212-81 exam

A cryptanalysis success where the attacker discovers additional plain texts (or cipher texts) not previously known.A . Total Break B. Distinguishing Algorithm C. Instance Deduction D. Information DeductionView AnswerAnswer: C Explanation: Instance Deduction https://en.wikipedia.org/wiki/Cryptanalysis The results of cryptanalysis can also vary in usefulness. For example, cryptographer Lars Knudsen (1998) classified...

In a Feistel cipher, the two halves of the block are swapped in each round . What does this provide?A . Diffusion B. Confusion C. Avalanche D. SubstitutionView AnswerAnswer: B Explanation: Confusion https://en.wikipedia.org/wiki/Confusion_and_diffusion#Definition Confusion means that each binary digit (bit) of the ciphertext should depend on several parts of the...

What does the OCSP protocol provide?A . Revoked certificates B. Hashing C. VPN connectivity D. EncryptionView AnswerAnswer: A Explanation: Revoked certificates https://en.wikipedia.org/wiki/Online_Certificate_Status_Protocol The Online Certificate Status Protocol (OCSP) is an Internet protocol used for obtaining the revocation status of an X.509 digital certificate.It is described in RFC 6960 and is...

Which of the following would be the fastest.A . EC B. DH C. RSA D. AESView AnswerAnswer: D Explanation: AES https://en.wikipedia.org/wiki/Symmetric-key_algorithm AES - symmetric cipher. Symmetric keys use the same key for both encryption and decryption. Both the sender and receiver of the data must know and share the secret...

Which of the following is the standard for digital certificates?A . RFC 2298 B. X.509 C. CRL D. CAView AnswerAnswer: B Explanation: X.509 https://en.wikipedia.org/wiki/X.509 X.509 is a standard defining the format of public key certificates. X.509 certificates are used in many Internet protocols, including TLS/SSL, which is the basis for...

What best describes the shifting of each letter a fixed number of spaces to the left or right?A . Single substitution B. Multi substitution C. XOR D. Bit shiftingView AnswerAnswer: A Explanation: Single substitution https://en.wikipedia.org/wiki/Substitution_cipher#Simple_substitution Substitution of single letters separately―simple substitution―can be demonstrated by writing out the alphabet in some...

Which one of the following are characteristics of a hash function? (Choose two)A . Requires a key B. One-way C. Fixed length output D. Symmetric E. FastView AnswerAnswer: B,C Explanation: Correct answers: One-way, Fixed length output https://en.wikipedia.org/wiki/Cryptographic_hash_function A cryptographic hash function is a mathematical algorithm that maps data of arbitrary...

Which of the following is required for a hash?A . Not vulnerable to a brute force attack B. Few collisions C. Must use SALT D. Not reversible E. Variable length input, fixed length output F. Minimum key lengthView AnswerAnswer: D,E Explanation: Correct answers: Variable length input, fixed length output and...

The Clipper chip is notable in the history of cryptography for many reasons. First, it was designed for civilian used secure phones. Secondly, it was designed to use a very specific symmetric cipher . Which one of the following was originally designed to provide built-in cryptography for the Clipper chip?A...

What is the basis for the FISH algorithm?A . The Lagged Fibonacci generator B. Prime number theory C. Equations that describe an ellipse D. The difficulty in factoring numbersView AnswerAnswer: A Explanation: The Lagged Fibonacci generator https://en.wikipedia.org/wiki/FISH_(cipher) The FISH (FIbonacci SHrinking) stream cipher is a fast software based stream cipher...