Chapter 8 - Cryptography Exam Questions with Answers.

Chapter 8 - Cryptography Exam Questions with Answers Cryptology - Correct Answers: science of encryption: combines cryptography and cryptanalysis. Encryption - Correct Answers: The process of converting an original message into a form that is unreadable by unauthorized individuals. Cryptography - Correct Answers: process of making and using codes to secure transmission of info. Cryptanalysis - Correct Answers: process of obtaining original message from encrypted message without knowing algorithms. Decryption - Correct Answers: the process of converting the ciphertext message back into plaintext so it can be readily understood. Key - Correct Answers: - the information used in conjunction with an algorithm to create the ciphertext from the plaintext or derive the plaintext from the ciphertext. - this can be a series of bits used by a computer program, or it can be a passphrase used by humans. Algorithm - Correct Answers: - A set of steps or mathematical calculations used in solving a problem - In cryptography, it is the programmatic steps used to convert an unencrypted message into an encrypted sequence of bits that represent the message, or the programs that enable the cryptographic processes. Foundations of Cryptology: - Correct Answers: - cryptology has a long and multicultural history With emergence of technology; need for ______________ in information technology environment greatly increased. - Correct Answers: encryption All popular web browsers use built-in encryption features for __________ e-commerce applications. - Correct Answers: secure Plaintext can be encrypted through two methods: - Correct Answers: 1. bit stream 2. block cipher Bit Stream Method: - Correct Answers: each bit in the plaintext is transformed into a cipher bit one bit at a time. Block Cipher Method: - Correct Answers: the message is divided into blocks, and then each block of plaintext bits is transformed into an encrypted block of cipher bits using an algorithm and key. Substitution Cipher - Correct Answers: - substitute one value for another Monoalphabetic substitution: - Correct Answers: uses only one alphabet Polyalphabetic substitution: - Correct Answers: more advanced; uses two or more alphabets. Vigenère cipher - Correct Answers: advanced cipher type that uses simple polyalphabetic code; made up of 26 distinct cipher alphabets. Transposition cipher - Correct Answers: - easy to understand, but if properly used, produces ciphertext that is difficult to decipher. - rearranges values within a block to create ciphertext - to make the encryption even stronger, the keys and block sizes can be made much larger. Transportation cipher can be done at the _____ level or at the byte (character) level. - Correct Answers: bit Exclusive OR - Correct Answers: a function of Boolean algebra ; two bits are compared If two bits are identical , the result is binary _____. - Correct Answers: 0 If two bits are not identical, result is binary ____. - Correct Answers: 1 XOR ___________ is a very simple symmetric cipher that is used in many applications where security is NOT a defined requirement. - Correct Answers: encryption What company developed the Vernam Cipher - Correct Answers: AT&T Vernam Cipher - Correct Answers: - uses set of characters once per encryption process In ________ cipher, each character of the plaintext is turned into a number, and a pad value for that position is added. - Correct Answers: Vernam Book or Running Key Cipher - Correct Answers: - uses text in book as key to decrypt a message. Ciphertext contains codes representing page, line, and ________ ______________. - Correct Answers: word numbers Algorithm is the mechanical process of : - Correct Answers: - looking up references from the ciphertext - converting each reference to a word by using the cipher texts value and the key. What are the typical sources in "Book or Running Key Cipher" ? - Correct Answers: - thesaurus - dictionaries Hash Functions: - Correct Answers: - mathematical algorithms that generate message summary/digest to confirm message identity and confirm no context has changed. - use of keys not required Hash Algorithms: - Correct Answers: publicly known functions that create hash value. Cryptographic Algorithms are often grouped into two broad categories: - Correct Answers: - symmetric and asymmetric. Todays popular cryptosystems use a ______ combo of symmetric and asymmetric algorithms. - Correct Answers: hybrid Symmetric and asymmetric algorithms are distinguished by the types of ______ they use for encryption and decryption operations. - Correct Answers: keys Symmetric Encryption - Correct Answers: uses same "secret key" to encipher and decipher message. In Symmetric Encryption, the encryption methods are extremely _____________, requiring minimal processing. - Correct Answers: efficient In symmetric encryption, both the sender and _____________ must possess encryption key. - Correct Answers: receiver In symmetric encryption, if either copy of key is compromised, an ________________ can decrypt and read messages. - Correct Answers: intermediate Asymmetric Encryption is also known as: - Correct Answers: public-key encryption Asymmetric encryption uses two different but __________ keys. Either key can encrypt or decrypt the message. - Correct Answers: related When using ciphers, ______ of crypto variable or key is very important. - Correct Answers: size Strength of many encryption applications and cryptosystems are measured by ______ size. - Correct Answers: key For ____________, security of encrypted data is not dependent on keeping encrypting algorithm secret. - Correct Answers: cryptosystems Cryptosystems security depends on: - Correct Answers: keeping some or all of elements of cryptovariables or keys secret.