I'm trying to solve this question related to one-time pads and perfect secrecy:
My solution is: I assumed that the current message space is $M = \left\{ 0,1 \right\}^l$ and the new keyspace after removing $0^l$ from the set is $K = \left\{ 0,1 \right\}^l - 0^l$. Since clearly $|K| < |M|$, the new scheme is not perfectly secret.
Is my solution correct?