Block cipher

Type of cipher / From Wikipedia, the free encyclopedia

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In cryptography, a block cipher is a deterministic algorithm operating on fixed-length groups of bits, called blocks. Block ciphers are specified elementary components in the design of many cryptographic protocols and are widely used to encrypt large amounts of data, including in data exchange protocols. A block cipher uses blocks as an unvarying transformation.

Even a secure block cipher is suitable for the encryption of only a single block of data at a time, using a fixed key. A multitude of modes of operation has been designed to allow their repeated use in a secure way to achieve the security goals of confidentiality and authenticity. However, block ciphers may also feature as building blocks in other cryptographic protocols, such as universal hash functions and pseudorandom number generators.