xref: /freebsd/crypto/openssl/doc/man3/X509_get_extension_flags.pod (revision f5ef5f675d9d9eb6e35ed9142d70ecf774456ad4)
1=pod
2
3=head1 NAME
4
5X509_get0_subject_key_id,
6X509_get0_authority_key_id,
7X509_get0_authority_issuer,
8X509_get0_authority_serial,
9X509_get_pathlen,
10X509_get_extension_flags,
11X509_get_key_usage,
12X509_get_extended_key_usage,
13X509_set_proxy_flag,
14X509_set_proxy_pathlen,
15X509_get_proxy_pathlen - retrieve certificate extension data
16
17=head1 SYNOPSIS
18
19 #include <openssl/x509v3.h>
20
21 long X509_get_pathlen(X509 *x);
22 uint32_t X509_get_extension_flags(X509 *x);
23 uint32_t X509_get_key_usage(X509 *x);
24 uint32_t X509_get_extended_key_usage(X509 *x);
25 const ASN1_OCTET_STRING *X509_get0_subject_key_id(X509 *x);
26 const ASN1_OCTET_STRING *X509_get0_authority_key_id(X509 *x);
27 const GENERAL_NAMES *X509_get0_authority_issuer(X509 *x);
28 const ASN1_INTEGER *X509_get0_authority_serial(X509 *x);
29 void X509_set_proxy_flag(X509 *x);
30 void X509_set_proxy_pathlen(int l);
31 long X509_get_proxy_pathlen(X509 *x);
32
33=head1 DESCRIPTION
34
35These functions retrieve information related to commonly used certificate extensions.
36
37X509_get_pathlen() retrieves the path length extension from a certificate.
38This extension is used to limit the length of a cert chain that may be
39issued from that CA.
40
41X509_get_extension_flags() retrieves general information about a certificate,
42it will return one or more of the following flags ored together.
43
44=over 4
45
46=item B<EXFLAG_V1>
47
48The certificate is an obsolete version 1 certificate.
49
50=item B<EXFLAG_BCONS>
51
52The certificate contains a basic constraints extension.
53
54=item B<EXFLAG_CA>
55
56The certificate contains basic constraints and asserts the CA flag.
57
58=item B<EXFLAG_PROXY>
59
60The certificate is a valid proxy certificate.
61
62=item B<EXFLAG_SI>
63
64The certificate is self issued (that is subject and issuer names match).
65
66=item B<EXFLAG_SS>
67
68The subject and issuer names match and extension values imply it is self
69signed.
70
71=item B<EXFLAG_FRESHEST>
72
73The freshest CRL extension is present in the certificate.
74
75=item B<EXFLAG_CRITICAL>
76
77The certificate contains an unhandled critical extension.
78
79=item B<EXFLAG_INVALID>
80
81Some certificate extension values are invalid or inconsistent. The
82certificate should be rejected.
83
84=item B<EXFLAG_KUSAGE>
85
86The certificate contains a key usage extension. The value can be retrieved
87using X509_get_key_usage().
88
89=item B<EXFLAG_XKUSAGE>
90
91The certificate contains an extended key usage extension. The value can be
92retrieved using X509_get_extended_key_usage().
93
94=back
95
96X509_get_key_usage() returns the value of the key usage extension.  If key
97usage is present will return zero or more of the flags:
98B<KU_DIGITAL_SIGNATURE>, B<KU_NON_REPUDIATION>, B<KU_KEY_ENCIPHERMENT>,
99B<KU_DATA_ENCIPHERMENT>, B<KU_KEY_AGREEMENT>, B<KU_KEY_CERT_SIGN>,
100B<KU_CRL_SIGN>, B<KU_ENCIPHER_ONLY> or B<KU_DECIPHER_ONLY> corresponding to
101individual key usage bits. If key usage is absent then B<UINT32_MAX> is
102returned.
