2

I remember I read that a MAC can be considered as a PRF.

Can a variable-length input keyed-PRF be considered as a MAC?

otus
  • 32,132
  • 5
  • 70
  • 165
Dingo13
  • 2,867
  • 3
  • 27
  • 46
  • 6
    I'd note that the first statement is incorrect: a secure MAC is not necessarily a secure PRF. Consider any secure MAC and add a single zero bit in the end. The result is clearly not random, but equally secure as a MAC. – Dmitry Khovratovich Jul 03 '14 at 12:49

1 Answers1

3

Usually. $\:$ A variable-length input keyed-PRF is a [PRF's output length]-bit MAC.
In particular, a variable-length input keyed-PRF with long output is automatically a MAC.