QUESTION: 5

Juanita has been assigned the task of selecting email encryption for the staff of the insurance company she works for. The various employees often use diverse email clients. Which of the following methods is available as an add-in for most email clients?

Caesar cipher
RSA
PGP
DES

Answer(s): C

Explanation:

PGP https://en.wikipedia.org/wiki/Pretty_Good_Privacy
Pretty Good Privacy (PGP) is an encryption program that provides cryptographic privacy and authentication for data communication. PGP is used for signing, encrypting, and decrypting texts, e- mails, files, directories, and whole disk partitions and to increase the security of e-mail communications. Phil Zimmermann developed PGP in 1991.

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QUESTION: 6

What is a salt?

Key whitening
Random bits intermixed with a symmetric cipher to increase randomness and make it more secure
Key rotation
Random bits intermixed with a hash to increase randomness and reduce collisions

Answer(s): D

Explanation:

Random bits intermixed with a hash to increase randomness and reduce collisions https://en.wikipedia.org/wiki/Salt_(cryptography)
Salt is random data that is used as an additional input to a one-way function that hashes data, a password or passphrase. Salts are used to safeguard passwords in storage. Historically a password was stored in plaintext on a system, but over time additional safeguards were developed to protect a user's password against being read from the system. A salt is one of those methods.

Incorrect answers:
Key whitening - a technique used to increase the security of block ciphers. It consists of steps that combine the data with portions of the key (most commonly using a simple XOR) before the first round and after the last round of encryption.
Key rotation - is when you retire an encryption key and replace that old key by generating a new cryptographic key. Rotating keys on a regular basis help meet industry standards and cryptographic best practices.
Random bits intermixed with a symmetric cipher to increase randomness and make it more secure – Initialization Vector (IV)

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QUESTION: 7

Which of the following was a multi alphabet cipher widely used from the 16th century to the early 20th century?

Atbash
Caesar
Scytale
Vigenere

Answer(s): D

Explanation:

Vigenere https://en.wikipedia.org/wiki/Vigen%C3%A8re_cipher
The Vigenère cipher is a method of encrypting alphabetic text by using a series of interwoven Caesar ciphers, based on the letters of a keyword. It employs a form of polyalphabetic substitution.
First described by Giovan Battista Bellaso in 1553, the cipher is easy to understand and implement, but it resisted all attempts to break it until 1863, three centuries later. This earned it the description le chiffre indéchiffrable (French for 'the indecipherable cipher'). Many people have tried to implement encryption schemes that are essentially Vigenère ciphers. In 1863, Friedrich Kasiski was the first to publish a general method of deciphering Vigenère ciphers.

Incorrect answers:
Caesar - Monoalphabetic cipher where letters are shifted one or more letters in either direction. The method is named after Julius Caesar, who used it in his private correspondence.
Atbash - Single substitution monoalphabetic cipher that substitutes each letter with its reverse (a and z, b and y, etc).
Scytale - Transposition cipher. A staff with papyrus or letter wrapped around it so edges would line up. There would be a stream of characters which would show you your message. When unwound it would be a random string of characters. Would need an identical size staff on other end for other individuals to decode message.

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QUESTION: 8

A symmetric Stream Cipher published by the German engineering firm Seimans in 1993. A software based stream cipher that uses a Lagged Fibonacci generator along with concepts borrowed from shrinking generator ciphers.

DESX
FISH
Twofish
IDEA

Answer(s): B

Explanation:

FISH https://en.wikipedia.org/wiki/FISH_(cipher)
The FISH (FIbonacci SHrinking) stream cipher is a fast software based stream cipher using Lagged Fibonacci generators, plus a concept from the shrinking generator cipher. It was published by Siemens in 1993. FISH is quite fast in software and has a huge key length. However, in the same paper where he proposed Pike, Ross Anderson showed that FISH can be broken with just a few thousand bits of known plaintext.

Incorrect answers:
Twofish - symmetric algorithm. Designed by Bruce Schneier, John Kelsey, Doug Whiting, David Wagner, Chris Hall, and Niels Ferguson. Uses a block size of 128 bits and key sizes of 128, 192, or 256 bits. It is a Feistel cipher.
IDEA - symmetric algorithm. Designed by James Massey and Xuejia Lai. Operates on 64 bit blocks and has a 128 bit key. Consists of 8 identical transformations each round and an output transformation.
DESX - symmetric algorithm. 64 bit key is appended to data, XOR it, and then apply the DES algorithm.

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