Most attacks on hash functions primarily involve A. Finding Collisions.
Collisions occur when two different inputs produce the same hash output, which can compromise the integrity of the hash function. While B. Pre-generating millions of hashes (known as a rainbow table attack) can be a technique to find a specific hash, it typically applies to situations like password cracking rather than direct attacks on the hash function itself. Option C. Really good random guessing is not a systematic or effective method for attacking hash functions, as hashing is designed to make this difficult.
So the correct answer focusing on the nature of attacks against hash functions would be A. Finding Collisions.
If looking at the options as combinations:
- A and B: could be seen as valid since B relates to specific usage in attacks like password recovery, but these don't directly attack the hash function design itself.
- A and C: not really effective since guessing isn't systematic.
- B and C: also not applicable.
Overall, the most relevant answer with respect to traditional attacks on hash functions would center on A, finding collisions.