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.
Correct Answer: A
IDEA https://en.wikipedia.org/wiki/International_Data_Encryption_Algorithm In cryptography, the International Data Encryption Algorithm (IDEA), originally called Improved Proposed Encryption Standard (IPES), is a symmetric-key block cipher designed by James Massey of ETH Zurich and Xuejia Lai and was first described in 1991. The algorithm was intended as a replacement for the Data Encryption Standard (DES). IDEA is a minor revision of an earlier cipher Proposed Encryption Standard (PES). The cipher was designed under a research contract with the Hasler Foundation, which became part of Ascom-Tech AG. The cipher was patented in a number of countries but was freely available for non-commercial use. The name "IDEA" is also a trademark. The last patents expired in 2012, and IDEA is now patent-free and thus completely free for all uses. IDEA was used in Pretty Good Privacy (PGP) v2.0 and was incorporated after the original cipher used in v1.0, BassOmatic, was found to be insecure. IDEA is an optional algorithm in the OpenPGP standard. Incorrect answers: CAST - symmetric algorithm. Created in 1996 by Carlisle Adams and Stafford Tavares. Operates on 64 bit blocks and has a key size of 40-128 bits. Typically used in GPG and PGP. Encryption is either 12 or 16 rounds. DES - The Data Encryption Standard is a symmetric-key algorithm for the encryption of digital data. Although its short key length of 56 bits makes it too insecure for applications, it has been highly influential in the advancement of cryptography. RSA - a public-key cryptosystem that is widely used for secure data transmission. It is also one of the oldest. The acronym RSA comes from the surnames of Ron Rivest, Adi Shamir, and Leonard Adleman, who publicly described the algorithm in 1977
Question 12
Which algorithm implements an unbalanced Feistel cipher?
Correct Answer: A
Skipjack https://en.wikipedia.org/wiki/Skipjack_(cipher) Skipjack uses an 80-bit key to encrypt or decrypt 64-bit data blocks. It is an unbalanced Feistel network with 32 rounds.
Question 13
What is a "Collision attack" in cryptography?
Correct Answer: D
Collision attacks try to find two inputs producing the same https://en.wikipedia.org/wiki/Collision_attack A collision attack on a cryptographic hash tries to find two inputs producing the same hash value, i.e. a hash collision. This is in contrast to a preimage attack where a specific target hash value is specified.
Question 14
The ATBASH cipher is best described as what type of cipher?
Correct Answer: C
Substitution https://en.wikipedia.org/wiki/Atbash Atbash is a monoalphabetic substitution cipher originally used to encrypt the Hebrew alphabet. It can be modified for use with any known writing system with a standard collating order.
Question 15
Which of the following is a fundamental principle of cryptography that holds that the algorithm can be publicly disclosed without damaging security?
Correct Answer: C
Kerkchoff's principle https://en.wikipedia.org/wiki/Kerckhoffs%27s_principle Kerckhoffs's principle (also called Kerckhoffs's desideratum, assumption, axiom, doctrine or law) of cryptography was stated by Netherlands born cryptographer Auguste Kerckhoffs in the 19th century: A cryptosystem should be secure even if everything about the system, except the key, is public knowledge. Kerckhoffs's principle was reformulated (or possibly independently formulated) by American mathematician Claude Shannon as "the enemy knows the system", i.e., "one ought to design systems under the assumption that the enemy will immediately gain full familiarity with them". In that form, it is called Shannon's maxim. This concept is widely embraced by cryptographers, in contrast to "security through obscurity", which is not.
