What property of a hash function makes reversing the hash algorithm mathematically infeasible?

• A. Collision resistance
• B. Preimage resistance
• C. Seed generation
• D. Verification

Answer: (B)

The property of a hash function that makes reversing the hash algorithm mathematically infeasible is preimage resistance. This characteristic means that given a hash value, it should be computationally impractical to find an input (or preimage) that produces that hash value. In other words, even if someone knows the output of the hash function, they should not be able to determine the original input that generated it.

Preimage resistance is essential for maintaining the security of hashed data, as it prevents attackers from easily discovering inputs to the hash function and thus protects sensitive information. This is particularly important in scenarios like password hashing, where an attacker encountering the hash should not be able to derive the original password.

Collision resistance, while important, relates to the difficulty of finding two different inputs that produce the same hash value, rather than the ability to reverse the hash to find the original input. Seed generation refers to producing initial values for algorithms, and verification pertains to the ability to confirm that a value corresponds to a given input, which does not inherently address the feasibility of reversing a hash.