Introduction to Secure Socket Layer

Secure Socket Layer  was originated by Netscape. Version 3 of the protocol was designed with public review and input from industry and was published as an Internet draft document. Subsequently, when a consensus was reached to submit the protocol for Internet standardization, the TLS working group was formed within IETF to develop a common standard. The current work on TLS is aimed at producing an initial version as an Internet Standard. This first version of TLS can be viewed as essentially an SSLv3.1 and is very close to and backward compatible with SSLv3.
The bulk of this section is devoted to a discussion of SSLv3. At the end of the section, the key differences between SSLv3 and TLS are described.
SSL Architecture

SSL is designed to make use of TCP to provide a reliable end-to-end secure service. SSL is not a single protocol but rather two layers of protocols, as illustrated in above Figure.
The SSL Record Protocol provides basic security services to various higher-layer protocols. In particular, the hypertext transfer protocol (HTTP), which provides the transfer service for Web client/server interaction, can operate on top of SSL. Three higher-layer protocols are defined as part of SSL: the Handshake Protocol, the Change Cipher Spec Protocol, and the Alert Protocol. These SSL-specific protocols are used in the management of SSL exchanges and are examined later in this section.
Two important SSL concepts are the SSL session and the SSL connection, which are defined in the specification as follows:
Connection: A connection is a transport (in the OSI layering model definition) that provides a suitable type of service. For SSL, such connections are peer-to-peer relationships. The connections are transient. Every connection is associated with one session.
Session: An SSL session is an association between a client and a server. Sessions are created by the Handshake Protocol. Sessions define a set of cryptographic security parameters, which can be shared among multiple connections. Sessions are used to avoid the expensive negotiation of new security parameters for each connection.