   in cryptography, encryption is the process of encoding messages or information in such a way that only authorized parties can read it."encryption basics | eff surveillance self-defense project." encryption basics | eff surveillance self-defense project. surveillance self-defense project, n.d. web. 06 nov. 2013. . encryption does not of itself prevent interception, but denies the message content to the interceptor.goldreich, oded. foundations of cryptography: volume 2, basic applications. vol. 2. cambridge university press, 2004. in an encryption scheme, the message or information, referred to as plaintext, is encrypted using an encryption algorithm, generating ciphertext that can only be read if decrypted. for technical reasons, an encryption scheme usually uses a pseudo-random encryption key generated by an algorithm. it is in principle possible to decrypt the message without possessing the key, but, for a well-designed encryption scheme, large computational resources and skill are required. an authorised recipient can easily decrypt the message with the key provided by the originator to recipients, but not to unauthorised interceptors. ==kinds of encryption== === symmetric key encryption === in symmetric-key schemes,symmetric-key encryption software the encryption and decryption keys are the same. thus communicating parties must have the same key before they can achieve secret communication. === public key encryption ===  in public-key encryption schemes, the encryption key is published for anyone to use and encrypt messages. however, only the receiving party has access to the decryption key that enables messages to be read.bellare, mihir. "public-key encryption in a multi-user setting: security proofs and improvements." springer berlin heidelberg, 2000. page 1. public-key encryption was first described in a secret document in 1973; before then all encryption schemes were symmetric-key (also called private-key). a publicly available public key encryption application called pretty good privacy (pgp) was written in 1991 by phil zimmermann, and distributed free of charge with source code; it was purchased by symantec in 2010 and is regularly updated.{{cite web|url=http://www.computerworld.com/s/article/917612
Cryptography