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_get0_host,
14 X509_VERIFY_PARAM_set1_host, X509_VERIFY_PARAM_add1_host,
15 X509_VERIFY_PARAM_set_hostflags,
16 X509_VERIFY_PARAM_get_hostflags,
17 X509_VERIFY_PARAM_get0_peername,
18 X509_VERIFY_PARAM_get0_email, X509_VERIFY_PARAM_set1_email,
19 X509_VERIFY_PARAM_set1_ip, X509_VERIFY_PARAM_get1_ip_asc,
20 X509_VERIFY_PARAM_set1_ip_asc
21 - X509 verification parameters
25 #include <openssl/x509_vfy.h>
27 int X509_VERIFY_PARAM_set_flags(X509_VERIFY_PARAM *param,
29 int X509_VERIFY_PARAM_clear_flags(X509_VERIFY_PARAM *param,
31 unsigned long X509_VERIFY_PARAM_get_flags(const X509_VERIFY_PARAM *param);
33 int X509_VERIFY_PARAM_set_inh_flags(X509_VERIFY_PARAM *param,
35 uint32_t X509_VERIFY_PARAM_get_inh_flags(const X509_VERIFY_PARAM *param);
37 int X509_VERIFY_PARAM_set_purpose(X509_VERIFY_PARAM *param, int purpose);
38 int X509_VERIFY_PARAM_set_trust(X509_VERIFY_PARAM *param, int trust);
40 void X509_VERIFY_PARAM_set_time(X509_VERIFY_PARAM *param, time_t t);
41 time_t X509_VERIFY_PARAM_get_time(const X509_VERIFY_PARAM *param);
43 int X509_VERIFY_PARAM_add0_policy(X509_VERIFY_PARAM *param,
45 int X509_VERIFY_PARAM_set1_policies(X509_VERIFY_PARAM *param,
46 STACK_OF(ASN1_OBJECT) *policies);
48 void X509_VERIFY_PARAM_set_depth(X509_VERIFY_PARAM *param, int depth);
49 int X509_VERIFY_PARAM_get_depth(const X509_VERIFY_PARAM *param);
51 void X509_VERIFY_PARAM_set_auth_level(X509_VERIFY_PARAM *param,
53 int X509_VERIFY_PARAM_get_auth_level(const X509_VERIFY_PARAM *param);
55 char *X509_VERIFY_PARAM_get0_host(X509_VERIFY_PARAM *param, int n);
56 int X509_VERIFY_PARAM_set1_host(X509_VERIFY_PARAM *param,
57 const char *name, size_t namelen);
58 int X509_VERIFY_PARAM_add1_host(X509_VERIFY_PARAM *param,
59 const char *name, size_t namelen);
60 void X509_VERIFY_PARAM_set_hostflags(X509_VERIFY_PARAM *param,
62 unsigned int X509_VERIFY_PARAM_get_hostflags(const X509_VERIFY_PARAM *param);
63 char *X509_VERIFY_PARAM_get0_peername(const X509_VERIFY_PARAM *param);
64 char *X509_VERIFY_PARAM_get0_email(X509_VERIFY_PARAM *param);
65 int X509_VERIFY_PARAM_set1_email(X509_VERIFY_PARAM *param,
66 const char *email, size_t emaillen);
67 char *X509_VERIFY_PARAM_get1_ip_asc(X509_VERIFY_PARAM *param);
68 int X509_VERIFY_PARAM_set1_ip(X509_VERIFY_PARAM *param,
69 const unsigned char *ip, size_t iplen);
70 int X509_VERIFY_PARAM_set1_ip_asc(X509_VERIFY_PARAM *param, const char *ipasc);
74 These functions manipulate the B<X509_VERIFY_PARAM> structure associated with
75 a certificate verification operation.
77 The X509_VERIFY_PARAM_set_flags() function sets the flags in B<param> by oring
78 it with B<flags>. See L</VERIFICATION FLAGS> for a complete
79 description of values the B<flags> parameter can take.
