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Re: AES, AES-MAC
>- I believe it is possible to use AES as
> a MAC algorithm a la DES-MAC. Has this
> been specified by NIST? Has it been specified
> by IETF how to use it in the context of IPsec?
>
>- I seem to remember talk about SHA-256/384/512.
> What are these and have their use been
> specified for IPsec? What is their relationship
> to AES-MAC?
The thread on SHA-256/384/512 can be found here:
http://www.vpnc.org/ietf-ipsec/mail-archive/msg00337.html
These are hash algorithms from NIST with 256/384/512 bits of output. From
the thread above I don't believe they are going to be a requirement for
IPsec because of their performance. AES-MAC was also discussed in this
thread. It's performance is roughly that of AES-CBC encryption/decryption.
However, there has been discussion of using a counter mode for AES
encryption/decryption rather than CBC mode to improve encryption/decryption
performance, so perhaps something other than a straight AES-MAC would be
needed for equivalent authentication performance. Please see the following
message, which contains the slides from Steve Kent's presentation that
discuss this:
http://www.vpnc.org/ietf-ipsec/mail-archive/msg00168.html
Best Regards,
Joseph D. Harwood
jharwood@vesta-corp.com
www.vesta-corp.com