6 SSLv23_method, SSLv23_server_method, SSLv23_client_method,
7 TLSv1_2_method, TLSv1_2_server_method, TLSv1_2_client_method,
8 TLSv1_1_method, TLSv1_1_server_method, TLSv1_1_client_method,
9 TLSv1_method, TLSv1_server_method, TLSv1_client_method,
10 SSLv3_method, SSLv3_server_method, SSLv3_client_method,
11 SSLv2_method, SSLv2_server_method, SSLv2_client_method,
12 DTLS_method, DTLS_server_method, DTLS_client_method,
13 DTLSv1_2_method, DTLSv1_2_server_method, DTLSv1_2_client_method,
14 DTLSv1_method, DTLSv1_server_method, DTLSv1_client_method -
15 create a new SSL_CTX object as framework for TLS/SSL enabled functions
19 #include <openssl/ssl.h>
21 SSL_CTX *SSL_CTX_new(const SSL_METHOD *method);
22 const SSL_METHOD *SSLv23_method(void);
23 const SSL_METHOD *SSLv23_server_method(void);
24 const SSL_METHOD *SSLv23_client_method(void);
25 const SSL_METHOD *TLSv1_2_method(void);
26 const SSL_METHOD *TLSv1_2_server_method(void);
27 const SSL_METHOD *TLSv1_2_client_method(void);
28 const SSL_METHOD *TLSv1_1_method(void);
29 const SSL_METHOD *TLSv1_1_server_method(void);
30 const SSL_METHOD *TLSv1_1_client_method(void);
31 const SSL_METHOD *TLSv1_method(void);
32 const SSL_METHOD *TLSv1_server_method(void);
33 const SSL_METHOD *TLSv1_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);
39 #ifndef OPENSSL_NO_SSL2
40 const SSL_METHOD *SSLv2_method(void);
41 const SSL_METHOD *SSLv2_server_method(void);
42 const SSL_METHOD *SSLv2_client_method(void);
45 const SSL_METHOD *DTLS_method(void);
46 const SSL_METHOD *DTLS_server_method(void);
47 const SSL_METHOD *DTLS_client_method(void);
48 const SSL_METHOD *DTLSv1_2_method(void);
49 const SSL_METHOD *DTLSv1_2_server_method(void);
50 const SSL_METHOD *DTLSv1_2_client_method(void);
51 const SSL_METHOD *DTLSv1_method(void);
52 const SSL_METHOD *DTLSv1_server_method(void);
53 const SSL_METHOD *DTLSv1_client_method(void);
57 SSL_CTX_new() creates a new B<SSL_CTX> object as framework to establish
58 TLS/SSL enabled connections.
62 The SSL_CTX object uses B<method> as connection method. The methods exist
63 in a generic type (for client and server use), a server only type, and a
64 client only type. B<method> can be of the following types:
68 =item SSLv23_method(), SSLv23_server_method(), SSLv23_client_method()
70 These are the general-purpose I<version-flexible> SSL/TLS methods.
71 The actual protocol version used will be negotiated to the highest version
72 mutually supported by the client and the server.
73 The supported protocols are SSLv2, SSLv3, TLSv1, TLSv1.1 and TLSv1.2.
74 Most applications should use these method, and avoid the version specific
75 methods described below.
77 The list of protocols available can be further limited using the
78 B<SSL_OP_NO_SSLv2>, B<SSL_OP_NO_SSLv3>, B<SSL_OP_NO_TLSv1>,
79 B<SSL_OP_NO_TLSv1_1> and B<SSL_OP_NO_TLSv1_2> options of the
80 L<SSL_CTX_set_options(3)> or L<SSL_set_options(3)> functions.
81 Clients should avoid creating "holes" in the set of protocols they support,
82 when disabling a protocol, make sure that you also disable either all previous
83 or all subsequent protocol versions.
84 In clients, when a protocol version is disabled without disabling I<all>
85 previous protocol versions, the effect is to also disable all subsequent
88 The SSLv2 and SSLv3 protocols are deprecated and should generally not be used.
89 Applications should typically use L<SSL_CTX_set_options(3)> in combination with
90 the B<SSL_OP_NO_SSLv3> flag to disable negotiation of SSLv3 via the above
91 I<version-flexible> SSL/TLS methods.
92 The B<SSL_OP_NO_SSLv2> option is set by default, and would need to be cleared
93 via L<SSL_CTX_clear_options(3)> in order to enable negotiation of SSLv2.
95 =item TLSv1_2_method(), TLSv1_2_server_method(), TLSv1_2_client_method()
97 A TLS/SSL connection established with these methods will only understand the
98 TLSv1.2 protocol. A client will send out TLSv1.2 client hello messages and
99 will also indicate that it only understand TLSv1.2. A server will only
100 understand TLSv1.2 client hello messages.
102 =item TLSv1_1_method(), TLSv1_1_server_method(), TLSv1_1_client_method()
104 A TLS/SSL connection established with these methods will only understand the
105 TLSv1.1 protocol. A client will send out TLSv1.1 client hello messages and
106 will also indicate that it only understand TLSv1.1. A server will only
107 understand TLSv1.1 client hello messages.
109 =item TLSv1_method(), TLSv1_server_method(), TLSv1_client_method()
111 A TLS/SSL connection established with these methods will only understand the
112 TLSv1 protocol. A client will send out TLSv1 client hello messages and will
113 indicate that it only understands TLSv1. A server will only understand TLSv1
114 client hello messages.
116 =item SSLv3_method(), SSLv3_server_method(), SSLv3_client_method()
118 A TLS/SSL connection established with these methods will only understand the
119 SSLv3 protocol. A client will send out SSLv3 client hello messages and will
120 indicate that it only understands SSLv3. A server will only understand SSLv3
121 client hello messages. The SSLv3 protocol is deprecated and should not be
124 =item SSLv2_method(), SSLv2_server_method(), SSLv2_client_method()
126 A TLS/SSL connection established with these methods will only understand the
127 SSLv2 protocol. A client will send out SSLv2 client hello messages and will
128 also indicate that it only understand SSLv2. A server will only understand
129 SSLv2 client hello messages. The SSLv2 protocol offers little to no security
130 and should not be used.
131 As of OpenSSL 1.0.2g, EXPORT ciphers and 56-bit DES are no longer available
134 =item DTLS_method(), DTLS_server_method(), DTLS_client_method()
136 These are the version-flexible DTLS methods.
138 =item DTLSv1_2_method(), DTLSv1_2_server_method(), DTLSv1_2_client_method()
140 These are the version-specific methods for DTLSv1.2.
142 =item DTLSv1_method(), DTLSv1_server_method(), DTLSv1_client_method()
144 These are the version-specific methods for DTLSv1.
148 SSL_CTX_new() initializes the list of ciphers, the session cache setting, the
149 callbacks, the keys and certificates and the options to its default values.
153 The following return values can occur:
159 The creation of a new SSL_CTX object failed. Check the error stack to find out
162 =item Pointer to an SSL_CTX object
164 The return value points to an allocated SSL_CTX object.
170 L<SSL_CTX_set_options(3)>, L<SSL_CTX_clear_options(3)>, L<SSL_set_options(3)>,
171 L<SSL_CTX_free(3)|SSL_CTX_free(3)>, L<SSL_accept(3)|SSL_accept(3)>,
172 L<ssl(3)|ssl(3)>, L<SSL_set_connect_state(3)|SSL_set_connect_state(3)>