81 X509_VERIFY_PARAM_get_flags() returns the flags in B<param>.
83 X509_VERIFY_PARAM_get_inh_flags() returns the inheritance flags in B<param>
84 which specifies how verification flags are copied from one structure to
85 another. X509_VERIFY_PARAM_set_inh_flags() sets the inheritance flags.
86 See the B<INHERITANCE FLAGS> section for a description of these bits.
88 X509_VERIFY_PARAM_clear_flags() clears the flags B<flags> in B<param>.
90 X509_VERIFY_PARAM_set_purpose() sets the verification purpose in B<param>
91 to B<purpose>. This determines the acceptable purpose of the certificate
92 chain, for example B<X509_PURPOSE_SSL_CLIENT>.
94 X509_VERIFY_PARAM_set_trust() sets the trust setting in B<param> to
97 X509_VERIFY_PARAM_set_time() sets the verification time in B<param> to
98 B<t>. Normally the current time is used.
100 X509_VERIFY_PARAM_add0_policy() enables policy checking (it is disabled
101 by default) and adds B<policy> to the acceptable policy set.
103 X509_VERIFY_PARAM_set1_policies() enables policy checking (it is disabled
104 by default) and sets the acceptable policy set to B<policies>. Any existing
105 policy set is cleared. The B<policies> parameter can be B<NULL> to clear
106 an existing policy set.
108 X509_VERIFY_PARAM_set_depth() sets the maximum verification depth to B<depth>.
109 That is the maximum number of intermediate CA certificates that can appear in a
111 A maximal depth chain contains 2 more certificates than the limit, since
112 neither the end-entity certificate nor the trust-anchor count against this
114 Thus a B<depth> limit of 0 only allows the end-entity certificate to be signed
115 directly by the trust anchor, while with a B<depth> limit of 1 there can be one
116 intermediate CA certificate between the trust anchor and the end-entity
119 X509_VERIFY_PARAM_set_auth_level() sets the authentication security level to
121 The authentication security level determines the acceptable signature and public
122 key strength when verifying certificate chains.
123 For a certificate chain to validate, the public keys of all the certificates
124 must meet the specified security level.
125 The signature algorithm security level is not enforced for the chain's I<trust
126 anchor> certificate, which is either directly trusted or validated by means other
128 See L<SSL_CTX_set_security_level(3)> for the definitions of the available
130 The default security level is -1, or "not set".
131 At security level 0 or lower all algorithms are acceptable.
132 Security level 1 requires at least 80-bit-equivalent security and is broadly
133 interoperable, though it will, for example, reject MD5 signatures or RSA keys
134 shorter than 1024 bits.
136 X509_VERIFY_PARAM_get0_host() returns the B<n>th expected DNS hostname that has
137 been set using X509_VERIFY_PARAM_set1_host() or X509_VERIFY_PARAM_add1_host().
138 To obtain all names start with B<n> = 0 and increment B<n> as long as no NULL
141 X509_VERIFY_PARAM_set1_host() sets the expected DNS hostname to
142 B<name> clearing any previously specified hostname. If
143 B<name> is NULL, or empty the list of hostnames is cleared, and
144 name checks are not performed on the peer certificate. If B<name>
145 is NUL-terminated, B<namelen> may be zero, otherwise B<namelen>
146 must be set to the length of B<name>.
148 When a hostname is specified,
149 certificate verification automatically invokes L<X509_check_host(3)>
150 with flags equal to the B<flags> argument given to
151 X509_VERIFY_PARAM_set_hostflags() (default zero). Applications
152 are strongly advised to use this interface in preference to explicitly
153 calling L<X509_check_host(3)>, hostname checks may be out of scope
154 with the DANE-EE(3) certificate usage, and the internal check will
155 be suppressed as appropriate when DANE verification is enabled.
157 When the subject CommonName will not be ignored, whether as a result of the
158 B<X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT> host flag, or because no DNS subject
159 alternative names are present in the certificate, any DNS name constraints in
160 issuer certificates apply to the subject CommonName as well as the subject
161 alternative name extension.
