xref: /openssl/doc/man3/X509_STORE_CTX_new.pod (revision 178696d6) 
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, X509_STORE_CTX_set0_trusted_stack,
7X509_STORE_CTX_set_cert, X509_STORE_CTX_set0_crls,
8X509_STORE_CTX_get0_param, X509_STORE_CTX_set0_param,
9X509_STORE_CTX_get0_untrusted, X509_STORE_CTX_set0_untrusted,
10X509_STORE_CTX_get_num_untrusted,
11X509_STORE_CTX_get0_chain, X509_STORE_CTX_set0_verified_chain,
12X509_STORE_CTX_set_default,
13X509_STORE_CTX_set_verify,
14X509_STORE_CTX_verify_fn,
15X509_STORE_CTX_set_purpose,
16X509_STORE_CTX_set_trust,
17X509_STORE_CTX_purpose_inherit
18- X509_STORE_CTX initialisation
19
20=head1 SYNOPSIS
21
22 #include <openssl/x509_vfy.h>
23
24 X509_STORE_CTX *X509_STORE_CTX_new_ex(OSSL_LIB_CTX *libctx, const char *propq);
25 X509_STORE_CTX *X509_STORE_CTX_new(void);
26 void X509_STORE_CTX_cleanup(X509_STORE_CTX *ctx);
27 void X509_STORE_CTX_free(X509_STORE_CTX *ctx);
28
29 int X509_STORE_CTX_init(X509_STORE_CTX *ctx, X509_STORE *trust_store,
30                         X509 *target, STACK_OF(X509) *untrusted);
31
32 void X509_STORE_CTX_set0_trusted_stack(X509_STORE_CTX *ctx, STACK_OF(X509) *sk);
33
34 void X509_STORE_CTX_set_cert(X509_STORE_CTX *ctx, X509 *target);
35 void X509_STORE_CTX_set0_crls(X509_STORE_CTX *ctx, STACK_OF(X509_CRL) *sk);
36
37 X509_VERIFY_PARAM *X509_STORE_CTX_get0_param(const X509_STORE_CTX *ctx);
38 void X509_STORE_CTX_set0_param(X509_STORE_CTX *ctx, X509_VERIFY_PARAM *param);
39
40 STACK_OF(X509)* X509_STORE_CTX_get0_untrusted(const X509_STORE_CTX *ctx);
41 void X509_STORE_CTX_set0_untrusted(X509_STORE_CTX *ctx, STACK_OF(X509) *sk);
42
43 int X509_STORE_CTX_get_num_untrusted(const X509_STORE_CTX *ctx);
44 STACK_OF(X509) *X509_STORE_CTX_get0_chain(const X509_STORE_CTX *ctx);
45 void X509_STORE_CTX_set0_verified_chain(X509_STORE_CTX *ctx, STACK_OF(X509) *chain);
46
47 int X509_STORE_CTX_set_default(X509_STORE_CTX *ctx, const char *name);
48 typedef int (*X509_STORE_CTX_verify_fn)(X509_STORE_CTX *);
49 void X509_STORE_CTX_set_verify(X509_STORE_CTX *ctx, X509_STORE_CTX_verify_fn verify);
50
51 int X509_STORE_CTX_set_purpose(X509_STORE_CTX *ctx, int purpose);
52 int X509_STORE_CTX_set_trust(X509_STORE_CTX *ctx, int trust);
53 int X509_STORE_CTX_purpose_inherit(X509_STORE_CTX *ctx, int def_purpose,
54                                    int purpose, int trust);
55
56=head1 DESCRIPTION
57
58These functions initialise an B<X509_STORE_CTX> structure for subsequent use
59by L<X509_verify_cert(3)> or L<X509_STORE_CTX_verify(3)>.
60
61X509_STORE_CTX_new_ex() returns a newly initialised B<X509_STORE_CTX>
62structure associated with the specified library context I<libctx> and property
63query string I<propq>. Any cryptographic algorithms fetched while performing
64processing with the X509_STORE_CTX will use that library context and property
65query string.
