In cryptography, a block cipher is a deterministic algorithm operating on fixed-length groups of bits, called blocks. They are specified elementary components in the design of many cryptographic protocols and are widely used to implement the encryption of large amounts of data, including data exchange protocols.

What is a block cipher?

A block cipher encrypts data in blocks using a deterministic algorithm and a symmetric key. As in the case of stream ciphers, most encryption methods encrypt bits one by one (stream ciphers). Block ciphers, on the other hand, encrypt 128 bit blocks with a key of predetermined length: 128, 192, or 256 bits.

Why is block cipher used?

Block ciphers, if used properly, are an effective method for resisting adversarial attempts to read data, either data stored on disk or in transit on the network. A block cipher is one of the two common modern symmetric cipher types.