# SSL(7SSL) - man - phpMan

[SSL(7SSL)](https://www.chedong.com/phpMan.php/man/SSL/7SSL/markdown)                                      OpenSSL                                     [SSL(7SSL)](https://www.chedong.com/phpMan.php/man/SSL/7SSL/markdown)



## 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)](https://www.chedong.com/phpMan.php/man/new/3/markdown)).  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)](https://www.chedong.com/phpMan.php/man/new/3/markdown), **SSL**___**set**___**[fd**(3)](https://www.chedong.com/phpMan.php/man/fd/3/markdown) or **SSL**___**set**___**[bio**(3)](https://www.chedong.com/phpMan.php/man/bio/3/markdown) can be used to
       associate the network connection with the object.

       When the TLS/SSL handshake is performed using **SSL**___**[accept**(3)](https://www.chedong.com/phpMan.php/man/accept/3/markdown) or **SSL**___**[connect**(3)](https://www.chedong.com/phpMan.php/man/connect/3/markdown) respectively.
       **SSL**___**read**___**[ex**(3)](https://www.chedong.com/phpMan.php/man/ex/3/markdown), **SSL**___**[read**(3)](https://www.chedong.com/phpMan.php/man/read/3/markdown), **SSL**___**write**___**[ex**(3)](https://www.chedong.com/phpMan.php/man/ex/3/markdown) and **SSL**___**[write**(3)](https://www.chedong.com/phpMan.php/man/write/3/markdown) are used to read and write data
       on the TLS/SSL connection.  **SSL**___**[shutdown**(3)](https://www.chedong.com/phpMan.php/man/shutdown/3/markdown) 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**___**CIPHER**s, 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>>.



3.0.2                                        2026-04-07                                    [SSL(7SSL)](https://www.chedong.com/phpMan.php/man/SSL/7SSL/markdown)