Encryption is a privacy scheme to convert plain text into a non-readable form, called cypher-text, which cannot be understood by the unauthorized users. When the intended user converts the message to its original plain text form to make it understandable, that mechanism is called decryption. With the advent of Internet and widespread usage of online marketing, net banking, health care and other services, where business critical information are shared, everyone is much more aware of the application of encryption methodology.
In case of a connection to a secure server, the text gets encrypted automatically in the web browsers. However, many people prefer to use encryption in the email correspondence as well. The programs featuring plug-ins for email-clients help to accomplish this. PGP (Pretty Good Privacy) is the best among them. PGP helps not only in email message encryption, but the personal files and folders can also be encrypted using this methodology. Likewise, it is also possible to apply encryption to an entire drive or volume. A special decryption key is used to mount the drive for the access purpose. After the drive-read it can be dismounted and thus it returns to the encrypted state, so that Spywares, interlopers, snoops or Trojan horses cannot access it. Generally financial programs or other sensitive data of an organization are stored in encrypted drives.
As it is easier to tap wireless circuits, for wireless communications encryption or decryption is specially preferred. Nevertheless, for any kind of sensitive transaction encryption/decryption should be used, such as online purchase through credit card or sharing of organizational secrets between different departments.
There are basically two categories of the encryption methodology symmetric and asymmetric. In a symmetric key algorithm a predetermined single key is shared between the client and server to both encrypt and decrypt texts. Blowfish, DES and AES are the examples of symmetric key algorithm. On the other hand, asymmetric key algorithm uses a key pair, a public and a private key. Public keys are used to encrypt the text, but the cypher-text can only be decrypted by the receiver, who own the private key of the key pair. Diffie-Hellman and RSA are the examples of asymmetric key algorithm. Asymmetric encryption is stronger than the symmetric encryption, because of the privacy of the decryption key. But it might not be very secure, until the recipient of the data or the server is correctly identified. In this regard, digital signatures are usually used online to authenticate the receiver.
As more people get exposed to the fact of the open nature of Internet, instant messaging and email, the need of encryption will undoubtedly be realized. Without encryption the Information, that is passed through Internet, is not only available to everyone, but is also open to be misused.