SSL protocol stack
The SSL protocol stack includes the following protocols:
SSL record protocol at the lower layer.
SSL handshake protocol, SSL change cipher spec protocol, and SSL alert protocol at the upper layer.
Figure 121: SSL protocol stack
The following describes the major functions of SSL protocols:
SSL record protocol—Fragments data received from the upper layer, computes and adds MAC to the data, and encrypts the data.
SSL handshake protocol—Negotiates the cipher suite used for secure communication, authenticates the server and client, and securely exchanges the keys between the server and client. The cipher suite that needs to be negotiated includes the symmetric encryption algorithm, key exchange algorithm, and MAC algorithm.
SSL change cipher spec protocol—Notifies the receiver that subsequent packets are to be protected based on the negotiated cipher suite and key.
SSL alert protocol—Sends alert messages to the receiving party. An alert message contains the alert severity level and a description.