Programming new SSL applications

There is a series of tasks that you must complete to create SSL applications.

Creating the TCP connection
When you want to program an SSL application, create the TCP connection between the server and client first.
Initializing library files
For both the server and client applications, issue the OPENSSL_init_ssl function to explicitly register the available ciphers and message digests for SSL library initialization. Otherwise, OpenSSL 1.1.0 and later will automatically allocate all resources without requiring explicit initialization.
Creating the SSL connection method
Create the SSL connection method by selecting the TLS versions that the server and client support.
Creating CTX and SSL structures
Create a context (CTX) and SSL structure for the server and client applications.
Specifying private keys to use
If the private key file is not stored in the z/TPF keystore, use the SSL_CTX_set_default_passwd_cb_userdata function to set the password that is needed to access the private key file.
Specifying digital certificates or a chain of digital certificates
Specify digital certificates or a chain of digital certificates that are used for any SSL sessions that are created by using a specific context (CTX) structure.
Verifying remote certificates
You need to verify the remote certificate for the server (if client authentication is used) and client applications.
Setting cipher suites
Issue a correct function to set cipher suites that the client or server can use for your SSL sessions.
Starting an SSL session
You need to start an SSL session for the server and client applications.
Writing and reading data
The server and client applications need to read and write data over an SSL session.
Ending an SSL session
You need to end an SSL session for only the client application. Issue the SSL_shutdown function to shut down data flow for an SSL session, which is the normal way to shut down an SSL session. Shut down an SSL session before the socket is shut down and closed.
Cleaning up CTX and SSL structures
The server and client applications needs to clean up context (CTX) and SSL structures by returning them.
Ending the TCP connection
The server and client applications need to issue the close function to shut down the connected socket and release resources that are allocated to that socket.
Querying SSL applications
Query SSL applications for the server and client.

Parent topic: Secure Sockets Layer