What is often a sign of a broken hashing algorithm?

A sign of a broken hashing algorithm is primarily indicated by preimage collisions. A hashing algorithm is considered secure if it is computationally infeasible to reverse the hashing process to find the original input from its output (the hash). A preimage collision occurs when two different inputs produce the same hash value, thereby allowing an attacker to potentially generate a hash value for a different input, which can compromise the integrity and security of the data being protected.

If a hashing algorithm exhibits preimage collisions, it means the fundamental property of one-wayness has been compromised. This property is essential for ensuring that even if an attacker knows the hash output, they cannot easily derive the original input. The existence of preimage collisions suggests that the algorithm might be weak against certain attacks, leading to vulnerabilities in systems relying on it for security, such as password storage or data integrity verification.

Other options may highlight issues in security, but they do not specifically indicate the fundamental flaws that are characteristic of a hashing algorithm. For instance, hash duplication may occur but can be a result of benign factors like similar inputs, while unpredictable key generation relates more to encryption rather than hashing. Inconsistent encryption pertains to issues with encryption algorithms rather than hashing. Thus, preimage collision is indeed the correct indicator