Description

This detector identifies WebCrypto API usage with insufficiently short authentication tags in TypeScript code. Short authentication tags in cryptographic operations can be vulnerable to brute-force attacks, compromising data integrity and authenticity guarantees.

Detection Strategy

• The detector analyzes TypeScript source code for WebCrypto API calls

• It specifically examines cryptographic operations that use authentication tags (like AES-GCM or ChaCha20-Poly1305)

• A vulnerability is reported when the authentication tag length is configured to be shorter than cryptographically secure recommendations

• The detector flags cases where tag lengths are set below industry standard minimums (typically less than 96 bits for GCM mode)

• It examines method calls and their parameters to identify insecure tag length configurations in encryption/decryption operations

Vulnerable code example

async function encryptData(key: CryptoKey, iv: Uint8Array, data: Uint8Array): Promise<ArrayBuffer> {
  // VULNERABLE: tagLength 64 bits is below the 96-bit minimum for AES-GCM
  return crypto.subtle.encrypt({ name: 'AES-GCM', iv, tagLength: 64 }, key, data);
}

✅ Secure code example

async function encryptData(key: CryptoKey, iv: Uint8Array, data: Uint8Array): Promise<ArrayBuffer> {
  // SAFE: tagLength is 128 bits (default), above the 96-bit minimum for AES-GCM
  return crypto.subtle.encrypt({ name: 'AES-GCM', iv, tagLength: 128 }, key, data);
}