ISC Exam Questions

what is this called?

If different keys generate the same ciphertext for the same message, what is this called?

A.
Collision

B.
Secure hashing

C.
MAC

D.
Key clustering

Explanation:
Message A was encrypted with key A and the result is ciphertext Y. If
that same Message A was encrypted with key B the result should not be ciphertext Y.
The ciphertext should be different since a different key was used. But if this does
take place it is referred to as key clustering.