xref: /openssl/doc/man3/X509_STORE_CTX_new.pod (revision a82c2bf5) 
1=pod
2
3=head1 NAME
4
5X509_STORE_CTX_new_ex, X509_STORE_CTX_new, X509_STORE_CTX_cleanup,
6X509_STORE_CTX_free, X509_STORE_CTX_init,
7X509_STORE_CTX_init_rpk,
8X509_STORE_CTX_set0_trusted_stack,
9X509_STORE_CTX_set_cert, X509_STORE_CTX_set0_crls,
10X509_STORE_CTX_set0_rpk,
11X509_STORE_CTX_get0_param, X509_STORE_CTX_set0_param,
12X509_STORE_CTX_get0_untrusted, X509_STORE_CTX_set0_untrusted,
13X509_STORE_CTX_get_num_untrusted,
14X509_STORE_CTX_get0_chain, X509_STORE_CTX_set0_verified_chain,
15X509_STORE_CTX_get0_rpk,
16X509_STORE_CTX_set_default,
17X509_STORE_CTX_set_verify,
18X509_STORE_CTX_verify_fn,
19X509_STORE_CTX_set_purpose,
20X509_STORE_CTX_set_trust,
21X509_STORE_CTX_purpose_inherit
22- X509_STORE_CTX initialisation
23
24=head1 SYNOPSIS
25
26 #include <openssl/x509_vfy.h>
27
28 X509_STORE_CTX *X509_STORE_CTX_new_ex(OSSL_LIB_CTX *libctx, const char *propq);
29 X509_STORE_CTX *X509_STORE_CTX_new(void);
30 void X509_STORE_CTX_cleanup(X509_STORE_CTX *ctx);
31 void X509_STORE_CTX_free(X509_STORE_CTX *ctx);
32
33 int X509_STORE_CTX_init(X509_STORE_CTX *ctx, X509_STORE *trust_store,
34                         X509 *target, STACK_OF(X509) *untrusted);
35 int X509_STORE_CTX_init_rpk(X509_STORE_CTX *ctx, X509_STORE *trust_store,
36                             EVP_PKEY *rpk);
37
38 void X509_STORE_CTX_set0_trusted_stack(X509_STORE_CTX *ctx, STACK_OF(X509) *sk);
39
40 void X509_STORE_CTX_set_cert(X509_STORE_CTX *ctx, X509 *target);
41 void X509_STORE_CTX_set0_crls(X509_STORE_CTX *ctx, STACK_OF(X509_CRL) *sk);
42 void X509_STORE_CTX_set0_rpk(X509_STORE_CTX *ctx, EVP_PKEY *target);
43
44 X509_VERIFY_PARAM *X509_STORE_CTX_get0_param(const X509_STORE_CTX *ctx);
45 void X509_STORE_CTX_set0_param(X509_STORE_CTX *ctx, X509_VERIFY_PARAM *param);
46
47 STACK_OF(X509)* X509_STORE_CTX_get0_untrusted(const X509_STORE_CTX *ctx);
48 void X509_STORE_CTX_set0_untrusted(X509_STORE_CTX *ctx, STACK_OF(X509) *sk);
49
50 int X509_STORE_CTX_get_num_untrusted(const X509_STORE_CTX *ctx);
51 STACK_OF(X509) *X509_STORE_CTX_get0_chain(const X509_STORE_CTX *ctx);
52 void X509_STORE_CTX_set0_verified_chain(X509_STORE_CTX *ctx, STACK_OF(X509) *chain);
53 EVP_PKEY *X509_STORE_CTX_get0_rpk(const X509_STORE_CTX *ctx);
54
55 int X509_STORE_CTX_set_default(X509_STORE_CTX *ctx, const char *name);
56 typedef int (*X509_STORE_CTX_verify_fn)(X509_STORE_CTX *);
57 void X509_STORE_CTX_set_verify(X509_STORE_CTX *ctx, X509_STORE_CTX_verify_fn verify);
58
59 int X509_STORE_CTX_set_purpose(X509_STORE_CTX *ctx, int purpose);
60 int X509_STORE_CTX_set_trust(X509_STORE_CTX *ctx, int trust);
61 int X509_STORE_CTX_purpose_inherit(X509_STORE_CTX *ctx, int def_purpose,
62                                    int purpose, int trust);
63
64=head1 DESCRIPTION
65
66These functions initialise an B<X509_STORE_CTX> structure for subsequent use
67by L<X509_verify_cert(3)> or L<X509_STORE_CTX_verify(3)>.
