data encryption, the process of disguising information as “ciphertext,” ordata unintelligible to an unauthorized person. Conversely,decryption, or decipherment, is the process of converting ciphertext back into its original format. Manual encryption has been used since Roman times, but the term has become associated with the disguising of information via electronic computers. Encryption is a process basic tocryptology.

Computers encrypt data by applying analgorithm—i.e., a set of procedures or instructions for performing a specified task—to a block of data. A personal encryptionkey, or name, known only to the transmitter of the message and its intended receiver, is used to control the algorithm’s encryption of the data, thus yielding unique ciphertext that can be decrypted only by using the key.

Since the late 1970s, two types of encryption have emerged. Conventionalsymmetric encryption requires the same key for both encryption and decryption. A common symmetric encryption system is theAdvanced Encryption Standard (AES), an extremely complexalgorithm approved as a standard by theU.S. National Institute of Standards and Technology.Asymmetric encryption, or public-key cryptography, requires a pair of keys; one for encryption and one for decryption. It allows disguised data to be transferred between allied parties at different locations without also having to transfer the (not encrypted) key. A common asymmetric encryption standard is theRSA (Rivest-Shamir-Adleman) algorithm.

Britannica Quiz

Codes, Secrets, and Ciphers Quiz

Encryption keys selected at random and of sufficient length are considered almost impregnable. A key 10 characters long selected from the 256 availableASCII characters could take roughly 40 billion centuries to decode, assuming that the perpetrator was attempting 10,000 different keys per second.