The CAis used in public key cryptography, not secret key cryptography. A CA will certify that a public key actually belongs to a specific individual and that the information associated with the individual's key is valid and correct. The CA accomplishes this certification by digitally signing the individual's public key and associated information. The certification professes to another person who wants to send a message to this individual using public key encryption that the public key actually belongs to the intended individual. The Consultation Committee, International Telephone and Telegraph, International Telecommunications Union (CCITT-ITU)/ International Organization for Standardization (ISO) X.509 Authentication framework defines a format for public key certificates. This structure is outlined in Figure.

Answer "A networked group of m users with separate keys for each pair of
users will require m (m-1)/2 keys" is an important issue in secret key cryptography; therefore it is
not the correct answer. If, among a network of m users, each user
wants to have secure communications with every other user on the network,
then there must be a secret key for each pair of potential users.
This concept can be illustrated with five users as shown in Figure.

Thus, with five users, the number of independent keys is equal to (5 x
4)/2 or 10 as depicted by the ten connecting lines in Figure A.6.
*answer "Secure distribution of the keys" is incorrect since securely distributing the keys to all
users is, obviously, a very important requirement.
Answer d is incorrect since a compromise of the keys can, indeed,
enable the attacker to impersonate the key owners and, therefore,
read and send false messages.

The following are incorrect answers because they are all suitable methods.
A Delta CRL is a CRL that only provides information about certificates whose statuses have changed since the issuance of a specific, previously issued CRL.
The Online Certificate Status Protocol (OCSP) is an Internet protocol used for obtaining the revocation status of an X.509 digital certificate.
A Distribution point CRL or CRL Distribution Point, a location specified in the CRL
Distribution Point (CRL DP) X.509, version 3, certificate extension when the certificate is issued.
References:
RFC 2459: Internet X.509 Public Key Infrastru
http://csrc.nist.gov/groups/ST/crypto_apps_infra/documents/sliding_window.pdf
http://www.ipswitch.eu/online_certificate_status_protocol_en.html
Computer Security Handbook By Seymour Bosworth, Arthur E. Hutt, Michel E. Kabay
http://books.google.com/books?id=rCx5OfSFUPkC&printsec=frontcover&dq=Computer+Se curity+Handbook#PRA6-PA4,M1

The CIA acronym stands for Confidentiality, Integrity and Availability.
"Confidentiality, Integrity and Entity (CIE)" is incorrect. "Entity" is not part of the
telecommunications domain definition.
"Confidentiality, Integrity and Authenticity (CIA)" is incorrect. While authenticity is included in the
telecommunications domain, CIA is the acronym for confidentiality, integrity and availability.
"Confidentiality, Integrity, and Liability (CIL)" is incorrect. Liability is not part of the
telecommunications domain definition.
References:
CBK, pp. 407 - 408

Explanation/Reference:
Explanation:
2 2
ISC code of Ethics does not refer to control. To follow the ISC code of Ethics you should act honorably, honestly, justly, responsibly, and legally, and protect society.
Incorrect Answers:
2
A: To follow the ISC code of Ethics you should act honestly.
2
B: To follow the ISC code of Ethics you should use ethical behavior as you should act honorably, honestly, justly, responsibly, and legally, and protect society.
2
C: To follow the ISC code of Ethics you should act legally.
References:
Harris, Shon, All In One CISSP Exam Guide, 6th Edition, McGraw-Hill, New York, 2013, p. 1062