AskDefine | Define decryption

Dictionary Definition

decryption n : the activity of making clear or converting from code into plain text; "a secret key or password is required for decryption" [syn: decoding, decipherment]

User Contributed Dictionary



Verbal noun of decrypt from de- + crypt (only attested in compounds, such as cryptogram) from κρυπτός.


  1. The process reversing an encryption, i.e. the process which converts encrypted data into its original form.


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Extensive Definition

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.


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 be mistranslated to "inter" (bury) and "disinter".


  • Helen Fouché Gaines, “Cryptanalysis”, 1939, Dover. ISBN 0-486-20097-3
  • 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
decryption in Arabic: تشفير
decryption in Bosnian: Enkripcija
decryption in Danish: Kryptering
decryption in German: Verschlüsselung
decryption in Estonian: Šifreerimine
decryption in Spanish: Criptografía
decryption in Esperanto: Ĉifrado
decryption in French: Chiffrement
decryption in Indonesian: Enkripsi
decryption in Icelandic: Dulkóðun
decryption in Malay (macrolanguage): Penyulitan
decryption in Dutch: Encryptie
decryption in Japanese: 暗号
decryption in Polish: Szyfr
decryption in Russian: Шифрование
decryption in Simple English: Encryption
decryption in Swedish: Kryptering
decryption in Thai: การเข้ารหัส
decryption in Vietnamese: Mã hóa
decryption in Ukrainian: Дешифрування
decryption in Chinese: 加密
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