5 X509_VERIFY_PARAM_set_flags, X509_VERIFY_PARAM_clear_flags,
6 X509_VERIFY_PARAM_get_flags, X509_VERIFY_PARAM_set_purpose,
7 X509_VERIFY_PARAM_get_inh_flags, X509_VERIFY_PARAM_set_inh_flags,
8 X509_VERIFY_PARAM_set_trust, X509_VERIFY_PARAM_set_depth,
9 X509_VERIFY_PARAM_get_depth, X509_VERIFY_PARAM_set_auth_level,
10 X509_VERIFY_PARAM_get_auth_level, X509_VERIFY_PARAM_set_time,
11 X509_VERIFY_PARAM_get_time,
12 X509_VERIFY_PARAM_add0_policy, X509_VERIFY_PARAM_set1_policies,
13 X509_VERIFY_PARAM_set1_host, X509_VERIFY_PARAM_add1_host,
14 X509_VERIFY_PARAM_set_hostflags,
15 X509_VERIFY_PARAM_get_hostflags,
16 X509_VERIFY_PARAM_get0_peername,
17 X509_VERIFY_PARAM_set1_email, X509_VERIFY_PARAM_set1_ip,
18 X509_VERIFY_PARAM_set1_ip_asc
19 - X509 verification parameters
23 #include <openssl/x509_vfy.h>
25 int X509_VERIFY_PARAM_set_flags(X509_VERIFY_PARAM *param,
27 int X509_VERIFY_PARAM_clear_flags(X509_VERIFY_PARAM *param,
29 unsigned long X509_VERIFY_PARAM_get_flags(X509_VERIFY_PARAM *param);
31 int X509_VERIFY_PARAM_set_inh_flags(X509_VERIFY_PARAM *param,
33 uint32_t X509_VERIFY_PARAM_get_inh_flags(const X509_VERIFY_PARAM *param);
35 int X509_VERIFY_PARAM_set_purpose(X509_VERIFY_PARAM *param, int purpose);
36 int X509_VERIFY_PARAM_set_trust(X509_VERIFY_PARAM *param, int trust);
38 void X509_VERIFY_PARAM_set_time(X509_VERIFY_PARAM *param, time_t t);
39 time_t X509_VERIFY_PARAM_get_time(const X509_VERIFY_PARAM *param);
41 int X509_VERIFY_PARAM_add0_policy(X509_VERIFY_PARAM *param,
43 int X509_VERIFY_PARAM_set1_policies(X509_VERIFY_PARAM *param,
44 STACK_OF(ASN1_OBJECT) *policies);
46 void X509_VERIFY_PARAM_set_depth(X509_VERIFY_PARAM *param, int depth);
47 int X509_VERIFY_PARAM_get_depth(const X509_VERIFY_PARAM *param);
49 void X509_VERIFY_PARAM_set_auth_level(X509_VERIFY_PARAM *param,
51 int X509_VERIFY_PARAM_get_auth_level(const X509_VERIFY_PARAM *param);
53 int X509_VERIFY_PARAM_set1_host(X509_VERIFY_PARAM *param,
54 const char *name, size_t namelen);
55 int X509_VERIFY_PARAM_add1_host(X509_VERIFY_PARAM *param,
56 const char *name, size_t namelen);
57 void X509_VERIFY_PARAM_set_hostflags(X509_VERIFY_PARAM *param,
59 unsigned int X509_VERIFY_PARAM_get_hostflags(const X509_VERIFY_PARAM *param);
60 char *X509_VERIFY_PARAM_get0_peername(X509_VERIFY_PARAM *param);
61 int X509_VERIFY_PARAM_set1_email(X509_VERIFY_PARAM *param,
62 const char *email, size_t emaillen);
63 int X509_VERIFY_PARAM_set1_ip(X509_VERIFY_PARAM *param,
64 const unsigned char *ip, size_t iplen);
65 int X509_VERIFY_PARAM_set1_ip_asc(X509_VERIFY_PARAM *param, const char *ipasc);
69 These functions manipulate the B<X509_VERIFY_PARAM> structure associated with
70 a certificate verification operation.
72 The X509_VERIFY_PARAM_set_flags() function sets the flags in B<param> by oring
73 it with B<flags>. See the B<VERIFICATION FLAGS> section for a complete
74 description of values the B<flags> parameter can take.
76 X509_VERIFY_PARAM_get_flags() returns the flags in B<param>.
78 X509_VERIFY_PARAM_get_inh_flags() returns the inheritance flags in B<param>
79 which specifies how verification flags are copied from one structure to
80 another. X509_VERIFY_PARAM_set_inh_flags() sets the inheritance flags.
