[Cryptography] Literature on reusing same key for AES / HMAC?

[ianG]

On 4/11/2015 19:09 pm, Will Sargent wrote:
> I know people are busy, and any response at all will be useful,
> especially if it can point me to the correct search terms or papers to
> back this up.  If the answer is "no-one's looked, but it can't be good"
> then that's fine too.



1.  I doubt anyone would study such a thing because it's obscure.  But 
this would change if there was a big popular system using it.

2.  I'd be staggered if there was a connection.  Eg an attack as brash 
as that would speak to huge problems - probably in both algorithms.

3.  In contrast, I'd say, just don't do that.  At a minimum take the one 
key and expand it into two keys.  Or exchange more material, really in 
this day and age, key material is cheap.  (OK, so I suspect you're 
reviewing an actual system...)



iang