Describe the feature

sealSession() and unsealSession() spread iron-webcrypto's defaults object without overriding the iteration count. The defaults specify iterations: 1 for both encryption and integrity key derivation.

When generateKey() is called with a string password, it performs PBKDF2-SHA1 key derivation using this iteration count. Current OWASP guidance (2023) recommends a minimum of 600,000 PBKDF2-SHA1 iterations for password-derived keys.

The sealed token format exposes the HMAC salt and digest, providing the material needed for offline brute-force of the session password. Benchmarked speeds show ~4,102 attempts/sec with iterations=1 vs ~5.27 attempts/sec with iterations=600000 — a ~677x difference.

Suggested change

Override iron-webcrypto's defaults in sealSession/unsealSession to use at minimum 600,000 PBKDF2 iterations, e.g.:

const sealDefaults = {
  ...ironDefaults,
  encryption: { ...ironDefaults.encryption, iterations: 600_000 },
  integrity: { ...ironDefaults.integrity, iterations: 600_000 },
}

Alternatively, consider switching to a stronger KDF like Argon2 or scrypt.

Workaround

Applications can explicitly configure higher iterations today via useSession() config:

useSession(event, {
  password: 'my-secret',
  seal: {
    encryption: { iterations: 600_000 },
    integrity: { iterations: 600_000 },
  },
})

This option is currently undocumented.