SSL (Secure Sockets Layer) is a protocol that ensures communication security. In cryptography today it is one of the most popular protocols, the security of the connection in which is achieved due to the "layered environment". How does it work?
Instructions
Step 1
SSL sits between two protocols: the client program protocol (HTTP, FTP, Telnet, and so on) and the TCP / IP protocol for transporting packets.
SSL itself is divided into two layers: Handshake Protocol Layer (connection confirmation layer) and Record Layer (recording layer). In this case, the connection confirmation layer, in turn, is divided into three protocols: Handshake Protocol (connection confirmation), Change Cipher Spec Protocol (change of cipher parameters) and Alert Protocol (warning).
Step 2
The following diagram illustrates the layers of the SSL protocol:
Handshake Protocol Layer
As mentioned earlier, this layer contains three protocols:
Handshake Protocol
This protocol is used to negotiate session data between client and server. In this case, the following information is transmitted:
1. ID number of the session;
2. Certificates of the parties;
3. Parameters of the used cryptographic algorithm;
4. Used compression algorithm;
5. Information used to create keys, or a public key.
Change Cipher Spec Protocol
This protocol is used to change the data of the key used to encrypt data between the client and the server.
Alert Protocol
A warning message indicates a change in status or an error. In this case, both parties are notified.
Step 3
To ensure security, namely to verify the authenticity of the participants in the exchange of information, a certificate (X.509 standard) is used in the confirmation protocol. In cryptography, a certificate is a digital document that confirms the correspondence between a public key and information that identifies the owner of the key. The certificate is issued by a certification authority - a third party that is a priori trusted by the parties directly involved in the transfer of information.
Step 4
There are two main encryption methods used in cryptography: symmetric and asymmetric (public key) encryption. SSL uses both methods.
When using a symmetric key, both parties use the same key to encrypt data, this is a prerequisite in order to ensure the security of information transfer. This type of encryption is used to process large amounts of data.
Asymmetric encryption uses two keys obtained through a series of mathematical calculations. SSL uses asymmetric encryption to allow the server to verify the identity of the client and vice versa.