81 See the B<INHERITANCE FLAGS> section for a description of these bits.
83 X509_VERIFY_PARAM_clear_flags() clears the flags B<flags> in B<param>.
85 X509_VERIFY_PARAM_set_purpose() sets the verification purpose in B<param>
86 to B<purpose>. This determines the acceptable purpose of the certificate
87 chain, for example SSL client or SSL server.
89 X509_VERIFY_PARAM_set_trust() sets the trust setting in B<param> to
92 X509_VERIFY_PARAM_set_time() sets the verification time in B<param> to
93 B<t>. Normally the current time is used.
95 X509_VERIFY_PARAM_add0_policy() adds B<policy> to the acceptable policy set.
96 Contrary to preexisting documentation of this function it does not enable
99 X509_VERIFY_PARAM_set1_policies() enables policy checking (it is disabled
100 by default) and sets the acceptable policy set to B<policies>. Any existing
101 policy set is cleared. The B<policies> parameter can be B<NULL> to clear
102 an existing policy set.
104 X509_VERIFY_PARAM_set_depth() sets the maximum verification depth to B<depth>.
105 That is the maximum number of intermediate CA certificates that can appear in a
107 A maximal depth chain contains 2 more certificates than the limit, since
108 neither the end-entity certificate nor the trust-anchor count against this
110 Thus a B<depth> limit of 0 only allows the end-entity certificate to be signed
111 directly by the trust-anchor, while with a B<depth> limit of 1 there can be one
112 intermediate CA certificate between the trust-anchor and the end-entity
115 X509_VERIFY_PARAM_set_auth_level() sets the authentication security level to
117 The authentication security level determines the acceptable signature and public
118 key strength when verifying certificate chains.
119 For a certificate chain to validate, the public keys of all the certificates
120 must meet the specified security level.
121 The signature algorithm security level is not enforced for the chain's I<trust
122 anchor> certificate, which is either directly trusted or validated by means other
124 See L<SSL_CTX_set_security_level(3)> for the definitions of the available
126 The default security level is -1, or "not set".
127 At security level 0 or lower all algorithms are acceptable.
128 Security level 1 requires at least 80-bit-equivalent security and is broadly
129 interoperable, though it will, for example, reject MD5 signatures or RSA keys
130 shorter than 1024 bits.
132 X509_VERIFY_PARAM_set1_host() sets the expected DNS hostname to
133 B<name> clearing any previously specified hostname or names. If
134 B<name> is NULL, or empty the list of hostnames is cleared, and
135 name checks are not performed on the peer certificate. If B<name>
136 is NUL-terminated, B<namelen> may be zero, otherwise B<namelen>
137 must be set to the length of B<name>.
139 When a hostname is specified,
140 certificate verification automatically invokes L<X509_check_host(3)>
141 with flags equal to the B<flags> argument given to
142 X509_VERIFY_PARAM_set_hostflags() (default zero). Applications
143 are strongly advised to use this interface in preference to explicitly
144 calling L<X509_check_host(3)>, hostname checks may be out of scope
145 with the DANE-EE(3) certificate usage, and the internal check will
146 be suppressed as appropriate when DANE verification is enabled.
148 When the subject CommonName will not be ignored, whether as a result of the
149 B<X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT> host flag, or because no DNS subject
150 alternative names are present in the certificate, any DNS name constraints in
151 issuer certificates apply to the subject CommonName as well as the subject
152 alternative name extension.
154 When the subject CommonName will be ignored, whether as a result of the
155 B<X509_CHECK_FLAG_NEVER_CHECK_SUBJECT> host flag, or because some DNS subject
156 alternative names are present in the certificate, DNS name constraints in
157 issuer certificates will not be applied to the subject DN.
158 As described in X509_check_host(3) the B<X509_CHECK_FLAG_NEVER_CHECK_SUBJECT>
159 flag takes precedence over the B<X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT> flag.
161 X509_VERIFY_PARAM_get_hostflags() returns any host flags previously set via a
162 call to X509_VERIFY_PARAM_set_hostflags().
164 X509_VERIFY_PARAM_add1_host() adds B<name> as an additional reference
165 identifier that can match the peer's certificate. Any previous names
166 set via X509_VERIFY_PARAM_set1_host() or X509_VERIFY_PARAM_add1_host()
167 are retained, no change is made if B<name> is NULL or empty. When
168 multiple names are configured, the peer is considered verified when
171 X509_VERIFY_PARAM_get0_peername() returns the DNS hostname or subject
172 CommonName from the peer certificate that matched one of the reference
173 identifiers. When wildcard matching is not disabled, or when a
174 reference identifier specifies a parent domain (starts with ".")