103
104X509_get_extended_key_usage() returns the value of the extended key usage
105extension. If extended key usage is present it will return zero or more of the
106flags: B<XKU_SSL_SERVER>, B<XKU_SSL_CLIENT>, B<XKU_SMIME>, B<XKU_CODE_SIGN>
107B<XKU_OCSP_SIGN>, B<XKU_TIMESTAMP>, B<XKU_DVCS> or B<XKU_ANYEKU>. These
108correspond to the OIDs B<id-kp-serverAuth>, B<id-kp-clientAuth>,
109B<id-kp-emailProtection>, B<id-kp-codeSigning>, B<id-kp-OCSPSigning>,
110B<id-kp-timeStamping>, B<id-kp-dvcs> and B<anyExtendedKeyUsage> respectively.
111Additionally B<XKU_SGC> is set if either Netscape or Microsoft SGC OIDs are
112present.
113
114X509_get0_subject_key_id() returns an internal pointer to the subject key
115identifier of B<x> as an B<ASN1_OCTET_STRING> or B<NULL> if the extension
116is not present or cannot be parsed.
117
118X509_get0_authority_key_id() returns an internal pointer to the authority key
119identifier of B<x> as an B<ASN1_OCTET_STRING> or B<NULL> if the extension
120is not present or cannot be parsed.
121
122X509_get0_authority_issuer() returns an internal pointer to the authority
123certificate issuer of B<x> as a stack of B<GENERAL_NAME> structures or
124B<NULL> if the extension is not present or cannot be parsed.
125
126X509_get0_authority_serial() returns an internal pointer to the authority
127certificate serial number of B<x> as an B<ASN1_INTEGER> or B<NULL> if the
128extension is not present or cannot be parsed.
129
130X509_set_proxy_flag() marks the certificate with the B<EXFLAG_PROXY> flag.
131This is for the users who need to mark non-RFC3820 proxy certificates as
132such, as OpenSSL only detects RFC3820 compliant ones.
133
134X509_set_proxy_pathlen() sets the proxy certificate path length for the given
135certificate B<x>.  This is for the users who need to mark non-RFC3820 proxy
136certificates as such, as OpenSSL only detects RFC3820 compliant ones.
137
138X509_get_proxy_pathlen() returns the proxy certificate path length for the
139given certificate B<x> if it is a proxy certificate.
140
141=head1 NOTES
142
143The value of the flags correspond to extension values which are cached
144in the B<X509> structure. If the flags returned do not provide sufficient
145information an application should examine extension values directly
146for example using X509_get_ext_d2i().
147
148If the key usage or extended key usage extension is absent then typically usage
149is unrestricted. For this reason X509_get_key_usage() and
150X509_get_extended_key_usage() return B<UINT32_MAX> when the corresponding
151extension is absent. Applications can additionally check the return value of
152X509_get_extension_flags() and take appropriate action is an extension is
153absent.
154
155If X509_get0_subject_key_id() returns B<NULL> then the extension may be
156absent or malformed. Applications can determine the precise reason using
157X509_get_ext_d2i().
158
159=head1 RETURN VALUES
160
161X509_get_pathlen() returns the path length value, or -1 if the extension
162is not present.
163
164X509_get_extension_flags(), X509_get_key_usage() and
165X509_get_extended_key_usage() return sets of flags corresponding to the
166certificate extension values.
167
168X509_get0_subject_key_id() returns the subject key identifier as a
169pointer to an B<ASN1_OCTET_STRING> structure or B<NULL> if the extension
170is absent or an error occurred during parsing.
171
172X509_get_proxy_pathlen() returns the path length value if the given
173certificate is a proxy one and has a path length set, and -1 otherwise.
174
175=head1 SEE ALSO
176
177L<X509_check_purpose(3)>
178
179=head1 HISTORY
180
181X509_get_pathlen(), X509_set_proxy_flag(), X509_set_proxy_pathlen() and
182X509_get_proxy_pathlen() were added in OpenSSL 1.1.0.
183
184=head1 COPYRIGHT
185
186Copyright 2015-2019 The OpenSSL Project Authors. All Rights Reserved.
187
188Licensed under the OpenSSL license (the "License").  You may not use
189this file except in compliance with the License.  You can obtain a copy
190in the file LICENSE in the source distribution or at
191L<https://www.openssl.org/source/license.html>.
192
193=cut
194