68
69X509_STORE_CTX_new_ex() returns a newly initialised B<X509_STORE_CTX>
70structure associated with the specified library context I<libctx> and property
71query string I<propq>. Any cryptographic algorithms fetched while performing
72processing with the X509_STORE_CTX will use that library context and property
73query string.
74
75X509_STORE_CTX_new() is the same as X509_STORE_CTX_new_ex() except that
76the default library context and a NULL property query string are used.
77
78X509_STORE_CTX_cleanup() internally cleans up an B<X509_STORE_CTX> structure.
79It is used by X509_STORE_CTX_init() and X509_STORE_CTX_free().
80
81X509_STORE_CTX_free() completely frees up I<ctx>. After this call I<ctx>
82is no longer valid.
83If I<ctx> is NULL nothing is done.
84
85X509_STORE_CTX_init() sets up I<ctx> for a subsequent verification operation.
86
87X509_STORE_CTX_init() initializes the internal state and resources of the
88given I<ctx>. Among others, it sets the verification parameters associcated
89with the method name C<default>, which includes the C<any> purpose,
90and takes over callback function pointers from I<trust_store> (unless NULL).
91It must be called before each call to L<X509_verify_cert(3)> or
92L<X509_STORE_CTX_verify(3)>, i.e., a context is only good for one verification.
93If you want to verify a further certificate or chain with the same I<ctx>
94then you must call X509_STORE_CTX_init() again.
95The trusted certificate store is set to I<trust_store> of type B<X509_STORE>.
96This may be NULL because there are no trusted certificates or because
97they are provided simply as a list using X509_STORE_CTX_set0_trusted_stack().
98The certificate to be verified is set to I<target>,
99and a list of additional certificates may be provided in I<untrusted>,
100which will be untrusted but may be used to build the chain.
101The I<target> certificate is not copied (its reference count is not updated),
102and the caller must not free it before verification is complete.
103Each of the I<trust_store>, I<target> and I<untrusted> parameters can be NULL.
104Yet note that L<X509_verify_cert(3)> and L<X509_STORE_CTX_verify(3)>
105will need a verification target.
106This can also be set using X509_STORE_CTX_set_cert().
107For L<X509_STORE_CTX_verify(3)>, which takes by default the first element of the
108list of untrusted certificates as its verification target,
109this can be also set indirectly using X509_STORE_CTX_set0_untrusted().
110
111X509_STORE_CTX_init_rpk() sets up I<ctx> for a subsequent verification
112operation for the I<target> raw public key.
113It behaves similarly to X509_STORE_CTX_init().
114The I<target> raw public key can also be supplied separately, via
115X509_STORE_CTX_set0_rpk().
116The I<target> public key is not copied (its reference count is not updated),
117and the caller must not free it before verification is complete.
118
119X509_STORE_CTX_set0_trusted_stack() sets the set of trusted certificates of
120I<ctx> to I<sk>. This is an alternative way of specifying trusted certificates
121instead of using an B<X509_STORE> where its complexity is not needed
122or to make sure that only the given set I<sk> of certificates are trusted.
123
124X509_STORE_CTX_set_cert() sets the target certificate to be verified in I<ctx>
125to I<target>.
126The target certificate is not copied (its reference count is not updated),
127and the caller must not free it before verification is complete.
128
129X509_STORE_CTX_set0_rpk() sets the target raw public key to be verified in I<ctx>
130to I<target>, a non-NULL raw public key preempts any target certificate, which
131is then ignored.
132The I<target> public key is not copied (its reference count is not updated),
133and the caller must not free it before verification is complete.
134
135X509_STORE_CTX_set0_verified_chain() sets the validated chain to I<chain>.
136Ownership of the chain is transferred to I<ctx>,
137and so it should not be free'd by the caller.
138
139X509_STORE_CTX_get0_chain() returns the internal pointer used by the
140I<ctx> that contains the constructed (output) chain.
141
142X509_STORE_CTX_get0_rpk() returns the internal pointer used by the
143I<ctx> that contains the raw public key.
144
145X509_STORE_CTX_set0_crls() sets a set of CRLs to use to aid certificate
146verification to I<sk>. These CRLs will only be used if CRL verification is
147enabled in the associated B<X509_VERIFY_PARAM> structure. This might be
148used where additional "useful" CRLs are supplied as part of a protocol,
149for example in a PKCS#7 structure.
150
151X509_STORE_CTX_get0_param() retrieves an internal pointer
152to the verification parameters associated with I<ctx>.
153
154X509_STORE_CTX_set0_param() sets the internal verification parameter pointer
155to I<param>. After this call B<param> should not be used.