163 When the subject CommonName will be ignored, whether as a result of the
164 B<X509_CHECK_FLAG_NEVER_CHECK_SUBJECT> host flag, or because some DNS subject
165 alternative names are present in the certificate, DNS name constraints in
166 issuer certificates will not be applied to the subject DN.
167 As described in X509_check_host(3) the B<X509_CHECK_FLAG_NEVER_CHECK_SUBJECT>
168 flag takes precedence over the B<X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT> flag.
170 X509_VERIFY_PARAM_get_hostflags() returns any host flags previously set via a
171 call to X509_VERIFY_PARAM_set_hostflags().
173 X509_VERIFY_PARAM_add1_host() adds B<name> as an additional reference
174 identifier that can match the peer's certificate. Any previous names
175 set via X509_VERIFY_PARAM_set1_host() or X509_VERIFY_PARAM_add1_host()
176 are retained, no change is made if B<name> is NULL or empty. When
177 multiple names are configured, the peer is considered verified when
180 X509_VERIFY_PARAM_get0_peername() returns the DNS hostname or subject
181 CommonName from the peer certificate that matched one of the reference
182 identifiers. When wildcard matching is not disabled, or when a
183 reference identifier specifies a parent domain (starts with ".")
184 rather than a hostname, the peer name may be a wildcard name or a
185 sub-domain of the reference identifier respectively. The return
186 string is allocated by the library and is no longer valid once the
187 associated B<param> argument is freed. Applications must not free
190 X509_VERIFY_PARAM_get0_email() returns the expected RFC822 email address.
192 X509_VERIFY_PARAM_set1_email() sets the expected RFC822 email address to
193 B<email>. If B<email> is NUL-terminated, B<emaillen> may be zero, otherwise
194 B<emaillen> must be set to the length of B<email>. When an email address
195 is specified, certificate verification automatically invokes
196 L<X509_check_email(3)>.
198 X509_VERIFY_PARAM_get1_ip_asc() returns the expected IP address as a string.
199 The caller is responsible for freeing it.
201 X509_VERIFY_PARAM_set1_ip() sets the expected IP address to B<ip>.
202 The B<ip> argument is in binary format, in network byte-order and
203 B<iplen> must be set to 4 for IPv4 and 16 for IPv6. When an IP
204 address is specified, certificate verification automatically invokes
207 X509_VERIFY_PARAM_set1_ip_asc() sets the expected IP address to
208 B<ipasc>. The B<ipasc> argument is a NUL-terminal ASCII string:
209 dotted decimal quad for IPv4 and colon-separated hexadecimal for
210 IPv6. The condensed "::" notation is supported for IPv6 addresses.
214 X509_VERIFY_PARAM_set_flags(), X509_VERIFY_PARAM_clear_flags(),
215 X509_VERIFY_PARAM_set_inh_flags(),
216 X509_VERIFY_PARAM_set_purpose(), X509_VERIFY_PARAM_set_trust(),
217 X509_VERIFY_PARAM_add0_policy() X509_VERIFY_PARAM_set1_policies(),
218 X509_VERIFY_PARAM_set1_host(), X509_VERIFY_PARAM_add1_host(),
219 X509_VERIFY_PARAM_set1_email(), X509_VERIFY_PARAM_set1_ip() and
220 X509_VERIFY_PARAM_set1_ip_asc() return 1 for success and 0 for
223 X509_VERIFY_PARAM_get0_host(), X509_VERIFY_PARAM_get0_email(), and
224 X509_VERIFY_PARAM_get1_ip_asc(), return the string pointers specified above
225 or NULL if the respective value has not been set or on error.
