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Glossary of Terms (page 1) adaptive-chosen-ciphertext - A version of the chosen-ciphertext attack where the cryptanalyst can choose ciphertexts dynamically. A Cryptanalyst can mount an attack of this type in a scenario in which he or she has free use of a piece of decryption hardware, but is unable to extract the decryption key from it. adaptive-chosen-plaintext - A special case of the chosen-plaintext attack in which the cryptanalyst is able to choose plaintexts dynamically, and alter his or her choices base on the results of previous encryptions. adversary - Commonly used to refer to the opponent, the enemy, or any other mischievous person that desires to compromise one's security. AES - The Advanced Encryption Standard that will replace DES (The Data Encryption Standard) around the turn of the century. algebraic attack - A method of cryptanalytic attack used against block ciphers that exhibit a significant amount of mathematical structure. algorithm - A series of steps used to complete a task. Alice - The name traditionally used for the first user of cryptography in a system: Bob's friend. ANSI - American National Standards Institute. API - Application Programming Interface. attack - Either a successful or unsuccessful attempt at breaking part or all of a cryptosystem. See algebraic attack, birthday attack, brute force attack, chosen ciphertext attack, chosen plaintext attack, differential cryptanalysis, known plaintext attack, linear cryptanalysis, middleperson attack. authentication - The action of verifying information such as identity, ownership or authorization. biometrics - The science of using biological properties to identify individuals; for example, fingerprints, retina scan and voice recognition. birthday attack - A brute-force attack used to find collisions. It gets its name from the surprising result that the probability of two or more people in a group of 23 sharing the same birthday is greater than 1/2. bit - A binary digit, either 1 or 0. blind signature scheme - Allows one party to have a second party sign a message without revealing any (or very little) information about the message to the second party. block - A sequence of bits of fixed length; longer sequences of bits can be broken down into blocks. block cipher - A symmetric cipher which encrypts a message by breaking it down into blocks and encrypting each block. block cipher based MAC - MAC that is preformed by using a block cipher as a keyed compression function. Bob - The name traditionally used for the second user of cryptography in a system; Alice's friend. boolean expression - A mathematical expression in which all variables involved are either 0 or 1; it evaluates to either 0 or 1. brute force attack - This attack requires trying all (or a large fraction of all) possible values till the right value is found; also called an exhaustive search. |