WGU C839 - Intro to Cryptography Exam 2022 completely Solved 100 Q&A GRADED A+

The most widely used asymmetric encryption algorithm is what? A RSA B Vigenere C DES D Caesar Cipher - Answer A Original, unencrypted information is referred to as ____. A text B plaintext C cleantext D ciphertext - Answer B Which of the following is NOT an asymmetric system? A PGP B RSA C SSL D DES - Answer D In order for User A to send User B an encrypted message that only User B can read, User A must encrypt message with which of the following keys? A User A's public key B User A's private key C User B's public key D User B's private key - Answer C The greatest weakness with symmetric algorithms is _____. A They are less secure than asymmetric B The problem of key exchange C They are slower than asymmetric D The problem of generating keys - Answer B Which of the following is generally true about block sizes? A Smaller block sizes increase security B Block sizes must be more than 256 bits to be secure C Block size is irrelevant to security D Larger block sizes increase security - Answer D A _____ is a function that takes a variable-size input m and returns a fixed-size string. A Symmetric cipher B Hash C Asymmetric cipher D Feistel - Answer B Which of the following is a cryptographic protocol that allows two parties to establish a shared key over an insecure channel? A Elliptic Curve B RSA C MD5 D Diffie-Hellman - Answer D A _________ is a digital representation of information that identifies you as a relevant entity by a trusted third party? A Digital Signature B Hash C Ownership stamp D Digest - Answer A What is the standard used by most digital certificates? A X.509 B CRL C RFC 2298 D OCSP - Answer A DES uses keys of what size? A 56 bits B 192 bits C 128 bits D 64 bits - Answer A Which of the following is NOT a key size used by AES? A 512 bits B 128 bits C 192 bits D 256 bits - Answer A Which of the following was a multi alphabet cipher widely used from the 16th century (1553) to the early 20th century (1900s)? A Vigenere B Caesar C Atbash D Scytale - Answer A Which of the following is a substitution cipher used by ancient Hebrew scholars? A Caesar B Vigenere C Scytale D Atbash - Answer D Shifting each letter in the alphabet a fixed number of spaces to the right or left is an example of what? A Bit shifting B Confusion C Multi substitution D Single substitution - Answer D Which of the following most accurately defines encryption? A changing a message so it can only be easily read by the intended recipient B Making binary changes to a message to conceal it C changing a message using complex mathematics D Applying keys to plain text - Answer A If you use substitution alone, what weakness is present in the resulting cipher text? A It is the same length as the original text B It is easily broken with modern computers. C It is too simple. D Because it maintains letter and word frequency. - Answer D _____ uses at least two different shifts, changing the shift with different letters in the plain text. A Atbash B multi-alphabet encryption C Scytale D Caesar cipher - Answer B ____ was designed to provide built in cryptography for the clipper chip. A Blowfish B Skipjack C GOST D 3DES - Answer B Which of the following uses an 80 bit key on 64 bit blocks? A Twofish B AES C Skipjack D DES - Answer C With _____, the message is divided into blocks and each block is encrypted separately. This is the most basic mode for symmetric encryption. A Electronic codebook (ECB) B Cipher-block chaining (CBC) C Cipher feedback (CFB) D Output feedback (OFB) - Answer A Which of the following is an example of an unbalanced Feistel? A 3DES B Skipjack C Twofish D AES - Answer B This process is done by having each block of plaintext is XORed with the previous ciphertext block before being encrypted. A Output feedback (OFB) B Cipher-block chaining (CBC) C Electronic codebook (ECB) D Cipher feedback (CFB) - Answer B The process wherein the ciphertext block is encrypted then the ciphertext produced is XOR'd back with the plaintext to produce the current ciphertext block is called what? A Output feedback (OFB) B Cipher-block chaining (CBC) C Cipher feedback (CFB) D Electronic codebook (ECB) - Answer C This is a method for turning a block cipher into a stream cipher by generating a keystream block, which are then XORed with the plaintext blocks to get the ciphertext. A Cipher feedback (CFB) B Electronic codebook (ECB) C Output feedback (OFB) D Cipher-block chaining (CBC) - Answer C Which of the following modes can be used to turn a block cipher into a stream cipher? A Propagating cipher-block chaining (PCBC) and Electronic codebook (ECB) B Counter Mode (CTR) and Propagating cipher-block chaining (PCBC) C Electronic codebook (ECB) and Output feedback (OFB) D Output feedback (OFB) and Counter Mode (CTR) - Answer D A fixed-size pseudorandom number that is fed into a symmetric cipher to increase randomness is called what? A IV B Key C Chain D Salt - Answer A A number that is used only one time then discarded is called what? A Nonce B Chain C Salt D IV - Answer A Which of the following is a stream cipher that uses variable length key from 1 to 256 bytes? A RC4 B AES C DESx D DES - Answer A This algorithm was published by the German engineering firm Seimans in 1993. It is a software based stream cipher using Lagged Fibonacci generator along with a concept borrowed from the shrinking generator ciphers. A RC4 B Blowfish C FISH D Twofish - Answer C Which of the following is NOT required for a hash? A Minimum key length of 256 bits B Variable-length input, fixed-length output C Non-reversible D Few collisions - Answer A A ______ refers to a situation where two different inputs yield the same output. A Substitution B Convergence C Collision D Transposition - Answer C What is a salt? A Key rotation B Random bits intermixed with a hash to increase randomness and reduce collisions. C Random bits intermixed with a symmetric cipher to increase randomness and make it more secure. D Key whitening - Answer B RFC 1321 describes what hash? A RIPEMD B SHA1 C GOST D MD5 - Answer D What size block does FORK256 use? A 256 B 128 C 512 D 64 - Answer C In 1977 researchers at MIT described what asymmetric algorithm? A RSA B AES C DH D EC - Answer A What is the formula (M^e)(%n) related to? A Encrypting with EC B Generating Mersenne primes