What option provides the most secure salting solution for hashing?

Generating a unique salt for each hashed entry is the most secure salting solution for hashing because it significantly enhances security by ensuring that even identical passwords will produce different hash values. This practice helps to mitigate the risk of precomputed attacks, such as rainbow table attacks, since an attacker cannot leverage precomputed hashes for a specific salt. Each password being hashed with its own unique salt means that even if two users have the same password, their hash outputs will differ, making it more difficult for attackers to guess or crack passwords through hash comparison.

Using the same salt for multiple hashes can create vulnerabilities as it allows attackers to exploit those commonalities, undermining the benefits of salting. A pre-defined salt would also be insecure because it would be predictable and could be easily discovered by potential attackers. Employing a complex password as a salt does not add significant protection either, as the primary role of a salt is to be unique and random rather than complex; using a strong, unique salt is far more advantageous in improving security.