ssl - OpenSSL SSL/TLS library
See the individual manual pages for details.
The OpenSSL ssl library implements several versions of the Secure Sockets
  Layer, Transport Layer Security, and Datagram Transport Layer Security
  protocols. This page gives a brief overview of the extensive API and data
  types provided by the library.
An SSL_CTX object is created as a framework to establish
    TLS/SSL enabled connections (see SSL_CTX_new(3)). Various options
    regarding certificates, algorithms etc. can be set in this object.
When a network connection has been created, it can be assigned to
    an SSL object. After the SSL object has been created using
    SSL_new(3), SSL_set_fd(3) or SSL_set_bio(3) can be used
    to associate the network connection with the object.
When the TLS/SSL handshake is performed using SSL_accept(3)
    or SSL_connect(3) respectively. SSL_read_ex(3),
    SSL_read(3), SSL_write_ex(3) and SSL_write(3) are used
    to read and write data on the TLS/SSL connection. SSL_shutdown(3) can
    be used to shut down the TLS/SSL connection.
Here are some of the main data structures in the library.
  - SSL_METHOD (SSL Method)
- This is a dispatch structure describing the internal ssl library
      methods/functions which implement the various protocol versions (SSLv3
      TLSv1, ...). It's needed to create an SSL_CTX.
- SSL_CIPHER (SSL Cipher)
- This structure holds the algorithm information for a particular cipher
      which are a core part of the SSL/TLS protocol. The available ciphers are
      configured on a SSL_CTX basis and the actual ones used are then
      part of the SSL_SESSION.
- SSL_CTX (SSL Context)
- This is the global context structure which is created by a server or
      client once per program life-time and which holds mainly default values
      for the SSL structures which are later created for the
    connections.
- SSL_SESSION (SSL Session)
- This is a structure containing the current TLS/SSL session details for a
      connection: SSL_CIPHERs, client and server certificates, keys,
    etc.
- SSL (SSL Connection)
- This is the main SSL/TLS structure which is created by a server or client
      per established connection. This actually is the core structure in the SSL
      API. At run-time the application usually deals with this structure which
      has links to mostly all other structures.
Currently the OpenSSL ssl library provides the following C header files
  containing the prototypes for the data structures and functions:
  - <openssl/ssl.h>
- This is the common header file for the SSL/TLS API. Include it into your
      program to make the API of the ssl library available. It internally
      includes both more private SSL headers and headers from the crypto
      library. Whenever you need hard-core details on the internals of the SSL
      API, look inside this header file. This file also includes the others
      listed below.
- <openssl/ssl2.h>
- Unused. Present for backwards compatibility only.
- <openssl/ssl3.h>
- This is the sub header file dealing with the SSLv3 protocol only.
- <openssl/tls1.h>
- This is the sub header file dealing with the TLSv1 protocol only.
Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.Licensed under the Apache License 2.0 (the "License").
    You may not use this file except in compliance with the License. You can
    obtain a copy in the file LICENSE in the source distribution or at
    <https://www.openssl.org/source/license.html>.