signer/default.ts
@@ -1,11 +1,12 @@
 import assert from 'minimalistic-assert';
 
+import { compileCalldata } from '../contract';
 import { Provider } from '../provider';
 import { AddTransactionResponse, KeyPair, Signature, Transaction } from '../types';
 import { sign } from '../utils/ellipticCurve';
 import { addHexPrefix } from '../utils/encode';
 import { hashMessage } from '../utils/hash';
-import { toBN } from '../utils/number';
+import { BigNumberish, toBN } from '../utils/number';
 import { getSelectorFromName } from '../utils/stark';
 import { TypedData, getMessageHash } from '../utils/typedData';
 import { SignerInterface } from './interface';
@@ -98,4 +99,40 @@ export class Signer extends Provider implements SignerInterface {
   public async hashMessage(typedData: TypedData): Promise<string> {
     return getMessageHash(typedData, this.address);
   }
+
+  /**
+   * Verify a signature of a JSON object
+   *
+   * @param json - JSON object to be verified
+   * @param signature - signature of the JSON object
+   * @returns true if the signature is valid, false otherwise
+   * @throws {Error} if the JSON object is not a valid JSON or the signature is not a valid signature
+   */
+  public async verifyMessageHash(hash: BigNumberish, signature: Signature): Promise<boolean> {
+    const { result } = await this.callContract({
+      contract_address: this.address,
+      entry_point_selector: getSelectorFromName('is_valid_signature'),
+      calldata: compileCalldata({
+        hash: toBN(hash).toString(),
+        signature: signature.map((x) => toBN(x).toString()),
+      }),
+    });
+
+    // 0 is false, 1 is true
+    return Boolean(toBN(result[0]).toNumber());
+  }
+
+  /**
+   * Verify a signature of a given hash
+   * @warning This method is not recommended, use verifyMessage instead
+   *
+   * @param hash - hash to be verified
+   * @param signature - signature of the hash
+   * @returns true if the signature is valid, false otherwise
+   * @throws {Error} if the signature is not a valid signature
+   */
+  public async verifyMessage(typedData: TypedData, signature: Signature): Promise<boolean> {
+    const hash = await this.hashMessage(typedData);
+    return this.verifyMessageHash(hash, signature);
+  }
 }
diff --git a/src/signer/interface.ts b/src/signer/interface.ts
index 5ea9cdf66..7144febf1 100644
--- a/src/signer/interface.ts
+++ b/src/signer/interface.ts
@@ -1,5 +1,6 @@
 import { Provider } from '../provider';
 import { AddTransactionResponse, Signature, Transaction } from '../types';
+import { BigNumberish } from '../utils/number';
 import { TypedData } from '../utils/typedData/types';
 
 export abstract class SignerInterface extends Provider {
@@ -35,4 +36,25 @@ export abstract class SignerInterface extends Provider {
    * @throws {Error} if the JSON object is not a valid JSON
    */
   public abstract hashMessage(typedData: TypedData): Promise<string>;
+
+  /**
+   * Verify a signature of a JSON object
+   *
+   * @param json - JSON object to be verified
+   * @param signature - signature of the JSON object
+   * @returns true if the signature is valid, false otherwise
+   * @throws {Error} if the JSON object is not a valid JSON or the signature is not a valid signature
+   */
+  public abstract verifyMessage(typedData: TypedData, signature: Signature): Promise<boolean>;
+
+  /**
+   * Verify a signature of a given hash
+   * @warning This method is not recommended, use verifyMessage instead
+   *
+   * @param hash - hash to be verified
+   * @param signature - signature of the hash
+   * @returns true if the signature is valid, false otherwise
+   * @throws {Error} if the signature is not a valid signature
+   */
+  public abstract verifyMessageHash(hash: BigNumberish, signature: Signature): Promise<boolean>;
 }