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CISSP - Cryptography Exam Questions And Answers
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CISSP - Cryptography Exam Questions And AnswersWhat is cryptanalysis used for?
A. Its strength depends on the algorithm being used
B. Increasing substitution functions in a cryptographic algorithm
C. Decreasing transposition functions in a cryptographic algorithm
D. To determine the permutations used - Answer A. Cryptanalysis is the attempt to
reverse-engineer a cryptosystem, perhaps for the purpose of finding out what key was
used. When this key is discovered, then all the other messages that were encrypted with
this key will also be accessed. Cryptanalysis is done by the white hats in order to test
the robustness of the algorithm.
Successful brute force attacks are becoming more frequent due to
A. The use of permutations and transpositions are more in algorithms.
B. Stronger the algorithm lesser will be its complexity hence easier to be attacked.
C. Processor speed and power has increased.
D. Key length decreases with time. -Answer C. A Brute force attack is resource
intensive. It tries all values until the correct value is hit. Since computers keep getting
additional processors, the attacker can have much more powerful Brute force attacks.
What of the following is not a property or characteristic of a one-way hash function?
A. It takes a message of arbitrary length and generates a fixed-length value from this.
B. Given the value of the digest, it should be computationally infeasible to find the
message actually represented.
C. It must not be possible, or very rare, that two different messages generate the same
digest.
D. It changes a fixed length message to an arbitrary length value. -Answer D. A hashing
algorithm takes a string of variable length, the message can be of any size and
computes a fixed-length value. The fixed-length value is the message digest. The MD
family creates the fixed-length value of 128 bits and SHA creates one of 160 bits.
, What would be proof that a message has been changed?
A. The public key has been altered.
B. The private key has been altered.
C. The message digest has been altered
D. The message has been encrypted correctly. -Answer C. Hashing algorithms produce
message digests as a means to determine whether tampering has occurred. Both
originator and recipient generate their own digests independently. The recipient
compares these values. If they are different, the recipient knowsthe message has been
tampered with.
Which of the following is an algorithm developed by the U.S. Federal government to
produce secure message digests?
A. Data Encryption Algorithm
B. Digital Signature Standard
C. Secure Hash Algorithm
D. Data Signature Algorithm - Answer C. SHA was designed to produce secure message
digests. Digital Signature Standard, or DSS, the standard to generate digital signatures
mandates the use of SHA. DSS also specifies the digital signature algorithms that may
be used along with SHA: RSA, DSA and ECDSA.
What would be the best description of the difference between HMAC and CBC-MAC?
A. HMAC generates a message digest and is used to achieve integrity; CBC-MAC uses
the block cipher to encrypt blocks of data to achieve confidentiality.
B. HMAC uses a symmetric key and a hashing algorithm; CBC-MAC uses the first block
for the checksum.
C. HMAC: Integrity and data origin authentication; CBC-MAC: The block cipher used in
the process of creating a MAC.
D. HMAC encrypts a message with a symmetric key and then puts the result through a
hashing algorithm; CBC-MAC encrypts the whole message. - C. During an HMAC
operation, a message is concatenated to a symmetric key and the result put through a
hashing algorithm. The process provides integrity and system or data authentication.
CBC-MAC uses a block cipher to create a MAC,
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