1=pod 2 3=head1 NAME 4 5ssl - OpenSSL SSL/TLS library 6 7=head1 SYNOPSIS 8 9See the individual manual pages for details. 10 11=head1 DESCRIPTION 12 13The OpenSSL B<ssl> library implements several versions of the 14Secure Sockets Layer, Transport Layer Security, and Datagram Transport Layer 15Security protocols. 16This page gives a brief overview of the extensive API and data types 17provided by the library. 18 19An B<SSL_CTX> object is created as a framework to establish 20TLS/SSL enabled connections (see L<SSL_CTX_new(3)>). 21Various options regarding certificates, algorithms etc. can be set 22in this object. 23 24When a network connection has been created, it can be assigned to an 25B<SSL> object. After the B<SSL> object has been created using 26L<SSL_new(3)>, L<SSL_set_fd(3)> or 27L<SSL_set_bio(3)> can be used to associate the network 28connection with the object. 29 30When the TLS/SSL handshake is performed using 31L<SSL_accept(3)> or L<SSL_connect(3)> 32respectively. 33L<SSL_read_ex(3)>, L<SSL_read(3)>, L<SSL_write_ex(3)> and L<SSL_write(3)> are 34used to read and write data on the TLS/SSL connection. 35L<SSL_shutdown(3)> can be used to shut down the 36TLS/SSL connection. 37 38=head1 DATA STRUCTURES 39 40Here are some of the main data structures in the library. 41 42=over 4 43 44=item B<SSL_METHOD> (SSL Method) 45 46This is a dispatch structure describing the internal B<ssl> library 47methods/functions which implement the various protocol versions (SSLv3 48TLSv1, ...). It's needed to create an B<SSL_CTX>. 49 50=item B<SSL_CIPHER> (SSL Cipher) 51 52This structure holds the algorithm information for a particular cipher which 53are a core part of the SSL/TLS protocol. The available ciphers are configured 54on a B<SSL_CTX> basis and the actual ones used are then part of the 55B<SSL_SESSION>. 56 57=item B<SSL_CTX> (SSL Context) 58 59This is the global context structure which is created by a server or client 60once per program life-time and which holds mainly default values for the 61B<SSL> structures which are later created for the connections. 62 63=item B<SSL_SESSION> (SSL Session) 64 65This is a structure containing the current TLS/SSL session details for a 66connection: B<SSL_CIPHER>s, client and server certificates, keys, etc. 67 68=item B<SSL> (SSL Connection) 69 70This is the main SSL/TLS structure which is created by a server or client per 71established connection. This actually is the core structure in the SSL API. 72At run-time the application usually deals with this structure which has 73links to mostly all other structures. 74 75=back 76 77=head1 HEADER FILES 78 79Currently the OpenSSL B<ssl> library provides the following C header files 80containing the prototypes for the data structures and functions: 81 82=over 4 83 84=item F<< <openssl/ssl.h> >> 85 86This is the common header file for the SSL/TLS API. Include it into your 87program to make the API of the B<ssl> library available. It internally 88includes both more private SSL headers and headers from the B<crypto> library. 89Whenever you need hard-core details on the internals of the SSL API, look 90inside this header file. 91This file also includes the others listed below. 92 93=item F<< <openssl/ssl2.h> >> 94 95Unused. Present for backwards compatibility only. 96 97=item F<< <openssl/ssl3.h> >> 98 99This is the sub header file dealing with the SSLv3 protocol only. 100 101=item F<< <openssl/tls1.h> >> 102 103This is the sub header file dealing with the TLSv1 protocol only. 104 105=back 106 107=head1 COPYRIGHT 108 109Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved. 110 111Licensed under the Apache License 2.0 (the "License"). You may not use 112this file except in compliance with the License. You can obtain a copy 113in the file LICENSE in the source distribution or at 114L<https://www.openssl.org/source/license.html>. 115 116=cut 117