Cryptography

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Encryption technologies can be used on data to (1) hide their information content, (2) prevent their undetected modification, and (3) prevent their unauthorized use. When properly implemented, encryption technologies can provide assurance regarding the confidentiality, integrity, or origin of information that has been exchanged. It can also provide a method by which the authenticity of a document can be confirmed.

Several levels of cryptographic technology are currently in use. Cryptographic modules implement algorithms that form the building blocks of cryptographic applications. Using these modules, technologies are available that can be used to encrypt message transmissions so that eavesdroppers cannot determine the contents of the message. Digital signature technologies use cryptography to [authenticate the sender of a message. Hash technologies use cryptography to provide assurance to a message recipient that the contents of the message have not been altered. Several cryptographic technologies are used to ensure the confidentiality and integrity of data as it is being transmitted over the network. These technologies include digital certificates, digital signatures, secure sockets layer (SSL), and virtual private networks (VPN). Many of these technologies are built into applications that are commonly available on many computer systems. For example, most Web browsers support SSL for secure communications between a computer and the Web server.