66
67X509_STORE_CTX_new() is the same as X509_STORE_CTX_new_ex() except that
68the default library context and a NULL property query string are used.
69
70X509_STORE_CTX_cleanup() internally cleans up an B<X509_STORE_CTX> structure.
71It is used by X509_STORE_CTX_init() and X509_STORE_CTX_free().
72
73X509_STORE_CTX_free() completely frees up I<ctx>. After this call I<ctx>
74is no longer valid.
75If I<ctx> is NULL nothing is done.
76
77X509_STORE_CTX_init() sets up I<ctx> for a subsequent verification operation.
78It must be called before each call to L<X509_verify_cert(3)> or
79L<X509_STORE_CTX_verify(3)>, i.e., a context is only good for one verification.
80If you want to verify a further certificate or chain with the same I<ctx>
81then you must call X509_STORE_CTX_init() again.
82The trusted certificate store is set to I<trust_store> of type B<X509_STORE>.
83This may be NULL because there are no trusted certificates or because
84they are provided simply as a list using X509_STORE_CTX_set0_trusted_stack().
85The certificate to be verified is set to I<target>,
86and a list of additional certificates may be provided in I<untrusted>,
87which will be untrusted but may be used to build the chain.
88Each of the I<trust_store>, I<target> and I<untrusted> parameters can be NULL.
89Yet note that L<X509_verify_cert(3)> and L<X509_STORE_CTX_verify(3)>
90will need a verification target.
91This can also be set using X509_STORE_CTX_set_cert().
92For L<X509_STORE_CTX_verify(3)>, which takes by default the first element of the
93list of untrusted certificates as its verification target,
94this can be also set indirectly using X509_STORE_CTX_set0_untrusted().
95
96X509_STORE_CTX_set0_trusted_stack() sets the set of trusted certificates of
97I<ctx> to I<sk>. This is an alternative way of specifying trusted certificates
98instead of using an B<X509_STORE> where its complexity is not needed
99or to make sure that only the given set I<sk> of certificates are trusted.
100
101X509_STORE_CTX_set_cert() sets the target certificate to be verified in I<ctx>
102to I<target>.
103
104X509_STORE_CTX_set0_verified_chain() sets the validated chain to I<chain>.
105Ownership of the chain is transferred to I<ctx>,
106and so it should not be free'd by the caller.
107
108X509_STORE_CTX_get0_chain() returns the internal pointer used by the
109I<ctx> that contains the constructed (output) chain.
110
111X509_STORE_CTX_set0_crls() sets a set of CRLs to use to aid certificate
112verification to I<sk>. These CRLs will only be used if CRL verification is
113enabled in the associated B<X509_VERIFY_PARAM> structure. This might be
114used where additional "useful" CRLs are supplied as part of a protocol,
115for example in a PKCS#7 structure.
116
117X509_STORE_CTX_get0_param() retrieves an internal pointer
118to the verification parameters associated with I<ctx>.
119
120X509_STORE_CTX_set0_param() sets the internal verification parameter pointer
121to I<param>. After this call B<param> should not be used.
122
123X509_STORE_CTX_get0_untrusted() retrieves an internal pointer to the
124stack of untrusted certificates associated with I<ctx>.
125
126X509_STORE_CTX_set0_untrusted() sets the internal pointer to the stack
127of untrusted certificates associated with I<ctx> to I<sk>.
128X509_STORE_CTX_verify() will take the first element, if any,
129as its default target if the target certificate is not set explicitly.
130
131X509_STORE_CTX_get_num_untrusted() returns the number of untrusted certificates
132that were used in building the chain.
133This is can be used after calling L<X509_verify_cert(3)> and similar functions.
134With L<X509_STORE_CTX_verify(3)>, this does not count the first chain element.
