Data encryption is the process of transforming data (referred to as plaintext) to make it unreadable except to those possessing some secret knowledge, usually referred to as a key. The result of the process is encrypted data (referred to as ciphertext). Data encryption aims at preserving confidentiality of messages. The reverse process of deriving the plaintext from the ciphertext (using the key) is known as decryption. A cipher is a pair of algorithms which perform encryption and decryption. The study of data encryption is part of cryptography. The study of how to break ciphers, i.e., to obtaining the meaning of encrypted information without access to the key, is called cryptanalysis.
Encryption has been used to protect communications since ancient times by militaries and governments to facilitate secret communication. The earliest known usages of cryptography include a tool called Scytale, which was used by the Greeks as...
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