Which type of algorithm provides the highest level of protection against brute-force attacks?

PFS (Perfect Forward Secrecy) is a property of key agreement protocols that ensures the compromise of a long-term key does not compromise past session keys; it is not a hashing algorithm used to protect against brute-force password cracking directly.

HMAC (Hash-based Message Authentication Code) provides data integrity and authentication using a cryptographic hash function and a secret key, but it relies on an underlying hash function (like SHA or MD5) and is not itself a standalone algorithm for protecting against brute-force password attacks.

MD5 (Message-Digest Algorithm 5) is a cryptographic hash function that is now considered insecure due to known vulnerabilities, making it susceptible to collision attacks and less resistant to brute-force attacks than SHA algorithms.

SHA (Secure Hash Algorithm), particularly later versions like SHA-256 or SHA-512, produces much longer and more computationally intensive hashes than MD5. This significantly increases the time and resources required for brute-force attacks and makes collision attacks practically infeasible, offering a high level of cryptographic security.