Encryption

	Email		Print
	Bookmark		Link

Encryption

In cryptography

Cryptography

Cryptography is the practice and study of hiding information. In modern times cryptography is considered a branch of both mathematics and computer science and is affiliated closely with information theory, computer security and engineering....
, encryption is the process of transforming information

Information

Information as a Conveyed concept has a diversity of meanings, from everyday usage to technical settings. Generally speaking, the concept of information is closely related to notions of constraint, communication, control system, data, form, instruction, knowledge, Meaning , stimulation, pattern, perception, and knowledge representation....
(referred to as plaintext

Plaintext

In cryptography, plaintext is the information which the sender wishes to transmit to the receiver. Before the computer era, plaintext simply meant text in the language of the communicating parties....
) using an algorithm (called cipher

Cipher

In cryptography, a cipher is an algorithm for performing encryption and decryption — a series of well-defined steps that can be followed as a procedure....
) to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key

Key (cryptography)

In cryptography, a key is a piece of information that determines the functional output of a cryptographic algorithm or cipher. Without a key, the algorithm would have no result....
. 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.

Discussion

Ask a question about 'Encryption'

Start a new discussion about 'Encryption'

Answer questions from other users

Full Discussion Forum

Encyclopedia

In cryptography

Cryptography

Information

Plaintext

Cipher

Key (cryptography)

Encryption software

Encryption software is software whose main task is encryption and decryption of data, usually in the form of files on hard drives and removable media, email messages, or in the form of packets sent over computer networks....
” 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 computer

Computer

A computer is a machine that manipulates Data according to a list of Code .The first devices that resemble modern computers date to the mid-20th century , although the computer concept and various machines similar to computers existed earlier....
s, storage devices (e.g. USB flash drives), network

Computer network

A computer network is a group of interconnected computers. Networks may be classified according to a wide variety of characteristics. This article provides a general overview of some types and categories and also presents the basic components of a network....
s (e.g. the Internet

Internet

The Internet is a global network of interconnected computers, enabling users to share information along multiple channels. Typically, a computer that connects to the Internet can access information from a vast array of available server and other computers by moving information from them to the computer's local memory....
, e-commerce), mobile telephones, wireless microphone

Wireless microphone

A wireless microphone, as the name implies, is a microphone without a physical cable connecting it directly to the sound recording or amplifying equipment with which it is associated....
s, wireless intercom

Wireless intercom

A wireless intercom is an electronic device that enables voice communication without the need to run wires between intercom stations. A wired intercom system may incorporate wireless elements....
systems, Bluetooth

Bluetooth

Bluetooth is a wireless protocol for exchanging data over short distances from fixed and mobile devices, creating personal area networks . It was originally conceived as a wireless alternative to RS232 data cables....
devices and bank automatic teller machines. Encryption is also used in digital rights management

Digital rights management

Digital rights management refers to access control technologies used by publishers, copyright holders, and hardware manufacturers to limit usage of digital media or devices....
to prevent unauthorized use or reproduction of copyrighted material and in software also to protect against reverse engineering

Reverse engineering

Reverse engineering is the process of discovering the technological principles of a device, object or system through analysis of its structure, function and operation....
(see also copy protection

Copy protection

Copy protection, also known as content protection, copy prevention, or copy restriction, is a technology for preventing the reproduction of copyrighted software, movies, music, and other media....
).

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

Message authentication code

A cryptography message authentication code is a short piece of information used to authenticate a message.A MAC algorithm accepts as input a secret key and an arbitrary-length message to be authenticated, and outputs a MAC ....
(MAC) or a digital signature

Digital signature

A digital signature or digital signature scheme is a type of asymmetric key algorithm. For messages sent through an insecure channel, a properly implemented digital signature gives the receiver reason to believe the message was sent by the claimed sender....
. 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

Traffic analysis

Traffic analysis is the process of intercepting and examining messages in order to deduce information from patterns in communication. It can be performed even when the messages are encrypted and cannot be cryptanalysis....
, TEMPEST

TEMPEST

TEMPEST is a codename referring to investigations and studies of compromising emanations . Compromising emanations are defined as unintentional Intelligence -bearing signals which, if intercepted and analyzed, may disclose the information transmitted, received, handled, or otherwise processed by any information-processing equipment....
, or Trojan horse

Trojan horse (computing)

The Trojan horse, also known as trojan, in the context of computer software, describes a class of computer threats that appears to perform a desirable function but in fact performs undisclosed malicious functions that allow unauthorized access to the host machine, giving them the ability to save their files on the user's computer...
.

One of the earliest public key encryption applications was called Pretty Good Privacy

Pretty Good Privacy

Pretty Good Privacy is a computer program that provides cryptographic privacy and authentication. PGP is often used for signing, encrypting and decrypting e-mails to increase the security of e-mail communications....
(PGP), according to Paul Rubens. It was written in 1991 by Phil Zimmermann and was bought by Network Associates in 1997 and is now called PGP Corporation.

There are a number of reasons why an encryption product may not be suitable in all cases. First e-mail must be digitally signed at the point it was created to provide non-repudiation for some legal purposes, otherwise the sender could argue that it was tampered with after it left their computer but before it was encrypted at a gateway according to Paul. An encryption product may also not be practical when mobile users need to send e-mail from outside the corporate network.*

External links

Includes Cryptography list at metzdowd and SecurityFocus Crypto list.

Encryption

See also

External links