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.

Section: Mixed questions
Explanation:
Some products installed on systems can also watch for input values that might result in buffer overflows, but the best countermeasure is proper programming. This means use bounds checking. If an input value is only sup-posed to be nine characters, then the application should only accept nine characters and no more.
Some languages are more susceptible to buffer overflows than others, so programmers should understand these issues, use the right languages for the right purposes, and carry out code review to identify buffer overflow vulnerabilities.

Token Ring was designed to be a more fault-tolerant topology than Ethernet, and can be a very resilient topology when properly implemented.
Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the
Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 72.

Degaussing is recommended as the best method for purging most
magnetic mediA. Degaussing is a process whereby the magnetic
media is erased, i.e., returned to its initial virgin statE. Erasure via degaussing may be accomplished in two ways:
In AC erasure, the media is degaussed by applying an alternating
field that is reduced in amplitude over time from an initial high
value (i.e., AC-powered)
In DC erasure, the media is saturated by applying a unidirectional
field (i.e., DC-powered or by employing a permanent magnet)
Another point about degaussing: Degaussed magnetic hard drives
will generally require restoration of factory-installed timing tracks,
so data purging is recommendeD. Also, physical destruction of
CDROM or WORM media is required.
*Answer " Overwriting the media with new application data" is not recommended because the application may not completely overwrite the old data properly, and strict configuration controls must be in place on both the operating system and the software itselF. Also, bad sectors on the media may not permit the software to overwrite old data properly. To satisfy the DoD clearing
requirement, it is sufficient to write any character to all data locations in question (purging).
To purge the media, the DoD requires overwriting with a pattern,
then its complement, and finally with another pattern; e.g., overwrite
first with 0011 0101, followed by 1100 1010, then 1001 0111. The number of times an overwrite must be accomplished depends on the storage media, sometimes on its sensitivity, and sometimes on differing DoD
component requirements, but seven times is often recommended.
*Answer "Applying a concentration of hydriodic acid (55% to 58% solution) to the gamma ferric oxide disk surface" is a rarely used method of media destruction, and acid solutions should be used in a well-ventilated area only by qualified personnel.
*Answer "Making sure the disk is re-circulated as quickly as possible to prevent object reuse" is wrong. Source: NCSC-TG-025 A Guide to Understanding
Data Remanence in Automated Information Systems.

The answer: "Elliptic Curve Cryptography (ECC)". This type of cryptography is
based on the complex mathematics of elliptic curves. These algorithms are advantageous for their
speed and strength.
The other answers are not correct because:
"Rivest, Shamir, Adleman (RSA)" is incorrect because RSA is a "traditional" asymmetric algorithm.
While it is reasonably strong, it is not considered to be as strong as ECC based systems.
"El Gamal" is incorrect because it is also a "traditional" asymmetric algorithm and not considered as strong as ECC based systems.
"Advanced Encryption Standard (AES)" is incorrect because the question asks specifically about asymmetric algorithms and AES is a symmetric algorithm.
References: Official ISC2 Guide page: 258 All in One Third Edition page: 638 The RSA Crypto FAQ: http://www.rsa.com/rsalabs/node.asp?id=2241