Introduction to TLS and SSL

October 21, 2008 Dovecot

TLS or Transport Layer Security is a protocol that is encrypted and is a close relative of SSL.  Actually TLS has developed from SSL and has backward compatibility.  SSL, Secure Sockets Layer, is a protocol or language that is used to encrypt communication between clients and servers. This type of communication is necessary when transporting sensitive information like credit card processing.   The OpenSSL project,  is an organization working to develop a cryptography library based on SSL v2/v3 and TLS v1.

What the Process of TLS or SSL Provides
1. TLS and SSL Provides – Authentication – the SSL server authentication allows a user to verify the server identity. The use of public-key cryptology allows a client to verify that the server has a valid certificate and public ID and that it has been issued a certificate of authority (CA). The client can hold a list of trusted CAs.
2. TLS  and SSL Provides Verification of the User - the user is verified in the process in the same way as the server and using the same methods as the server verification.
3. TLS and SSL Provides Encryption – the entire communication between the client and the server is encrypted.

Installation of TLS or SSL Communication
At times it is important to encrypt the communication between the server and the client in order to protect the data that is being transferred. SSL, Secure Socket Layer ins enabled on Apache using the mod_ssl module. Once SSL has been enabled on Apache secure communication will occur over port 443 using the https:// in the browser.   Note this is encrypted communication based on the 443 port where TLS is encrypted communication based on port 993.  The focus at this point is creating encryption for Dovecot so the TLS application will be described not the implementation of SSL for port 443.

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