Cryptographic Primitives Based On Symmetric Ciphers
Symmetric ciphers are often used to achieve other cryptographic primitives than just encryption.
Encrypting a message does not guarantee that this message is not changed while encrypted. Hence often a message authentication code is added to a ciphertext to ensure that changes to the ciphertext will be noted by the receiver. Message authentication codes can be constructed from symmetric ciphers (e.g. CBC-MAC).
However, symmetric ciphers also can be used for non-repudiation purposes. See the ISO 13888-2 standard.
Another application is to build hash functions from block ciphers. See one-way compression function for descriptions of several such methods.
Read more about this topic: Symmetric-key Algorithm
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