175 rather than a hostname, the peer name may be a wildcard name or a
176 sub-domain of the reference identifier respectively. The return
177 string is allocated by the library and is no longer valid once the
178 associated B<param> argument is freed. Applications must not free
181 X509_VERIFY_PARAM_set1_email() sets the expected RFC822 email address to
182 B<email>. If B<email> is NUL-terminated, B<emaillen> may be zero, otherwise
183 B<emaillen> must be set to the length of B<email>. When an email address
184 is specified, certificate verification automatically invokes
185 L<X509_check_email(3)>.
187 X509_VERIFY_PARAM_set1_ip() sets the expected IP address to B<ip>.
188 The B<ip> argument is in binary format, in network byte-order and
189 B<iplen> must be set to 4 for IPv4 and 16 for IPv6. When an IP
190 address is specified, certificate verification automatically invokes
193 X509_VERIFY_PARAM_set1_ip_asc() sets the expected IP address to
194 B<ipasc>. The B<ipasc> argument is a NUL-terminal ASCII string:
195 dotted decimal quad for IPv4 and colon-separated hexadecimal for
196 IPv6. The condensed "::" notation is supported for IPv6 addresses.
200 X509_VERIFY_PARAM_set_flags(), X509_VERIFY_PARAM_clear_flags(),
201 X509_VERIFY_PARAM_set_inh_flags(),
202 X509_VERIFY_PARAM_set_purpose(), X509_VERIFY_PARAM_set_trust(),
203 X509_VERIFY_PARAM_add0_policy() X509_VERIFY_PARAM_set1_policies(),
204 X509_VERIFY_PARAM_set1_host(), X509_VERIFY_PARAM_add1_host(),
205 X509_VERIFY_PARAM_set1_email(), X509_VERIFY_PARAM_set1_ip() and
206 X509_VERIFY_PARAM_set1_ip_asc() return 1 for success and 0 for
209 X509_VERIFY_PARAM_get_flags() returns the current verification flags.
211 X509_VERIFY_PARAM_get_hostflags() returns any current host flags.
213 X509_VERIFY_PARAM_get_inh_flags() returns the current inheritance flags.
215 X509_VERIFY_PARAM_set_time() and X509_VERIFY_PARAM_set_depth() do not return
218 X509_VERIFY_PARAM_get_depth() returns the current verification depth.
220 X509_VERIFY_PARAM_get_auth_level() returns the current authentication security
223 =head1 VERIFICATION FLAGS
225 The verification flags consists of zero or more of the following flags
228 B<X509_V_FLAG_CRL_CHECK> enables CRL checking for the certificate chain leaf
229 certificate. An error occurs if a suitable CRL cannot be found.
231 B<X509_V_FLAG_CRL_CHECK_ALL> enables CRL checking for the entire certificate
234 B<X509_V_FLAG_IGNORE_CRITICAL> disabled critical extension checking. By default
235 any unhandled critical extensions in certificates or (if checked) CRLs results
236 in a fatal error. If this flag is set unhandled critical extensions are
237 ignored. B<WARNING> setting this option for anything other than debugging
238 purposes can be a security risk. Finer control over which extensions are
239 supported can be performed in the verification callback.
241 The B<X509_V_FLAG_X509_STRICT> flag disables workarounds for some broken
242 certificates and makes the verification strictly apply B<X509> rules.
244 B<X509_V_FLAG_ALLOW_PROXY_CERTS> enables proxy certificate verification.
246 B<X509_V_FLAG_POLICY_CHECK> enables certificate policy checking, by default
247 no policy checking is performed. Additional information is sent to the
248 verification callback relating to policy checking.
250 B<X509_V_FLAG_EXPLICIT_POLICY>, B<X509_V_FLAG_INHIBIT_ANY> and
251 B<X509_V_FLAG_INHIBIT_MAP> set the B<require explicit policy>, B<inhibit any
252 policy> and B<inhibit policy mapping> flags respectively as defined in
253 B<RFC3280>. Policy checking is automatically enabled if any of these flags
256 If B<X509_V_FLAG_NOTIFY_POLICY> is set and the policy checking is successful
257 a special status code is set to the verification callback. This permits it
258 to examine the valid policy tree and perform additional checks or simply
259 log it for debugging purposes.
261 By default some additional features such as indirect CRLs and CRLs signed by
262 different keys are disabled. If B<X509_V_FLAG_EXTENDED_CRL_SUPPORT> is set
265 If B<X509_V_FLAG_USE_DELTAS> is set delta CRLs (if present) are used to
266 determine certificate status. If not set deltas are ignored.
268 B<X509_V_FLAG_CHECK_SS_SIGNATURE> requests checking the signature of
269 the last certificate in a chain if the certificate is supposedly self-signed.
270 This is prohibited and will result in an error if it is a non-conforming CA
271 certificate with key usage restrictions not including the keyCertSign bit.
272 By default this check is disabled because it doesn't
273 add any additional security but in some cases applications might want to
274 check the signature anyway. A side effect of not checking the self-signature
275 of such a certificate is that disabled or unsupported message digests used for
276 the signature are not treated as fatal errors.
