In computer science, the integrity check value (ICV) is a checksum or message footprint that allows an information technology system to detect changes or errors in data, thus ensuring data integrity. One-way hash functions are used to calculate the ICV as part of the error-checking process. Popular hash functions are 128-bit MD5 (Message Digest 5) and 160-bit SHA-1(Secure Hash Algorithm). ICV are used in HMAC (Hash Message Authentication Code) algorithms. In this case, the size of HMAC output is the same as that of the underlying hash function (128 or 160 bits in the case of MD5 and SHA-1), although it can be truncated if desired. Computer science, or computing science, is the study of the theoretical foundations of information and computation and their implementation and application in computer systems. ... A checksum is a form of redundancy check, a very simple measure for protecting the integrity of data by detecting errors in data that is sent through space (telecommunications) or time (storage). ... Information technology (IT), as defined by the Information Technology Association of America (ITAA)is: the study, design, development, implementation, support or management of computer-based information systems, particularly software applications and computer hardware. ... In general, data consist of propositions that reflect reality. ... In computer science and telecommunications, the term data integrity has the following meanings: The condition in which data is identically maintained during any operation, such as transfer, storage, and retrieval. ... A hash function [1] is a reproducible method of turning some kind of data into a (relatively) small number that may serve as a digital fingerprint of the data. ... A hash function [1] is a reproducible method of turning some kind of data into a (relatively) small number that may serve as a digital fingerprint of the data. ... In cryptography, MD5 (Message-Digest algorithm 5) is a widely used cryptographic hash function with a 128-bit hash value. ... The SHA (Secure Hash Algorithm) family is a set of related cryptographic hash functions designed by the National Security Agency (NSA) and published by the National Institute of Standards and Technology (NIST). ... A keyed-hash message authentication code, or HMAC, is a type of message authentication code (MAC) calculated using a cryptographic hash function in combination with a secret key. ... In mathematics, computing, linguistics, and related disciplines, an algorithm is a finite set of well-defined instructions for accomplishing some task which, given an initial state, will terminate in a defined end-state. ...