5 TLSv1_2_method, TLSv1_2_server_method, TLSv1_2_client_method,
6 SSL_CTX_new, SSL_CTX_new_with_libctx, SSL_CTX_up_ref, SSLv3_method,
7 SSLv3_server_method, SSLv3_client_method, TLSv1_method, TLSv1_server_method,
8 TLSv1_client_method, TLSv1_1_method, TLSv1_1_server_method,
9 TLSv1_1_client_method, TLS_method, TLS_server_method, TLS_client_method,
10 SSLv23_method, SSLv23_server_method, SSLv23_client_method, DTLS_method,
11 DTLS_server_method, DTLS_client_method, DTLSv1_method, DTLSv1_server_method,
12 DTLSv1_client_method, DTLSv1_2_method, DTLSv1_2_server_method,
13 DTLSv1_2_client_method
14 - create a new SSL_CTX object as framework for TLS/SSL or DTLS enabled
19 #include <openssl/ssl.h>
21 SSL_CTX *SSL_CTX_new_with_libctx(OPENSSL_CTX *libctx, const char *propq,
22 const SSL_METHOD *method);
23 SSL_CTX *SSL_CTX_new(const SSL_METHOD *method);
24 int SSL_CTX_up_ref(SSL_CTX *ctx);
26 const SSL_METHOD *TLS_method(void);
27 const SSL_METHOD *TLS_server_method(void);
28 const SSL_METHOD *TLS_client_method(void);
30 const SSL_METHOD *SSLv23_method(void);
31 const SSL_METHOD *SSLv23_server_method(void);
32 const SSL_METHOD *SSLv23_client_method(void);
34 #ifndef OPENSSL_NO_SSL3_METHOD
35 const SSL_METHOD *SSLv3_method(void);
36 const SSL_METHOD *SSLv3_server_method(void);
37 const SSL_METHOD *SSLv3_client_method(void);
40 #ifndef OPENSSL_NO_TLS1_METHOD
41 const SSL_METHOD *TLSv1_method(void);
42 const SSL_METHOD *TLSv1_server_method(void);
43 const SSL_METHOD *TLSv1_client_method(void);
46 #ifndef OPENSSL_NO_TLS1_1_METHOD
47 const SSL_METHOD *TLSv1_1_method(void);
48 const SSL_METHOD *TLSv1_1_server_method(void);
49 const SSL_METHOD *TLSv1_1_client_method(void);
52 #ifndef OPENSSL_NO_TLS1_2_METHOD
53 const SSL_METHOD *TLSv1_2_method(void);
54 const SSL_METHOD *TLSv1_2_server_method(void);
55 const SSL_METHOD *TLSv1_2_client_method(void);
58 const SSL_METHOD *DTLS_method(void);
59 const SSL_METHOD *DTLS_server_method(void);
60 const SSL_METHOD *DTLS_client_method(void);
62 #ifndef OPENSSL_NO_DTLS1_METHOD
63 const SSL_METHOD *DTLSv1_method(void);
64 const SSL_METHOD *DTLSv1_server_method(void);
65 const SSL_METHOD *DTLSv1_client_method(void);
68 #ifndef OPENSSL_NO_DTLS1_2_METHOD
69 const SSL_METHOD *DTLSv1_2_method(void);
70 const SSL_METHOD *DTLSv1_2_server_method(void);
71 const SSL_METHOD *DTLSv1_2_client_method(void);
76 SSL_CTX_new_with_libctx() creates a new B<SSL_CTX> object as a framework to
77 establish TLS/SSL or DTLS enabled connections using the library context
78 I<libctx> (see L<OPENSSL_CTX(3)>). Any cryptographic algorithms that are used
79 by any B<SSL> objects created from this B<SSL_CTX> will be fetched from the
80 I<libctx> using the property query string I<propq> (see
81 L<provider(7)/Fetching algorithms>. Either or both the I<libctx> or I<propq>
82 parameters may be NULL.
84 SSL_CTX_new() does the same as SSL_CTX_new_with_libctx() except that the default
85 library context is used and no property query string is specified.
87 An B<SSL_CTX> object is reference counted. Creating an B<SSL_CTX> object for the
88 first time increments the reference count. Freeing the B<SSL_CTX> (using
89 SSL_CTX_free) decrements it. When the reference count drops to zero, any memory
90 or resources allocated to the B<SSL_CTX> object are freed. SSL_CTX_up_ref()
91 increments the reference count for an existing B<SSL_CTX> structure.
95 The SSL_CTX object uses I<method> as the connection method.
96 The methods exist in a generic type (for client and server use), a server only
97 type, and a client only type.
98 B<method> can be one of the following types:
102 =item TLS_method(), TLS_server_method(), TLS_client_method()
104 These are the general-purpose I<version-flexible> SSL/TLS methods.
105 The actual protocol version used will be negotiated to the highest version
106 mutually supported by the client and the server.
107 The supported protocols are SSLv3, TLSv1, TLSv1.1, TLSv1.2 and TLSv1.3.
108 Applications should use these methods, and avoid the version-specific
109 methods described below, which are deprecated.