135
136X509_STORE_CTX_get0_chain() returns the internal pointer used by the
137I<ctx> that contains the validated chain.
138
139Details of the chain building and checking process are described in
140L<openssl-verification-options(1)/Certification Path Building> and
141L<openssl-verification-options(1)/Certification Path Validation>.
142
143X509_STORE_CTX_set0_verified_chain() sets the validated chain used
144by I<ctx> to be I<chain>.
145Ownership of the chain is transferred to I<ctx>,
146and so it should not be free'd by the caller.
147
148X509_STORE_CTX_set_default() looks up and sets the default verification
149method to I<name>. This uses the function X509_VERIFY_PARAM_lookup() to
150find an appropriate set of parameters from the purpose identifier I<name>.
151Currently defined purposes are C<sslclient>, C<sslserver>, C<nssslserver>,
152C<smimesign>, C<smimeencrypt>, C<crlsign>, C<ocsphelper>, C<timestampsign>,
153and C<any>.
154
155X509_STORE_CTX_set_verify() provides the capability for overriding the default
156verify function. This function is responsible for verifying chain signatures and
157expiration times.
158
159A verify function is defined as an X509_STORE_CTX_verify type which has the
160following signature:
161
162 int (*verify)(X509_STORE_CTX *);
163
164This function should receive the current X509_STORE_CTX as a parameter and
165return 1 on success or 0 on failure.
166
167X509 certificates may contain information about what purposes keys contained
168within them can be used for. For example "TLS WWW Server Authentication" or
169"Email Protection". This "key usage" information is held internally to the
170certificate itself. In addition the trust store containing trusted certificates
171can declare what purposes we trust different certificates for. This "trust"
172information is not held within the certificate itself but is "meta" information
173held alongside it. This "meta" information is associated with the certificate
174after it is issued and could be determined by a system administrator. For
175example a certificate might declare that it is suitable for use for both
176"TLS WWW Server Authentication" and "TLS Client Authentication", but a system
177administrator might only trust it for the former. An X.509 certificate extension
178exists that can record extended key usage information to supplement the purpose
179information described above. This extended mechanism is arbitrarily extensible
180and not well suited for a generic library API; applications that need to
181validate extended key usage information in certificates will need to define a
182custom "purpose" (see below) or supply a nondefault verification callback
183(L<X509_STORE_set_verify_cb_func(3)>).
184
185X509_STORE_CTX_set_purpose() sets the purpose for the target certificate being
186verified in the I<ctx>. Built-in available values for the I<purpose> argument
187are B<X509_PURPOSE_SSL_CLIENT>, B<X509_PURPOSE_SSL_SERVER>,
188B<X509_PURPOSE_NS_SSL_SERVER>, B<X509_PURPOSE_SMIME_SIGN>,
189B<X509_PURPOSE_SMIME_ENCRYPT>, B<X509_PURPOSE_CRL_SIGN>, B<X509_PURPOSE_ANY>,
190B<X509_PURPOSE_OCSP_HELPER>, B<X509_PURPOSE_TIMESTAMP_SIGN> and
191B<X509_PURPOSE_CODE_SIGN>.  It is also
192possible to create a custom purpose value. Setting a purpose will ensure that
193the key usage declared within certificates in the chain being verified is
194consistent with that purpose as well as, potentially, other checks. Every
195purpose also has an associated default trust value which will also be set at the
196same time. During verification this trust setting will be verified to check it
197is consistent with the trust set by the system administrator for certificates in
198the chain.
199
200X509_STORE_CTX_set_trust() sets the trust value for the target certificate
201being verified in the I<ctx>. Built-in available values for the I<trust>
202argument are B<X509_TRUST_COMPAT>, B<X509_TRUST_SSL_CLIENT>,
203B<X509_TRUST_SSL_SERVER>, B<X509_TRUST_EMAIL>, B<X509_TRUST_OBJECT_SIGN>,
204B<X509_TRUST_OCSP_SIGN>, B<X509_TRUST_OCSP_REQUEST> and B<X509_TRUST_TSA>. It is
205also possible to create a custom trust value. Since X509_STORE_CTX_set_purpose()
206also sets the trust value it is normally sufficient to only call that function.
