Add email communication system with encrypted credentials

- Add email components for composing, viewing threads, and credential setup
- Implement server API endpoints for sending emails and fetching threads
- Add encryption utilities for secure credential storage
- Configure email settings in environment variables
- Integrate email functionality into interest details modal

server/utils/encryption.ts

@@ -0,0 +1,117 @@
+import crypto from 'crypto';
+
+const algorithm = 'aes-256-gcm';
+const saltLength = 64;
+const tagLength = 16;
+const ivLength = 16;
+const iterations = 100000;
+const keyLength = 32;
+
+function getKey(): Buffer {
+  const key = process.env.NUXT_EMAIL_ENCRYPTION_KEY;
+  if (!key || key.length < 32) {
+    throw new Error('NUXT_EMAIL_ENCRYPTION_KEY must be at least 32 characters long');
+  }
+  // Ensure key is exactly 32 bytes
+  return Buffer.from(key.substring(0, 32).padEnd(32, '0'));
+}
+
+export function encryptCredentials(email: string, password: string): string {
+  try {
+    const key = getKey();
+    const iv = crypto.randomBytes(ivLength);
+    const salt = crypto.randomBytes(saltLength);
+    
+    const derivedKey = crypto.pbkdf2Sync(key, salt, iterations, keyLength, 'sha256');
+    const cipher = crypto.createCipheriv(algorithm, derivedKey, iv);
+    
+    const data = JSON.stringify({ email, password });
+    const encrypted = Buffer.concat([
+      cipher.update(data, 'utf8'),
+      cipher.final()
+    ]);
+    
+    const tag = cipher.getAuthTag();
+    
+    // Combine salt, iv, tag, and encrypted data
+    const combined = Buffer.concat([salt, iv, tag, encrypted]);
+    
+    return combined.toString('base64');
+  } catch (error) {
+    throw new Error('Failed to encrypt credentials');
+  }
+}
+
+export function decryptCredentials(encryptedData: string): { email: string; password: string } {
+  try {
+    const key = getKey();
+    const combined = Buffer.from(encryptedData, 'base64');
+    
+    // Extract components
+    const salt = combined.slice(0, saltLength);
+    const iv = combined.slice(saltLength, saltLength + ivLength);
+    const tag = combined.slice(saltLength + ivLength, saltLength + ivLength + tagLength);
+    const encrypted = combined.slice(saltLength + ivLength + tagLength);
+    
+    const derivedKey = crypto.pbkdf2Sync(key, salt, iterations, keyLength, 'sha256');
+    const decipher = crypto.createDecipheriv(algorithm, derivedKey, iv);
+    decipher.setAuthTag(tag);
+    
+    const decrypted = Buffer.concat([
+      decipher.update(encrypted),
+      decipher.final()
+    ]);
+    
+    return JSON.parse(decrypted.toString('utf8'));
+  } catch (error) {
+    throw new Error('Failed to decrypt credentials');
+  }
+}
+
+// In-memory session storage for credentials (cleared on server restart)
+const credentialCache = new Map<string, { credentials: string; timestamp: number }>();
+const CACHE_TTL = 30 * 60 * 1000; // 30 minutes
+
+export function storeCredentialsInSession(sessionId: string, encryptedCredentials: string): void {
+  credentialCache.set(sessionId, {
+    credentials: encryptedCredentials,
+    timestamp: Date.now()
+  });
+  
+  // Clean up expired sessions
+  cleanupExpiredSessions();
+}
+
+export function getCredentialsFromSession(sessionId: string): string | null {
+  const session = credentialCache.get(sessionId);
+  
+  if (!session) {
+    return null;
+  }
+  
+  // Check if session is expired
+  if (Date.now() - session.timestamp > CACHE_TTL) {
+    credentialCache.delete(sessionId);
+    return null;
+  }
+  
+  // Update timestamp on access
+  session.timestamp = Date.now();
+  return session.credentials;
+}
+
+export function clearCredentialsFromSession(sessionId: string): void {
+  credentialCache.delete(sessionId);
+}
+
+function cleanupExpiredSessions(): void {
+  const now = Date.now();
+  for (const [sessionId, session] of credentialCache.entries()) {
+    if (now - session.timestamp > CACHE_TTL) {
+      credentialCache.delete(sessionId);
+    }
+  }
+}
+
+// Cleanup expired sessions every 5 minutes
+setInterval(cleanupExpiredSessions, 5 * 60 * 1000);