All sensitive financial data encrypted at rest using AES-256+

Unencrypted financial data at rest — account numbers, SSNs, card tokens, transaction history — is a direct path from database breach to identity theft and fraud. CWE-311 (missing encryption) and CWE-326 (inadequate key length) are both in play when a project stores plaintext or uses AES-128: attackers who exfiltrate the database file get immediately usable cardholder data. NIST SP 800-111 and PCI-DSS 4.0 Req-3.5 require AES-256 or stronger because shorter keys are vulnerable to brute-force as compute costs fall. A single exposed plaintext column is enough to trigger breach notification obligations and PCI fines.

Switch to AES-256-GCM for all sensitive fields in src/lib/encryption.ts or src/utils/crypto.ts. Prefer authenticated encryption (GCM mode) over CBC to also detect tampering. Use the Node.js built-in crypto module — do not add a third-party wrapper for this:

import crypto from 'node:crypto';

const ALGO = 'aes-256-gcm';

export function encryptField(plaintext: string, key: Buffer): string {
  const iv = crypto.randomBytes(12);
  const cipher = crypto.createCipheriv(ALGO, key, iv);
  const encrypted = Buffer.concat([cipher.update(plaintext, 'utf8'), cipher.final()]);
  const tag = cipher.getAuthTag();
  return [iv.toString('hex'), tag.toString('hex'), encrypted.toString('hex')].join(':');
}

For database-level coverage, enable TDE on your provider (AWS RDS, Supabase) — that covers all columns, including ones you haven't explicitly wrapped. Both approaches together satisfy NIST SC-28 and PCI-DSS 4.0 Req-3.5.