Introduction to Cryptography - C839- 172 QUESTIONS_ WITH COMPLETE SOLUTIONS

- Cipher - Key - Algorithm CORRECT ANSWERS: - The algorithm(s) needed to encrypt and decrypt a message. - The random bits used in encrypting a message. - The mathematical process used to alter a message and read it unintelligible by any but the intended party Stream Cipher CORRECT ANSWERS: Uses a keystream generator and encrypts a message one bit at a time, usually implemented in hardware. Popular when data comes in long streams (such as with older wireless networks or cell phones). Attack Tree CORRECT ANSWERS: A branching, hierarchical data structure that represents a set of potential techniques for exploiting security vulnerabilities Defense in Depth CORRECT ANSWERS: A defense that uses multiple types of security devices to protect a network. Also called layered security. Threat analysis/assessment CORRECT ANSWERS: An evaluation of the type, scope, and nature of events or actions that can result in adverse consequences; identification of the threats that exist against enterprise assets. It usually defines the level of threat and the likelihood of it materializing. Cryptography CORRECT ANSWERS: The science of altering communication so that it cannot be understood without having the key - Substituting one character of cipher text for each character of plain text - Caesar Cipher: Every letter is shifted a fixed number of spaces to the left or the right in the alphabet; single alphabet substitution - Atbash Cipher: Hebrew code which reverses the alphabet - Affine Cipher: Single-substitution; converts a letter to a number, passes it through a mathematical function of ax + b (mod M), and then converts it back to a letter - Rot13 Cipher: All characters are rotated 13 spaces through the alphabet; basically the Caesar cipher using a +13 shift CORRECT ANSWERS: - What is mono-alphabet substitution? - What are four examples of this method? - Plaintext - Ciphertext CORRECT ANSWERS: - Normal text that has not been encrypted - Text which has been encrypted through an algorithm and key Scytale CORRECT ANSWERS: A tool used to perform a transposi