> Or does each check need its own set of iterations? This is exactly what a password-key derivation function is. Each check is an independent process involving

> Or does each check need its own set of iterations? This is exactly what a password-key derivation function is. Each check is an independent process involving the unique salt stored in cleartext. Normally (OWASP recommendations) each password check is about 310,000 iterations of SHA256, or a more complex construction like Argon2. The problem here is that LastPass had 5000 iterations of SHA256 for a lot of accounts, and some accounts mysteriously have even lower iteration counts.