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. 83This bit may also be raised after an out-of-memory error while 84processing the X509 object, so it may not be related to the processed 85ASN1 object itself. 86 87=item B<EXFLAG_INVALID_POLICY> 88 89The NID_certificate_policies certificate extension is invalid or 90inconsistent. The certificate should be rejected. 91This bit may also be raised after an out-of-memory error while 92processing the X509 object, so it may not be related to the processed 93ASN1 object itself. 94 95=item B<EXFLAG_KUSAGE> 96 97The certificate contains a key usage extension. The value can be retrieved 98using X509_get_key_usage(). 99 100=item B<EXFLAG_XKUSAGE> 101 102The certificate contains an extended key usage extension. The value can be 103retrieved using X509_get_extended_key_usage(). 104 105=back 106 107X509_get_key_usage() returns the value of the key usage extension. If key 108usage is present will return zero or more of the flags: 109B<KU_DIGITAL_SIGNATURE>, B<KU_NON_REPUDIATION>, B<KU_KEY_ENCIPHERMENT>, 110B<KU_DATA_ENCIPHERMENT>, B<KU_KEY_AGREEMENT>, B<KU_KEY_CERT_SIGN>, 111B<KU_CRL_SIGN>, B<KU_ENCIPHER_ONLY> or B<KU_DECIPHER_ONLY> corresponding to 112individual key usage bits. If key usage is absent then B<UINT32_MAX> is 113returned. 114 115X509_get_extended_key_usage() returns the value of the extended key usage 116extension. If extended key usage is present it will return zero or more of the 117flags: B<XKU_SSL_SERVER>, B<XKU_SSL_CLIENT>, B<XKU_SMIME>, B<XKU_CODE_SIGN> 118B<XKU_OCSP_SIGN>, B<XKU_TIMESTAMP>, B<XKU_DVCS> or B<XKU_ANYEKU>. These 119correspond to the OIDs B<id-kp-serverAuth>, B<id-kp-clientAuth>, 120B<id-kp-emailProtection>, B<id-kp-codeSigning>, B<id-kp-OCSPSigning>, 121B<id-kp-timeStamping>, B<id-kp-dvcs> and B<anyExtendedKeyUsage> respectively. 122Additionally B<XKU_SGC> is set if either Netscape or Microsoft SGC OIDs are 123present. 124 125X509_get0_subject_key_id() returns an internal pointer to the subject key 126identifier of B<x> as an B<ASN1_OCTET_STRING> or B<NULL> if the extension 127is not present or cannot be parsed. 128 129X509_get0_authority_key_id() returns an internal pointer to the authority key 130identifier of B<x> as an B<ASN1_OCTET_STRING> or B<NULL> if the extension 131is not present or cannot be parsed. 132 133X509_get0_authority_issuer() returns an internal pointer to the authority 134certificate issuer of B<x> as a stack of B<GENERAL_NAME> structures or 135B<NULL> if the extension is not present or cannot be parsed. 136 137X509_get0_authority_serial() returns an internal pointer to the authority 138certificate serial number of B<x> as an B<ASN1_INTEGER> or B<NULL> if the 139extension is not present or cannot be parsed. 140 141X509_set_proxy_flag() marks the certificate with the B<EXFLAG_PROXY> flag. 142This is for the users who need to mark non-RFC3820 proxy certificates as 143such, as OpenSSL only detects RFC3820 compliant ones. 144 145X509_set_proxy_pathlen() sets the proxy certificate path length for the given 146certificate B<x>. This is for the users who need to mark non-RFC3820 proxy 147certificates as such, as OpenSSL only detects RFC3820 compliant ones. 148 149X509_get_proxy_pathlen() returns the proxy certificate path length for the 150given certificate B<x> if it is a proxy certificate. 151 152=head1 NOTES 153 154The value of the flags correspond to extension values which are cached 155in the B<X509> structure. If the flags returned do not provide sufficient 156information an application should examine extension values directly 157for example using X509_get_ext_d2i(). 158 159If the key usage or extended key usage extension is absent then typically usage 160is unrestricted. For this reason X509_get_key_usage() and 161X509_get_extended_key_usage() return B<UINT32_MAX> when the corresponding 162extension is absent. Applications can additionally check the return value of 163X509_get_extension_flags() and take appropriate action is an extension is 164absent. 165 166If X509_get0_subject_key_id() returns B<NULL> then the extension may be 167absent or malformed. Applications can determine the precise reason using 168X509_get_ext_d2i(). 169 170=head1 RETURN VALUES 171 172X509_get_pathlen() returns the path length value, or -1 if the extension 173is not present. 174 175X509_get_extension_flags(), X509_get_key_usage() and 176X509_get_extended_key_usage() return sets of flags corresponding to the 177certificate extension values. 178 179X509_get0_subject_key_id() returns the subject key identifier as a 180pointer to an B<ASN1_OCTET_STRING> structure or B<NULL> if the extension 181is absent or an error occurred during parsing. 182 183X509_get_proxy_pathlen() returns the path length value if the given 184certificate is a proxy one and has a path length set, and -1 otherwise. 185 186=head1 SEE ALSO 187 188L<X509_check_purpose(3)> 189 190=head1 HISTORY 191 192X509_get_pathlen(), X509_set_proxy_flag(), X509_set_proxy_pathlen() and 193X509_get_proxy_pathlen() were added in OpenSSL 1.1.0. 194 195=head1 COPYRIGHT 196 197Copyright 2015-2020 The OpenSSL Project Authors. All Rights Reserved. 198 199Licensed under the OpenSSL license (the "License"). You may not use 200this file except in compliance with the License. You can obtain a copy 201in the file LICENSE in the source distribution or at 202L<https://www.openssl.org/source/license.html>. 203 204=cut 205