Encryption

Encryption is the transformation of data into a form, unreadable by anyone without a secret decryption key. Its purpose is to ensure privacy by keeping the information hidden from anyone for whom it is not intended, even those who can see the encrypted data. For example, one may wish to encrypt files on a hard disk to prevent an intruder from reading them.

In a multi-user setting, encryption allows secure communication over an insecure channel. In a symmetric cryptosystem, a single key serves as both the encryption and decryption keys.

Modern encryption algorithms play a vital role in the security assurance of IT systems and communications as they can provide not only confidentiality, but also the following key elements of security:

• Authentication: the origin of a message can be verified.

• Integrity: proof that the contents of a message have not been changed since it was sent.

• Non-repudiation: the sender of a message cannot deny sending the message.

The primary purpose of encryption is to protect the confidentiality of digital data stored on computer systems or transmitted via the Internet or other computer networks.