5 SSL_CTX_set_security_level, SSL_set_security_level, SSL_CTX_get_security_level, SSL_get_security_level, SSL_CTX_set_security_callback, SSL_set_security_callback, SSL_CTX_get_security_callback, SSL_get_security_callback, SSL_CTX_set0_security_ex_data, SSL_set0_security_ex_data, SSL_CTX_get0_security_ex_data, SSL_get0_security_ex_data - SSL/TLS security framework
9 #include <openssl/ssl.h>
11 void SSL_CTX_set_security_level(SSL_CTX *ctx, int level);
12 void SSL_set_security_level(SSL *s, int level);
14 int SSL_CTX_get_security_level(const SSL_CTX *ctx);
15 int SSL_get_security_level(const SSL *s);
17 void SSL_CTX_set_security_callback(SSL_CTX *ctx,
18 int (*cb)(SSL *s, SSL_CTX *ctx, int op,
20 void *other, void *ex));
22 void SSL_set_security_callback(SSL *s, int (*cb)(SSL *s, SSL_CTX *ctx, int op,
24 void *other, void *ex));
26 int (*SSL_CTX_get_security_callback(const SSL_CTX *ctx))(SSL *s, SSL_CTX *ctx, int op,
27 int bits, int nid, void *other,
29 int (*SSL_get_security_callback(const SSL *s))(SSL *s, SSL_CTX *ctx, int op,
30 int bits, int nid, void *other,
33 void SSL_CTX_set0_security_ex_data(SSL_CTX *ctx, void *ex);
34 void SSL_set0_security_ex_data(SSL *s, void *ex);
36 void *SSL_CTX_get0_security_ex_data(const SSL_CTX *ctx);
37 void *SSL_get0_security_ex_data(const SSL *s);
41 The functions SSL_CTX_set_security_level() and SSL_set_security_level() set
42 the security level to B<level>. If not set the library default security level
45 The functions SSL_CTX_get_security_level() and SSL_get_security_level()
46 retrieve the current security level.
48 SSL_CTX_set_security_callback(), SSL_set_security_callback(),
49 SSL_CTX_get_security_callback() and SSL_get_security_callback() get or set
50 the security callback associated with B<ctx> or B<s>. If not set a default
51 security callback is used. The meaning of the parameters and the behaviour
52 of the default callbacks is described below.
54 SSL_CTX_set0_security_ex_data(), SSL_set0_security_ex_data(),
55 SSL_CTX_get0_security_ex_data() and SSL_get0_security_ex_data() set the
56 extra data pointer passed to the B<ex> parameter of the callback. This
57 value is passed to the callback verbatim and can be set to any convenient
58 application specific value.
60 =head1 DEFAULT CALLBACK BEHAVIOUR
62 If an application doesn't set its own security callback the default
63 callback is used. It is intended to provide sane defaults. The meaning
64 of each level is described below.
70 Everything is permitted. This retains compatibility with previous versions of
75 The security level corresponds to a minimum of 80 bits of security. Any
76 parameters offering below 80 bits of security are excluded. As a result RSA,
77 DSA and DH keys shorter than 1024 bits and ECC keys shorter than 160 bits
78 are prohibited. Any cipher suite using MD5 for the MAC is also prohibited. Any
79 cipher suites using CCM with a 64 bit authentication tag are prohibited. Note
80 that signatures using SHA1 and MD5 are also forbidden at this level as they
81 have less than 80 security bits.
85 Security level set to 112 bits of security. As a result RSA, DSA and DH keys
86 shorter than 2048 bits and ECC keys shorter than 224 bits are prohibited.
87 In addition to the level 1 exclusions any cipher suite using RC4 is also
88 prohibited. SSL version 3 is also not allowed. Compression is disabled.
92 Security level set to 128 bits of security. As a result RSA, DSA and DH keys
93 shorter than 3072 bits and ECC keys shorter than 256 bits are prohibited.
94 In addition to the level 2 exclusions cipher suites not offering forward
95 secrecy are prohibited. TLS versions below 1.1 are not permitted. Session
100 Security level set to 192 bits of security. As a result RSA, DSA and
101 DH keys shorter than 7680 bits and ECC keys shorter than 384 bits are
102 prohibited. Cipher suites using SHA1 for the MAC are prohibited. TLS
103 versions below 1.2 are not permitted.
107 Security level set to 256 bits of security. As a result RSA, DSA and DH keys
108 shorter than 15360 bits and ECC keys shorter than 512 bits are prohibited.
112 =head1 APPLICATION DEFINED SECURITY CALLBACKS
114 I<Documentation to be provided.>
118 The default security level can be configured when OpenSSL is compiled by
119 setting B<-DOPENSSL_TLS_SECURITY_LEVEL=level>. If not set then 2 is used.
121 The security framework disables or reject parameters inconsistent with the
122 set security level. In the past this was difficult as applications had to set
123 a number of distinct parameters (supported ciphers, supported curves supported
124 signature algorithms) to achieve this end and some cases (DH parameter size
125 for example) could not be checked at all.
127 By setting an appropriate security level much of this complexity can be
130 The bits of security limits affect all relevant parameters including
131 cipher suite encryption algorithms, supported ECC curves, supported
132 signature algorithms, DH parameter sizes, certificate key sizes and
133 signature algorithms. This limit applies no matter what other custom
134 settings an application has set: so if the cipher suite is set to B<ALL>
135 then only cipher suites consistent with the security level are permissible.
137 See SP800-57 for how the security limits are related to individual
140 Some security levels require large key sizes for non-ECC public key
141 algorithms which can severely degrade performance. For example 256 bits
142 of security requires the use of RSA keys of at least 15360 bits in size.
144 Some restrictions can be gracefully handled: for example cipher suites
145 offering insufficient security are not sent by the client and will not
146 be selected by the server. Other restrictions such as the peer certificate
147 key size or the DH parameter size will abort the handshake with a fatal
150 Attempts to set certificates or parameters with insufficient security are
151 also blocked. For example trying to set a certificate using a 512 bit RSA key
152 or a certificate with a signature with SHA1 digest at level 1 using
153 SSL_CTX_use_certificate(). Applications which do not check the return values
154 for errors will misbehave: for example it might appear that a certificate is
155 not set at all because it had been rejected.
159 SSL_CTX_set_security_level() and SSL_set_security_level() do not return values.
161 SSL_CTX_get_security_level() and SSL_get_security_level() return a integer that
162 represents the security level with B<SSL_CTX> or B<SSL>, respectively.
164 SSL_CTX_set_security_callback() and SSL_set_security_callback() do not return
167 SSL_CTX_get_security_callback() and SSL_get_security_callback() return the pointer
168 to the security callback or NULL if the callback is not set.
170 SSL_CTX_get0_security_ex_data() and SSL_get0_security_ex_data() return the extra
171 data pointer or NULL if the ex data is not set.
179 These functions were added in OpenSSL 1.1.0.
183 Copyright 2014-2020 The OpenSSL Project Authors. All Rights Reserved.
185 Licensed under the Apache License 2.0 (the "License"). You may not use
186 this file except in compliance with the License. You can obtain a copy
187 in the file LICENSE in the source distribution or at
188 L<https://www.openssl.org/source/license.html>.