Today, encryption is used to transmit sensitive digital data across computer networks or, increasingly, to keep sensitive computer files private while they remain stored on a desktop or laptop computer. The messages are changed from readable to unreadable and back again using complex mathematical algorithms known as keys.
Security experts expect to see more use of encryption for unclassified computer information.
Asymmetric encryption requires each person to have one publicly known key and one private key, both of them unique to that individual. To send an encrypted message, the sender must look up the recipient's publicly known key and use it to encrypt the message, which can then be read only if it is decrypted with the recipient's private key. No keys need change hands using this technique, although it is more time-consuming than symmetric encryption. Many solutions combine the two strategies, using the public key to encrypt a secret key, which is used to encrypt the actual message. The most popular asymmetric algorithms are from RSA Data Security Inc., although agencies, unless they apply for a waiver, are required to use the symmetric Digital Encryption Standard.