156
157X509_STORE_CTX_get0_untrusted() retrieves an internal pointer to the
158stack of untrusted certificates associated with I<ctx>.
159
160X509_STORE_CTX_set0_untrusted() sets the internal pointer to the stack
161of untrusted certificates associated with I<ctx> to I<sk>.
162X509_STORE_CTX_verify() will take the first element, if any,
163as its default target if the target certificate is not set explicitly.
164
165X509_STORE_CTX_get_num_untrusted() returns the number of untrusted certificates
166that were used in building the chain.
167This is can be used after calling L<X509_verify_cert(3)> and similar functions.
168With L<X509_STORE_CTX_verify(3)>, this does not count the first chain element.
169
170X509_STORE_CTX_get0_chain() returns the internal pointer used by the
171I<ctx> that contains the validated chain.
172
173Details of the chain building and checking process are described in
174L<openssl-verification-options(1)/Certification Path Building> and
175L<openssl-verification-options(1)/Certification Path Validation>.
176
177X509_STORE_CTX_set0_verified_chain() sets the validated chain used
178by I<ctx> to be I<chain>.
179Ownership of the chain is transferred to I<ctx>,
180and so it should not be free'd by the caller.
181
182X509_STORE_CTX_set_default() looks up and sets the default verification method.
183This uses the function X509_VERIFY_PARAM_lookup() to find
184the set of parameters associated with the given verification method I<name>.
185Among others, the parameters determine the trust model and verification purpose.
186More detail, including the list of currently predefined methods,
187is described for the B<-verify_name> command-line option
188in L<openssl-verification-options(1)/Verification Options>.
189
190X509_STORE_CTX_set_verify() provides the capability for overriding the default
191verify function. This function is responsible for verifying chain signatures and
192expiration times.
193
194A verify function is defined as an X509_STORE_CTX_verify type which has the
195following signature:
196
197 int (*verify)(X509_STORE_CTX *);
198
199This function should receive the current X509_STORE_CTX as a parameter and
200return 1 on success or 0 on failure.
201
202X509 certificates may contain information about what purposes keys contained
203within them can be used for. For example "TLS WWW Server Authentication" or
204"Email Protection". This "key usage" information is held internally to the
205certificate itself. In addition the trust store containing trusted certificates
206can declare what purposes we trust different certificates for. This "trust"
207information is not held within the certificate itself but is "meta" information
208held alongside it. This "meta" information is associated with the certificate
209after it is issued and could be determined by a system administrator. For
210example a certificate might declare that it is suitable for use for both
211"TLS WWW Server Authentication" and "TLS Client Authentication", but a system
212administrator might only trust it for the former. An X.509 certificate extension
213exists that can record extended key usage information to supplement the purpose
214information described above. This extended mechanism is arbitrarily extensible
215and not well suited for a generic library API; applications that need to
216validate extended key usage information in certificates will need to define a
217custom "purpose" (see below) or supply a nondefault verification callback
218(L<X509_STORE_set_verify_cb_func(3)>).
219
220X509_STORE_CTX_set_purpose() sets the purpose for the target certificate being
221verified in the I<ctx>. Built-in available values for the I<purpose> argument
222are B<X509_PURPOSE_SSL_CLIENT>, B<X509_PURPOSE_SSL_SERVER>,
223B<X509_PURPOSE_NS_SSL_SERVER>, B<X509_PURPOSE_SMIME_SIGN>,
224B<X509_PURPOSE_SMIME_ENCRYPT>, B<X509_PURPOSE_CRL_SIGN>, B<X509_PURPOSE_ANY>,
225B<X509_PURPOSE_OCSP_HELPER>, B<X509_PURPOSE_TIMESTAMP_SIGN> and
226B<X509_PURPOSE_CODE_SIGN>.  It is also
227possible to create a custom purpose value. Setting a purpose requests that
228the key usage and extended key usage (EKU) extensions optionally declared within
229the certificate and its chain are verified to be consistent with that purpose.
230For SSL client, SSL server, and S/MIME purposes, the EKU is checked also for the
231CA certificates along the chain, including any given trust anchor certificate.
232Potentially also further checks are done (depending on the purpose given).
233Every purpose also has an associated default trust value, which will also be set
234at the same time. During verification, this trust setting will be verified
235to check whether it is consistent with the trust set by the system administrator
236for certificates in the chain.
