feat: Enhance Nostr chat encryption with key validation and logging

- Implement validation for private and public keys before encryption, ensuring they are present and in the correct hex format.
- Add detailed console logging for key lengths and encryption success, improving debugging and transparency in the message encryption process.
- Refactor the encryption call to use validated keys, enhancing security and reliability.

src/composables/useNostrChat.ts

@@ -381,13 +381,45 @@ export function useNostrChat() {
     }
 
     try {
+      // Validate keys before encryption
+      if (!currentUser.value.prvkey || !peerPubkey) {
+        throw new Error('Missing private key or peer public key')
+      }
+      
+      // Ensure keys are in correct hex format (64 characters for private key, 64 characters for public key)
+      const privateKey = currentUser.value.prvkey.startsWith('0x') 
+        ? currentUser.value.prvkey.slice(2) 
+        : currentUser.value.prvkey
+      
+      const publicKey = peerPubkey.startsWith('0x') 
+        ? peerPubkey.slice(2) 
+        : peerPubkey
+      
+      if (privateKey.length !== 64) {
+        throw new Error(`Invalid private key length: ${privateKey.length} (expected 64)`)
+      }
+      
+      if (publicKey.length !== 64) {
+        throw new Error(`Invalid public key length: ${publicKey.length} (expected 64)`)
+      }
+      
+      console.log('Encrypting message with keys:', {
+        privateKeyLength: privateKey.length,
+        publicKeyLength: publicKey.length,
+        privateKeyPrefix: privateKey.slice(0, 8) + '...',
+        publicKeyPrefix: publicKey.slice(0, 8) + '...',
+        contentLength: content.length
+      })
+      
       // Encrypt the message
       const encryptedContent = await nip04.encrypt(
-        currentUser.value.prvkey,
-        peerPubkey,
+        privateKey,
+        publicKey,
         content
       )
       
+      console.log('Message encrypted successfully, length:', encryptedContent.length)
+
       // Create the event template
       const eventTemplate: EventTemplate = {
         kind: 4,
@@ -397,7 +429,7 @@ export function useNostrChat() {
       }
 
       // Finalize the event (sign it)
-      const event = finalizeEvent(eventTemplate, hexToBytes(currentUser.value.prvkey))
+      const event = finalizeEvent(eventTemplate, hexToBytes(privateKey))
 
       // Publish to relays
       const relayConfigs = getRelays()

src/lib/utils/crypto.ts

@@ -6,16 +6,26 @@
  * Convert hex string to Uint8Array
  */
 export function hexToBytes(hex: string): Uint8Array {
+  if (typeof hex !== 'string') {
+    throw new TypeError('hexToBytes: expected string, got ' + typeof hex)
+  }
+  
   if (hex.length % 2 !== 0) {
-    throw new Error('Hex string must have even length')
+    throw new Error('hexToBytes: received invalid unpadded hex')
   }
   
-  const bytes = hex.match(/.{2}/g)?.map(byte => parseInt(byte, 16))
-  if (!bytes) {
-    throw new Error('Invalid hex string')
+  const array = new Uint8Array(hex.length / 2)
+  for (let i = 0; i < array.length; i++) {
+    const j = i * 2
+    const hexByte = hex.slice(j, j + 2)
+    const byte = Number.parseInt(hexByte, 16)
+    if (Number.isNaN(byte) || byte < 0) {
+      throw new Error('Invalid byte sequence')
+    }
+    array[i] = byte
   }
   
-  return new Uint8Array(bytes)
+  return array
 }
 
 /**