Enhanced Password Protection in SQL Server 2025

SQL Server 2025 significantly improves how SQL logins and contained database users store and handle passwords. Instead of storing simple hashes, Microsoft now uses a Password-Based Key Derivation Function (PBKDF) a cryptographic function that makes it computationally expensive to guess or crack passwords.

Password-Based Key Derivation Function (PBKDF)-

A PBKDF is a function that:

* Takes a password and a cryptographic salt.

* Applies a hashing algorithm repeatedly (e.g., 100,000 times).

* Produces a derived key or hash, which is securely stored.

Note - The goal of multiple iterations is to slow down brute-force attacks. Even if an attacker gets access to password hashes, trying millions of combinations becomes expensive and time-consuming.

What’s new in SQL Server 2025?

* SQL Server 2025 uses a PBKDF algorithm, similar to PBKDF2 (though Microsoft hasn’t explicitly named it).

* The password is hashed with 100,000 iterations, which dramatically increases the time required to guess a password through brute-force methods.

Conceptual Process: Hash = PBKDF2(password, salt, 100,000 iterations)

Security Benefits:

* Brute-force resistant: 100,000 iterations make cracking attempts extremely slow.

* Resilient to data breaches: Even if hashes are stolen, they are not easily reversed.

*Salt usage: Prevents precomputed attacks.

* Standard compliant: Follows NIST best practices for federal-level security.

Example Scenario (Conceptual) -

Suppose a hacker steals the password hash for a user:

* Old method: A simple SHA1 or SHA2 hash may be cracked in seconds or minutes using a GPU.

* New method (PBKDF): 100,000 iterations of a secure hash + salt make each guess take, say, 200ms this would take years to crack strong passwords even with modern hardware.