I agree with Doug. I have found many contradictions in several of the books
I've read and I've had to spend a lot of time finding the right answer. To
find the right answer: GO TO THE SOURCE. The source would be the NIST docs,
the Common Criteria, the ISO 17799, the BS7799, etc (quick link:
http://www.cccure.org/modules.php?name=Downloads&d_op=viewdownload&cid=67 )
Yes,more reading, more time spent, but at least you'll get a solid
foundation and understanding of the principles that you need for the exam.
Rand
On 5/20/05, Doug Landoll <dlandoll@veridyn.com> wrote:
Be careful this is a bad approach to preparing for the CISSP exam.
The CISSP prep books out there are a great tool for CISSP candidates
and the books consolidate a lot of information. However, they are
not free of errors. Do not rely on an answer just because it is in a
book.
Symmetric encryption can provide authentication but only to the
other party in the transaction. i.e., if you and I share a key and i
receive a message encrypted in that key, then I KNOW it came from
you. However, I cannot take that message and show it to someone else
and convince them that the message came from you (since either you
OR I could have encrypted it.)
This second type of authentication is called non-repudiation and can
only be performed through asymetric encryption.
Note: Not all asymetric encryption can enforce non-repudiation. For
example, Diffie-Hellman algorithm was designed for key exchange only
and does not provide non-repudiation. (It was the El Gamal algorithm
that extended D-H to provide non-repudiation.
--- In CISSP-Discuss@yahoogroups.com, Vijay Kumar <vijaychhipa@y...>
wrote:
Manish
Your comments are in-line with what is logical. However the Shon
Harris
book mentioned that authentication can not be had with Symmetric
only encryption.
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--
----------------------
Rand
~~~~~~~~~~~
Four wheels move the body. Two wheels move the soul.
