Re: [GNU Crypto] Small problem with HMac

[Raif S. Naffah]

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hello Casey,

On Friday 10 January 2003 18:29, Casey Marshall wrote:
> Raif S. Naffah wrote:
> | On Thursday 09 January 2003 23:22, Casey Marshall wrote:
> |>...
> Going through the test case attached, I also noticed that HMac also
> doesn't handle keys larger than the block size properly...

this is because section 3 in rfc-2104 reads:

"
3. Keys

   The key for HMAC can be of any length (keys longer than B bytes are
   first hashed using H).  However, less than L bytes is strongly
   discouraged as it would decrease the security strength of the
   function.  Keys longer than L bytes are acceptable but the extra
   length would not significantly increase the function strength. (A
   longer key may be advisable if the randomness of the key is
   considered weak.)
"

i'd rather err on the side of caution.  dont you agree?


cheers;
rsn
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