237
238X509_STORE_CTX_set_trust() sets the trust value for the target certificate
239being verified in the I<ctx>. Built-in available values for the I<trust>
240argument are B<X509_TRUST_COMPAT>, B<X509_TRUST_SSL_CLIENT>,
241B<X509_TRUST_SSL_SERVER>, B<X509_TRUST_EMAIL>, B<X509_TRUST_OBJECT_SIGN>,
242B<X509_TRUST_OCSP_SIGN>, B<X509_TRUST_OCSP_REQUEST> and B<X509_TRUST_TSA>. It is
243also possible to create a custom trust value. Since X509_STORE_CTX_set_purpose()
244also sets the trust value it is normally sufficient to only call that function.
245If both are called then X509_STORE_CTX_set_trust() should be called after
246X509_STORE_CTX_set_purpose() since the trust setting of the last call will be
247used.
248
249It should not normally be necessary for end user applications to call
250X509_STORE_CTX_purpose_inherit() directly. Typically applications should call
251X509_STORE_CTX_set_purpose() or X509_STORE_CTX_set_trust() instead. Using this
252function it is possible to set the purpose and trust values for the I<ctx> at
253the same time.
254Both I<ctx> and its internal verification parameter pointer must not be NULL.
255The I<def_purpose> and I<purpose> arguments can have the same
256purpose values as described for X509_STORE_CTX_set_purpose() above. The I<trust>
257argument can have the same trust values as described in
258X509_STORE_CTX_set_trust() above. Any of the I<def_purpose>, I<purpose> or
259I<trust> values may also have the value 0 to indicate that the supplied
260parameter should be ignored. After calling this function the purpose to be used
261for verification is set from the I<purpose> argument unless the purpose was
262already set in I<ctx> before, and the trust is set from the I<trust> argument
263unless the trust was already set in I<ctx> before.
264If I<trust> is 0 then the trust value will be set from
265the default trust value for I<purpose>. If the default trust value for the
266purpose is I<X509_TRUST_DEFAULT> and I<trust> is 0 then the default trust value
267associated with the I<def_purpose> value is used for the trust setting instead.
268
269=head1 NOTES
270
271The certificates and CRLs in a store are used internally and should B<not>
272be freed up until after the associated B<X509_STORE_CTX> is freed.
273
274=head1 BUGS
275
276The certificates and CRLs in a context are used internally and should B<not>
277be freed up until after the associated B<X509_STORE_CTX> is freed. Copies
278should be made or reference counts increased instead.
279
280=head1 RETURN VALUES
281
282X509_STORE_CTX_new() returns a newly allocated context or NULL if an
283error occurred.
284
285X509_STORE_CTX_init() and X509_STORE_CTX_init_rpk() return 1 for success
286or 0 if an error occurred.
287
288X509_STORE_CTX_get0_param() returns a pointer to an B<X509_VERIFY_PARAM>
289structure or NULL if an error occurred.
290
291X509_STORE_CTX_get0_rpk() returns a pointer to an B<EVP_PKEY> structure if
292present, or NULL if absent.
293
294X509_STORE_CTX_cleanup(), X509_STORE_CTX_free(),
295X509_STORE_CTX_set0_trusted_stack(),
296X509_STORE_CTX_set_cert(),
297X509_STORE_CTX_set0_crls() and X509_STORE_CTX_set0_param() do not return
298values.
299
300X509_STORE_CTX_set_default() returns 1 for success or 0 if an error occurred.
301
302X509_STORE_CTX_get_num_untrusted() returns the number of untrusted certificates
303used.
304
305=head1 SEE ALSO
306
307L<X509_verify_cert(3)>, L<X509_STORE_CTX_verify(3)>,
308L<X509_VERIFY_PARAM_set_flags(3)>
309
310=head1 HISTORY
311
312The X509_STORE_CTX_set0_crls() function was added in OpenSSL 1.0.0.
313The X509_STORE_CTX_get_num_untrusted() function was added in OpenSSL 1.1.0.
314The X509_STORE_CTX_new_ex() function was added in OpenSSL 3.0.
315The X509_STORE_CTX_init_rpk(), X509_STORE_CTX_get0_rpk(), and
316X509_STORE_CTX_set0_rpk() functions were added in OpenSSL 3.2.
317
318There is no need to call X509_STORE_CTX_cleanup() explicitly since OpenSSL 3.0.
319
320=head1 COPYRIGHT
321
322Copyright 2009-2024 The OpenSSL Project Authors. All Rights Reserved.
323
324Licensed under the Apache License 2.0 (the "License").  You may not use
325this file except in compliance with the License.  You can obtain a copy
326in the file LICENSE in the source distribution or at
327L<https://www.openssl.org/source/license.html>.
328
329=cut
330