227 X509_VERIFY_PARAM_get_flags() returns the current verification flags.
229 X509_VERIFY_PARAM_get_hostflags() returns any current host flags.
231 X509_VERIFY_PARAM_get_inh_flags() returns the current inheritance flags.
233 X509_VERIFY_PARAM_set_time() and X509_VERIFY_PARAM_set_depth() do not return
236 X509_VERIFY_PARAM_get_depth() returns the current verification depth.
238 X509_VERIFY_PARAM_get_auth_level() returns the current authentication security
241 =head1 VERIFICATION FLAGS
243 The verification flags consists of zero or more of the following flags
246 B<X509_V_FLAG_CRL_CHECK> enables CRL checking for the certificate chain leaf
247 certificate. An error occurs if a suitable CRL cannot be found.
249 B<X509_V_FLAG_CRL_CHECK_ALL> enables CRL checking for the entire certificate
252 B<X509_V_FLAG_IGNORE_CRITICAL> disables critical extension checking. By default
253 any unhandled critical extensions in certificates or (if checked) CRLs result
254 in a fatal error. If this flag is set unhandled critical extensions are
255 ignored. B<WARNING> setting this option for anything other than debugging
256 purposes can be a security risk. Finer control over which extensions are
257 supported can be performed in the verification callback.
259 The B<X509_V_FLAG_X509_STRICT> flag disables workarounds for some broken
260 certificates and makes the verification strictly apply B<X509> rules.
262 B<X509_V_FLAG_ALLOW_PROXY_CERTS> enables proxy certificate verification.
264 B<X509_V_FLAG_POLICY_CHECK> enables certificate policy checking, by default
265 no policy checking is performed. Additional information is sent to the
266 verification callback relating to policy checking.
268 B<X509_V_FLAG_EXPLICIT_POLICY>, B<X509_V_FLAG_INHIBIT_ANY> and
269 B<X509_V_FLAG_INHIBIT_MAP> set the B<require explicit policy>, B<inhibit any
270 policy> and B<inhibit policy mapping> flags respectively as defined in
271 B<RFC3280>. Policy checking is automatically enabled if any of these flags
274 If B<X509_V_FLAG_NOTIFY_POLICY> is set and the policy checking is successful
275 a special status code is set to the verification callback. This permits it
276 to examine the valid policy tree and perform additional checks or simply
277 log it for debugging purposes.
279 By default some additional features such as indirect CRLs and CRLs signed by
280 different keys are disabled. If B<X509_V_FLAG_EXTENDED_CRL_SUPPORT> is set
283 If B<X509_V_FLAG_USE_DELTAS> is set delta CRLs (if present) are used to
284 determine certificate status. If not set deltas are ignored.
286 B<X509_V_FLAG_CHECK_SS_SIGNATURE> requests checking the signature of
287 the last certificate in a chain if the certificate is supposedly self-signed.
288 This is prohibited and will result in an error if it is a non-conforming CA
289 certificate with key usage restrictions not including the I<keyCertSign> bit.
290 By default this check is disabled because it doesn't
291 add any additional security but in some cases applications might want to
292 check the signature anyway. A side effect of not checking the self-signature
293 of such a certificate is that disabled or unsupported message digests used for
294 the signature are not treated as fatal errors.
296 When B<X509_V_FLAG_TRUSTED_FIRST> is set, which is always the case since
297 OpenSSL 1.1.0, construction of the certificate chain
298 in L<X509_verify_cert(3)> searches the trust store for issuer certificates
299 before searching the provided untrusted certificates.
300 Local issuer certificates are often more likely to satisfy local security
301 requirements and lead to a locally trusted root.
302 This is especially important when some certificates in the trust store have
303 explicit trust settings (see "TRUST SETTINGS" in L<openssl-x509(1)>).
305 The B<X509_V_FLAG_NO_ALT_CHAINS> flag could have been used before OpenSSL 1.1.0
306 to suppress checking for alternative chains.
307 By default, unless B<X509_V_FLAG_TRUSTED_FIRST> is set, when building a
308 certificate chain, if the first certificate chain found is not trusted, then
309 OpenSSL will attempt to replace untrusted certificates supplied by the peer
310 with certificates from the trust store to see if an alternative chain can be
311 found that is trusted.
