[Cryptography] Perfect Integrity?

[Peter Fairbrother]

On 01/08/18 12:51, Alexandre Anzala-Yamajako wrote:
> The short answer is : yes.
> You can find some examples here 
> https://crypto.stackexchange.com/questions/43659/information-theoretic-message-authentication-code-mac
> I believe that any Wegman-Carter MAC where the key is changed after 
> every use gives you information theoretic security.

A one-bit W-C MAC will give an attacker no advantage in guessing the bit 
- but he will still have a 50% chance of guessing right.

For information-theoretic security the MAC has to be as long as the 
message. I think.



Peter Fairbrother