Encryption

"Encrypt" redirects here. For the film, see Encrypt (film).

This article is about algorithms for encryption and decryption. For an overview of cryptographic technology in general, see Cryptography.

In cryptography, encryption is the process of transforming information (referred to as plaintext) using an algorithm (called cipher) to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key. The result of the process is encrypted information (in cryptography, referred to as ciphertext). In many contexts, the word encryption also implicitly refers to the reverse process, decryption (e.g. “software for encryption” can typically also perform decryption), to make the encrypted information readable again (i.e. to make it unencrypted).

Encryption has long been used by militaries and governments to facilitate secret communication. Encryption is now used in protecting information within many kinds of civilian systems, such as computers, networks (e.g. the Internet e-commerce), mobile telephones, wireless microphones, wireless intercom systems, Bluetooth devices and bank automatic teller machines. Encryption is also used in digital rights management to prevent unauthorized use or reproduction of copyrighted material and in software also to protect against reverse engineering (see also copy protection).

Encryption, by itself, can protect the confidentiality of messages, but other techniques are still needed to protect the integrity and authenticity of a message; for example, verification of a message authentication code (MAC) or a digital signature. Standards and cryptographic software and hardware to perform encryption are widely available, but successfully using encryption to ensure security may be a challenging problem. A single slip-up in system design or execution can allow successful attacks. Sometimes an adversary can obtain unencrypted information without directly undoing the encryption. See, e.g., traffic analysis, TEMPEST, or Trojan horse.

Semantics

This term is somewhat a misnomer, but is very commonly used as described above. More correctly, the term "encyphering" should be used (along with "decyphering" for decoding a cryptographically encoded message, when you know the cipher and key). "Decrypt" actually means to decode a message when you do not know the cypher and/or key (i.e., codebreaking), and "encrypt" is meaningless, strictly speaking. However, the common usage is so pervasive even in academic literature, that these distinctions are now generally lost.

The terms "encrypt" and "decrypt" are discouraged in international documents, since they tend to translate to "inter" (bury) and "disinter".

References

• Helen Fouché Gaines, “Cryptanalysis”, 1939, Dover. ISBN 0-486-20097-3
• Ibrahim A. Al-Kadi, “The origins of cryptology: The Arab contributions”, Cryptologia, 16(2) (April 1992) pp. 97–126.
• Ibrahim A. Al-Kadi, “Cryptography and Data Security: Cryptographic Properties of Arabic”, proceedings of the Third Saudi Engineering Conference. Riyadh, Saudi Arabia: Nov 24-27, Vol 2:910-921., 1991.
• David Kahn, The Codebreakers - The Story of Secret Writing (ISBN 0-684-83130-9) (1967)
• Abraham Sinkov, Elementary Cryptanalysis: A Mathematical Approach, Mathematical Association of America, 1966. ISBN 0-88385-622-0

See also

• Cryptography - term which encompasses encryption and other concepts used for hiding information
• Encryption software
• Cipher - algorithm used for encryption
• Key - special knowledge needed for successful decryption

External links

• SecurityDocs Resource for encryption whitepapers
• Accumulative archive of various cryptography mailing lists. Includes Cryptography list at metzdowd and SecurityFocus Crypto list.
• WebApplet Try out more than 20 encryption and hash algorithms
• Encrypt and decrypt private messages online