Merge pull request #97 from casper-ecosystem/sign-msg

SignMessage implemented

CHANGELOG.md

@@ -4,6 +4,13 @@ All notable changes to casper-js-sdk.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/), and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## 2.5.0
+
+### Added
+
+- `signMessage` - added method to sign arbitrary string message
+- `verifyMessageSignature` - added method to verify signature of arbitrary string message
+
 ## 2.4.1
 
 ### Fixed

package.json

@@ -1,6 +1,6 @@
 {
   "name": "casper-js-sdk",
-  "version": "2.4.1",
+  "version": "2.5.0",
   "license": "Apache 2.0",
   "description": "SDK to interact with the Casper blockchain",
   "homepage": "https://github.com/casper-ecosystem/casper-js-sdk#README.md",

src/lib/SignedMessage.ts

@@ -0,0 +1,47 @@
+import * as nacl from 'tweetnacl-ts';
+import * as secp256k1 from 'ethereum-cryptography/secp256k1';
+import { sha256 } from 'ethereum-cryptography/sha256';
+
+import { CLPublicKey } from './CLValue/';
+import { AsymmetricKey } from './Keys';
+
+/**
+ * Method for signing string message.
+ * @param key AsymmetricKey used to sign the message
+ * @param message Message that will be signed
+ * @return Uint8Array Signature in byte format
+ */
+export const signMessage = (
+  key: AsymmetricKey,
+  message: string
+): Uint8Array => {
+  const messageWithHeader = Buffer.from(`Casper Message:\n${message}`);
+  return key.sign(messageWithHeader);
+};
+
+/**
+ * Method to verify signature
+ * @param key Public key of private key used to signed.
+ * @param message Message that was signed
+ * @param signature Signature in byte format
+ * @return boolean Verification result
+ */
+export const verifyMessageSignature = (
+  key: CLPublicKey,
+  message: string,
+  signature: Uint8Array
+): boolean => {
+  const messageWithHeader = Buffer.from(`Casper Message:\n${message}`);
+  if (key.isEd25519()) {
+    return nacl.sign_detached_verify(messageWithHeader, signature, key.value());
+  }
+  if (key.isSecp256K1()) {
+    return secp256k1.ecdsaVerify(
+      signature,
+      sha256(messageWithHeader),
+      key.value()
+    );
+  }
+
+  throw new Error('Unsupported algorithm.');
+};

src/lib/index.ts

@@ -6,5 +6,6 @@ import * as Signer from './Signer';
 export * from './CLValue';
 export * from './RuntimeArgs';
 export * from './CasperClient';
+export * from './SignedMessage';
 
 export { Contracts, Keys, Serialization, DeployUtil, Signer };

test/lib/SignedMessage.test.ts

@@ -0,0 +1,31 @@
+import { expect } from 'chai';
+import { Ed25519, Secp256K1 } from '../../src/lib/Keys';
+import { signMessage, verifyMessageSignature } from '../../src/index';
+
+describe('SignedMessage', () => {
+  it('Should generate proper signed message and validate it (Ed25519)', () => {
+    const signKeyPair = Ed25519.new();
+    const exampleMessage = "Hello World!";
+    const wrongMessage = "!Hello World";
+
+    const signature = signMessage(signKeyPair, exampleMessage);
+    const valid = verifyMessageSignature(signKeyPair.publicKey, exampleMessage, signature);
+    const invalid = verifyMessageSignature(signKeyPair.publicKey, wrongMessage, signature);
+
+    expect(valid).to.be.eq(true);
+    expect(invalid).to.be.eq(false);
+  });
+
+  it('Should generate proper signed message and validate it (Secp256K1)', () => {
+    const signKeyPair = Secp256K1.new();
+    const exampleMessage = "Hello World!";
+    const wrongMessage = "!Hello World";
+
+    const signature = signMessage(signKeyPair, exampleMessage);
+    const valid = verifyMessageSignature(signKeyPair.publicKey, exampleMessage, signature);
+    const invalid = verifyMessageSignature(signKeyPair.publicKey, wrongMessage, signature);
+
+    expect(valid).to.be.eq(true);
+    expect(invalid).to.be.eq(false);
+  });
+});