feat: Add Action Signing and verification and Utilities

examples/src/examples/exampleUsage.js.

@@ -0,0 +1,24 @@
+import { signActionPayload } from '../utils/signActionPayload';
+
+const actionPayload = {
+    actionType: 'transfer',
+    amount: 500,
+    destination: 'G7huw9ZxyV6HX...Xnb6Vhvqpk',
+};
+
+async function signActionExample() {
+    const wallet = window.solana;
+
+    if (!wallet.isConnected) {
+        await wallet.connect();
+    }
+
+    try {
+        const signedAction = await signActionPayload(actionPayload, wallet);
+        console.log('Signed Action:', signedAction);
+    } catch (error) {
+        console.error('Error signing action:', error.message);
+    }
+}
+
+signActionExample();

src/utils/verifySignedAction.js.

@@ -0,0 +1,20 @@
+import { PublicKey } from '@solana/web3.js';
+import nacl from 'tweetnacl';
+import bs58 from 'bs58';
+
+/**
+ * Verifies the signed action payload.
+ *
+ * @param {Object} signedAction - The signed action payload with signature and publicKey.
+ * @returns {boolean} True if the signature is valid, false otherwise.
+ */
+export function verifySignedAction(signedAction) {
+    const { payload, signature, publicKey } = signedAction;
+    const message = new TextEncoder().encode(JSON.stringify(payload));
+
+    return nacl.sign.detached.verify(
+        message,
+        bs58.decode(signature),
+        new PublicKey(publicKey).toBytes()
+    );
+}