SSL(7SSL)                           OpenSSL                           SSL(7SSL)

NAME
       ssl - OpenSSL SSL/TLS library

SYNOPSIS
       See the individual manual pages for details.

DESCRIPTION
       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.

DATA STRUCTURES
       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.

HEADER FILES
       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
       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>.

3.0.10                             2024‐02‐21                         SSL(7SSL)