Which of the following is not true of hash functions?

Hash functions help detect forgeries by computing a checksum of a message and then combining it with a cryptographic function so that the result is tamperproof.

The hashes produced by a specific hash function may vary in size.

A hash is a checksum designed so that no one can forge a message in a way that will result in the same hash as a legitimate message.

The output from the message digest algorithm $($MD$5)$ or the Secure Hash Algorithm $($SHA$)$ hash provides input for an asymmetric key algorithm that uses a private key as input.