[Cisspstudy] cisspstudy - Cryptography questions

[twitwicki at hannaford.com]

Hello all,
      I'd like your thoughts on these questions from Michael Gregg's CISSP
Practice questions:

In an asymmetric system how many keys are required for 10 users to fully
communicate?

A. 10
B. 20
C. 45
D 110

The answer states D. 110 -  "Each user would have his private, phus his
public key, plus each of the nine other public keys"
Shouldn't the answer be B. 20  because the public keys is only couned once
for each private/public pair?  This also seems consistent with the formula
for symmetric keys: N(N-1)/2 where N is the number of users needing to
communicate.  In this case the secret key is only counted once even if it's
shared between users.


Here's another question that has me puzzled:

Which cryptographic system can be used for integrity, authenticity and
non-repudiation?

A. Asymmetric encryption
B. Symmetric  encryption
C. Hashing
D. None of the above

The answers states A. Asymmetric.  Shouldn't the answer be D. None of the
above because Hashing is needed for integrity?

Your thoughts will be much appreciated.


Tom Witwicki, CIPP
Director, Information Security
Hannaford Bros. Co.
207-885-2073

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