RE: [CISSP-D] Symmetric Key and authentication.

Hi,

IMHO and understanding, any form of encryption can be used for
Authentication (i.e. sender identification), provided you are able to use an
enc/dec method that's; 
1. not easy to duplicate by a malicious third-party
2. maintains the value of the message content for the relevant time
3. easy to communicate, securely, to the receiving party

All the above parameters (and others that I haven't mentioned) are easier
and much simpler to achieve practically with Asymmetric encryption rather
than Symmetric encryption and hence the definition by Shon Harris!

Regards,
Roshan Mani

-----Original Message-----
From: CISSP-Discuss@yahoogroups.com [mailto:CISSP-Discuss@yahoogroups.com]
On Behalf Of Vijay Kumar
Sent: 05 May 2005 10:11
To: CISSP-Discuss@yahoogroups.com
Subject: [CISSP-D] Symmetric Key and authentication.

One of the books I read gave example of how symmetric encryption can be used
for authenticating to another entity with whom you have a shared secret. 
 
Yet, the Shon Harris books says that symmetric encryption only provided
Confidentiality and integrity but not auth and non repudiation.
 
Who is right?
 
Thanks





 
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