278 When B<X509_V_FLAG_TRUSTED_FIRST> is set, construction of the certificate chain
279 in L<X509_verify_cert(3)> will search the trust store for issuer certificates
280 before searching the provided untrusted certificates.
281 Local issuer certificates are often more likely to satisfy local security
282 requirements and lead to a locally trusted root.
283 This is especially important when some certificates in the trust store have
284 explicit trust settings (see "TRUST SETTINGS" in L<x509(1)>).
285 As of OpenSSL 1.1.0 this option is on by default.
287 The B<X509_V_FLAG_NO_ALT_CHAINS> flag suppresses checking for alternative
289 By default, unless B<X509_V_FLAG_TRUSTED_FIRST> is set, when building a
290 certificate chain, if the first certificate chain found is not trusted, then
291 OpenSSL will attempt to replace untrusted certificates supplied by the peer
292 with certificates from the trust store to see if an alternative chain can be
293 found that is trusted.
294 As of OpenSSL 1.1.0, with B<X509_V_FLAG_TRUSTED_FIRST> always set, this option
297 The B<X509_V_FLAG_PARTIAL_CHAIN> flag causes intermediate certificates in the
298 trust store to be treated as trust-anchors, in the same way as the self-signed
299 root CA certificates.
300 This makes it possible to trust certificates issued by an intermediate CA
301 without having to trust its ancestor root CA.
302 With OpenSSL 1.1.0 and later and <X509_V_FLAG_PARTIAL_CHAIN> set, chain
303 construction stops as soon as the first certificate from the trust store is
304 added to the chain, whether that certificate is a self-signed "root"
305 certificate or a not self-signed intermediate certificate.
306 Thus, when an intermediate certificate is found in the trust store, the
307 verified chain passed to callbacks may be shorter than it otherwise would
308 be without the B<X509_V_FLAG_PARTIAL_CHAIN> flag.
310 The B<X509_V_FLAG_NO_CHECK_TIME> flag suppresses checking the validity period
311 of certificates and CRLs against the current time. If X509_VERIFY_PARAM_set_time()
312 is used to specify a verification time, the check is not suppressed.
314 =head1 INHERITANCE FLAGS
316 These flags specify how parameters are "inherited" from one structure to
319 If B<X509_VP_FLAG_ONCE> is set then the current setting is zeroed
322 If B<X509_VP_FLAG_LOCKED> is set then no values are copied. This overrides
323 all of the following flags.
325 If B<X509_VP_FLAG_DEFAULT> is set then anything set in the source is copied
326 to the destination. Effectively the values in "to" become default values
327 which will be used only if nothing new is set in "from". This is the
330 If B<X509_VP_FLAG_OVERWRITE> is set then all value are copied across whether
331 they are set or not. Flags is still Ored though.
333 If B<X509_VP_FLAG_RESET_FLAGS> is set then the flags value is copied instead
338 The above functions should be used to manipulate verification parameters
339 instead of functions which work in specific structures such as
340 X509_STORE_CTX_set_flags() which are likely to be deprecated in a future
345 Delta CRL checking is currently primitive. Only a single delta can be used and
346 (partly due to limitations of B<X509_STORE>) constructed CRLs are not
349 If CRLs checking is enable CRLs are expected to be available in the
350 corresponding B<X509_STORE> structure. No attempt is made to download
351 CRLs from the CRL distribution points extension.
355 Enable CRL checking when performing certificate verification during SSL
356 connections associated with an B<SSL_CTX> structure B<ctx>:
358 X509_VERIFY_PARAM *param;
360 param = X509_VERIFY_PARAM_new();
361 X509_VERIFY_PARAM_set_flags(param, X509_V_FLAG_CRL_CHECK);
362 SSL_CTX_set1_param(ctx, param);
363 X509_VERIFY_PARAM_free(param);
367 L<X509_verify_cert(3)>,
368 L<X509_check_host(3)>,
369 L<X509_check_email(3)>,
375 The B<X509_V_FLAG_NO_ALT_CHAINS> flag was added in OpenSSL 1.1.0.
376 The flag B<X509_V_FLAG_CB_ISSUER_CHECK> was deprecated in OpenSSL 1.1.0
379 The X509_VERIFY_PARAM_get_hostflags() function was added in OpenSSL 1.1.0i.
381 The function X509_VERIFY_PARAM_add0_policy() was historically documented as
382 enabling policy checking however the implementation has never done this.
383 The documentation was changed to align with the implementation.
387 Copyright 2009-2020 The OpenSSL Project Authors. All Rights Reserved.
389 Licensed under the OpenSSL license (the "License"). You may not use
390 this file except in compliance with the License. You can obtain a copy
391 in the file LICENSE in the source distribution or at
392 L<https://www.openssl.org/source/license.html>.