Construction of Response-Authenticator

Michael Lecuyer mjl at
Sun Sep 12 19:52:20 CEST 2010

No one here is going to do your homework for you.

RFC 2865 is pretty clear on how this is calculated.

A Message-Authenticator attribute in the response attributes will 
require more work. Perhaps you can get extra credit for figuring it out.

On 2010-09-12 1:25 PM, Theresa Otte wrote:
> Hello,
> I use FreeRADIUS 2.1.8 on Ubuntu 10.4. For my course at university I
> have to write a program in which I need to re-calculate the
> response-authenticator
> (MD5(Code+ID+Length+Request-Auth.+Attributes+Secret)). Does anybody know
> how FreeRADIUS calculates it? Does it take the binary code of the
> message fields or an other encoding? When I try to re-calculate it, I
> never get the same Response-Authenticator as in the Access-Accept-Message.
> I'm programming with Python and using the libraries of scapy and
> hashlib. Perhaps anyone of you can help me.
> Thank you very much!
> -
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