312 As of OpenSSL 1.1.0, with B<X509_V_FLAG_TRUSTED_FIRST> always set, this option
315 The B<X509_V_FLAG_PARTIAL_CHAIN> flag causes non-self-signed certificates in the
316 trust store to be treated as trust anchors, in the same way as self-signed
317 root CA certificates.
318 This makes it possible to trust self-issued certificates as well as certificates
319 issued by an intermediate CA without having to trust their ancestor root CA.
320 With OpenSSL 1.1.0 and later and B<X509_V_FLAG_PARTIAL_CHAIN> set, chain
321 construction stops as soon as the first certificate contained in the trust store
322 is added to the chain, whether that certificate is a self-signed "root"
323 certificate or a not self-signed "intermediate" or self-issued certificate.
324 Thus, when an intermediate certificate is found in the trust store, the
325 verified chain passed to callbacks may be shorter than it otherwise would
326 be without the B<X509_V_FLAG_PARTIAL_CHAIN> flag.
328 The B<X509_V_FLAG_NO_CHECK_TIME> flag suppresses checking the validity period
329 of certificates and CRLs against the current time. If X509_VERIFY_PARAM_set_time()
330 is used to specify a verification time, the check is not suppressed.
332 =head1 INHERITANCE FLAGS
334 These flags specify how parameters are "inherited" from one structure to
337 If B<X509_VP_FLAG_ONCE> is set then the current setting is zeroed
340 If B<X509_VP_FLAG_LOCKED> is set then no values are copied. This overrides
341 all of the following flags.
343 If B<X509_VP_FLAG_DEFAULT> is set then anything set in the source is copied
344 to the destination. Effectively the values in "to" become default values
345 which will be used only if nothing new is set in "from". This is the
348 If B<X509_VP_FLAG_OVERWRITE> is set then all value are copied across whether
349 they are set or not. Flags is still Ored though.
351 If B<X509_VP_FLAG_RESET_FLAGS> is set then the flags value is copied instead
356 The above functions should be used to manipulate verification parameters
357 instead of functions which work in specific structures such as
358 X509_STORE_CTX_set_flags() which are likely to be deprecated in a future
363 Delta CRL checking is currently primitive. Only a single delta can be used and
364 (partly due to limitations of B<X509_STORE>) constructed CRLs are not
367 If CRLs checking is enable CRLs are expected to be available in the
368 corresponding B<X509_STORE> structure. No attempt is made to download
369 CRLs from the CRL distribution points extension.
373 Enable CRL checking when performing certificate verification during SSL
374 connections associated with an B<SSL_CTX> structure B<ctx>:
376 X509_VERIFY_PARAM *param;
378 param = X509_VERIFY_PARAM_new();
379 X509_VERIFY_PARAM_set_flags(param, X509_V_FLAG_CRL_CHECK);
380 SSL_CTX_set1_param(ctx, param);
381 X509_VERIFY_PARAM_free(param);
385 L<X509_verify_cert(3)>,
386 L<X509_check_host(3)>,
387 L<X509_check_email(3)>,
393 The B<X509_V_FLAG_NO_ALT_CHAINS> flag was added in OpenSSL 1.1.0.
394 The flag B<X509_V_FLAG_CB_ISSUER_CHECK> was deprecated in OpenSSL 1.1.0
397 The X509_VERIFY_PARAM_get_hostflags() function was added in OpenSSL 1.1.0i.
399 The X509_VERIFY_PARAM_get0_host(), X509_VERIFY_PARAM_get0_email(),
400 and X509_VERIFY_PARAM_get1_ip_asc() functions were added in OpenSSL 3.0.
404 Copyright 2009-2022 The OpenSSL Project Authors. All Rights Reserved.
406 Licensed under the Apache License 2.0 (the "License"). You may not use
407 this file except in compliance with the License. You can obtain a copy
408 in the file LICENSE in the source distribution or at
409 L<https://www.openssl.org/source/license.html>.