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Security on the Internet

Appendix: Public Key Encryption, SSL and VPNs

Secure Socket Layer encryption (SSL) uses public key encryption to send information from your browser to the host computer. It is a low-level encryption scheme used to encrypt transactions in higher-level protocols such as HTTP and FTP. SSL includes provisions for server authentication, encryption of data in transit, and optional client authentication.

Encryption works by encoding the text of a message with a key. In traditional encryption systems, the same key is used for both encoding and decoding. In public key encryption, two keys are used: one for encoding and another for decoding. In this system everyone owns a unique pair of keys. One of the keys, called the public key, is widely distributed and used for encoding messages. The other key, called the private key, is a closely held secret used to decrypt incoming messages. A person who needs to send a message to a second person can encrypt the message with that person's public key. The message can only be decrypted by the owner of the secret private key, making it safe from interception. This system can also be used to create unforgeable digital signatures.

Secure Virtual Private Networks (SVPNs) allow organisations to send confidential information over the Internet, confident that it will travel safely unseen, unchanged, un-copied and intact. Secure VPNs provide this security through the implementation of authentication, access control, public key encryption and data integrity checks.

Last Updated: 14^th January 2002