111 =item SSLv23_method(), SSLv23_server_method(), SSLv23_client_method()
113 These functions do not exist anymore, they have been renamed to
114 TLS_method(), TLS_server_method() and TLS_client_method() respectively.
115 Currently, the old function calls are renamed to the corresponding new
116 ones by preprocessor macros, to ensure that existing code which uses the
117 old function names still compiles. However, using the old function names
118 is deprecated and new code should call the new functions instead.
120 =item TLSv1_2_method(), TLSv1_2_server_method(), TLSv1_2_client_method()
122 A TLS/SSL connection established with these methods will only understand the
123 TLSv1.2 protocol. These methods are deprecated.
125 =item TLSv1_1_method(), TLSv1_1_server_method(), TLSv1_1_client_method()
127 A TLS/SSL connection established with these methods will only understand the
128 TLSv1.1 protocol. These methods are deprecated.
130 =item TLSv1_method(), TLSv1_server_method(), TLSv1_client_method()
132 A TLS/SSL connection established with these methods will only understand the
133 TLSv1 protocol. These methods are deprecated.
135 =item SSLv3_method(), SSLv3_server_method(), SSLv3_client_method()
137 A TLS/SSL connection established with these methods will only understand the
139 The SSLv3 protocol is deprecated and should not be used.
141 =item DTLS_method(), DTLS_server_method(), DTLS_client_method()
143 These are the version-flexible DTLS methods.
144 Currently supported protocols are DTLS 1.0 and DTLS 1.2.
146 =item DTLSv1_2_method(), DTLSv1_2_server_method(), DTLSv1_2_client_method()
148 These are the version-specific methods for DTLSv1.2.
149 These methods are deprecated.
151 =item DTLSv1_method(), DTLSv1_server_method(), DTLSv1_client_method()
153 These are the version-specific methods for DTLSv1.
154 These methods are deprecated.
158 SSL_CTX_new() initializes the list of ciphers, the session cache setting, the
159 callbacks, the keys and certificates and the options to their default values.
161 TLS_method(), TLS_server_method(), TLS_client_method(), DTLS_method(),
162 DTLS_server_method() and DTLS_client_method() are the I<version-flexible>
164 All other methods only support one specific protocol version.
165 Use the I<version-flexible> methods instead of the version specific methods.
167 If you want to limit the supported protocols for the version flexible
168 methods you can use L<SSL_CTX_set_min_proto_version(3)>,
169 L<SSL_set_min_proto_version(3)>, L<SSL_CTX_set_max_proto_version(3)> and
170 L<SSL_set_max_proto_version(3)> functions.
171 Using these functions it is possible to choose e.g. TLS_server_method()
172 and be able to negotiate with all possible clients, but to only
173 allow newer protocols like TLS 1.0, TLS 1.1, TLS 1.2 or TLS 1.3.
175 The list of protocols available can also be limited using the
176 B<SSL_OP_NO_SSLv3>, B<SSL_OP_NO_TLSv1>, B<SSL_OP_NO_TLSv1_1>,
177 B<SSL_OP_NO_TLSv1_3>, B<SSL_OP_NO_TLSv1_2> and B<SSL_OP_NO_TLSv1_3>
179 L<SSL_CTX_set_options(3)> or L<SSL_set_options(3)> functions, but this approach
180 is not recommended. Clients should avoid creating "holes" in the set of
181 protocols they support. When disabling a protocol, make sure that you also
182 disable either all previous or all subsequent protocol versions.
183 In clients, when a protocol version is disabled without disabling I<all>
184 previous protocol versions, the effect is to also disable all subsequent
187 The SSLv3 protocol is deprecated and should generally not be used.
188 Applications should typically use L<SSL_CTX_set_min_proto_version(3)> to set
189 the minimum protocol to at least B<TLS1_VERSION>.
193 The following return values can occur:
199 The creation of a new SSL_CTX object failed. Check the error stack to find out
202 =item Pointer to an SSL_CTX object
204 The return value points to an allocated SSL_CTX object.
206 SSL_CTX_up_ref() returns 1 for success and 0 for failure.
212 L<SSL_CTX_set_options(3)>, L<SSL_CTX_free(3)>, L<SSL_accept(3)>,
213 L<SSL_CTX_set_min_proto_version(3)>, L<ssl(7)>, L<SSL_set_connect_state(3)>
217 Support for SSLv2 and the corresponding SSLv2_method(),
218 SSLv2_server_method() and SSLv2_client_method() functions where
219 removed in OpenSSL 1.1.0.
221 SSLv23_method(), SSLv23_server_method() and SSLv23_client_method()
222 were deprecated and the preferred TLS_method(), TLS_server_method()
223 and TLS_client_method() functions were added in OpenSSL 1.1.0.
225 All version-specific methods were deprecated in OpenSSL 1.1.0.
227 SSL_CTX_new_with_libctx() was added in OpenSSL 3.0.
231 Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
233 Licensed under the Apache License 2.0 (the "License"). You may not use
234 this file except in compliance with the License. You can obtain a copy
235 in the file LICENSE in the source distribution or at
236 L<https://www.openssl.org/source/license.html>.