207If both are called then X509_STORE_CTX_set_trust() should be called after
208X509_STORE_CTX_set_purpose() since the trust setting of the last call will be
209used.
210
211It should not normally be necessary for end user applications to call
212X509_STORE_CTX_purpose_inherit() directly. Typically applications should call
213X509_STORE_CTX_set_purpose() or X509_STORE_CTX_set_trust() instead. Using this
214function it is possible to set the purpose and trust values for the I<ctx> at
215the same time.
216Both I<ctx> and its internal verification parameter pointer must not be NULL.
217The I<def_purpose> and I<purpose> arguments can have the same
218purpose values as described for X509_STORE_CTX_set_purpose() above. The I<trust>
219argument can have the same trust values as described in
220X509_STORE_CTX_set_trust() above. Any of the I<def_purpose>, I<purpose> or
221I<trust> values may also have the value 0 to indicate that the supplied
222parameter should be ignored. After calling this function the purpose to be used
223for verification is set from the I<purpose> argument unless the purpose was
224already set in I<ctx> before, and the trust is set from the I<trust> argument
225unless the trust was already set in I<ctx> before.
226If I<trust> is 0 then the trust value will be set from
227the default trust value for I<purpose>. If the default trust value for the
228purpose is I<X509_TRUST_DEFAULT> and I<trust> is 0 then the default trust value
229associated with the I<def_purpose> value is used for the trust setting instead.
230
231=head1 NOTES
232
233The certificates and CRLs in a store are used internally and should B<not>
234be freed up until after the associated B<X509_STORE_CTX> is freed.
235
236=head1 BUGS
237
238The certificates and CRLs in a context are used internally and should B<not>
239be freed up until after the associated B<X509_STORE_CTX> is freed. Copies
240should be made or reference counts increased instead.
241
242=head1 RETURN VALUES
243
244X509_STORE_CTX_new() returns a newly allocated context or NULL if an
245error occurred.
246
247X509_STORE_CTX_init() returns 1 for success or 0 if an error occurred.
248
249X509_STORE_CTX_get0_param() returns a pointer to an B<X509_VERIFY_PARAM>
250structure or NULL if an error occurred.
251
252X509_STORE_CTX_cleanup(), X509_STORE_CTX_free(),
253X509_STORE_CTX_set0_trusted_stack(),
254X509_STORE_CTX_set_cert(),
255X509_STORE_CTX_set0_crls() and X509_STORE_CTX_set0_param() do not return
256values.
257
258X509_STORE_CTX_set_default() returns 1 for success or 0 if an error occurred.
259
260X509_STORE_CTX_get_num_untrusted() returns the number of untrusted certificates
261used.
262
263=head1 SEE ALSO
264
265L<X509_verify_cert(3)>, L<X509_STORE_CTX_verify(3)>,
266L<X509_VERIFY_PARAM_set_flags(3)>
267
268=head1 HISTORY
269
270The X509_STORE_CTX_set0_crls() function was added in OpenSSL 1.0.0.
271The X509_STORE_CTX_get_num_untrusted() function was added in OpenSSL 1.1.0.
272The X509_STORE_CTX_new_ex() function was added in OpenSSL 3.0.
273
274There is no need to call X509_STORE_CTX_cleanup() explicitly since OpenSSL 3.0.
275
276=head1 COPYRIGHT
277
278Copyright 2009-2022 The OpenSSL Project Authors. All Rights Reserved.
279
280Licensed under the Apache License 2.0 (the "License").  You may not use
281this file except in compliance with the License.  You can obtain a copy
282in the file LICENSE in the source distribution or at
283L<https://www.openssl.org/source/license.html>.
284
285=cut
286