1=pod 2 3=head1 NAME 4 5X509_get0_subject_key_id, 6X509_get0_authority_key_id, 7X509_get_pathlen, 8X509_get_extension_flags, 9X509_get_key_usage, 10X509_get_extended_key_usage, 11X509_set_proxy_flag, 12X509_set_proxy_pathlen, 13X509_get_proxy_pathlen - retrieve certificate extension data 14 15=head1 SYNOPSIS 16 17 #include <openssl/x509v3.h> 18 19 long X509_get_pathlen(X509 *x); 20 uint32_t X509_get_extension_flags(X509 *x); 21 uint32_t X509_get_key_usage(X509 *x); 22 uint32_t X509_get_extended_key_usage(X509 *x); 23 const ASN1_OCTET_STRING *X509_get0_subject_key_id(X509 *x); 24 const ASN1_OCTET_STRING *X509_get0_authority_key_id(X509 *x); 25 void X509_set_proxy_flag(X509 *x); 26 void X509_set_proxy_pathlen(int l); 27 long X509_get_proxy_pathlen(X509 *x); 28 29=head1 DESCRIPTION 30 31These functions retrieve information related to commonly used certificate extensions. 32 33X509_get_pathlen() retrieves the path length extension from a certificate. 34This extension is used to limit the length of a cert chain that may be 35issued from that CA. 36 37X509_get_extension_flags() retrieves general information about a certificate, 38it will return one or more of the following flags ored together. 39 40=over 4 41 42=item B<EXFLAG_V1> 43 44The certificate is an obsolete version 1 certificate. 45 46=item B<EXFLAG_BCONS> 47 48The certificate contains a basic constraints extension. 49 50=item B<EXFLAG_CA> 51 52The certificate contains basic constraints and asserts the CA flag. 53 54=item B<EXFLAG_PROXY> 55 56The certificate is a valid proxy certificate. 57 58=item B<EXFLAG_SI> 59 60The certificate is self issued (that is subject and issuer names match). 61 62=item B<EXFLAG_SS> 63 64The subject and issuer names match and extension values imply it is self 65signed. 66 67=item B<EXFLAG_FRESHEST> 68 69The freshest CRL extension is present in the certificate. 70 71=item B<EXFLAG_CRITICAL> 72 73The certificate contains an unhandled critical extension. 74 75=item B<EXFLAG_INVALID> 76 77Some certificate extension values are invalid or inconsistent. The 78certificate should be rejected. 79 80=item B<EXFLAG_KUSAGE> 81 82The certificate contains a key usage extension. The value can be retrieved 83using X509_get_key_usage(). 84 85=item B<EXFLAG_XKUSAGE> 86 87The certificate contains an extended key usage extension. The value can be 88retrieved using X509_get_extended_key_usage(). 89 90=back 91 92X509_get_key_usage() returns the value of the key usage extension. If key 93usage is present will return zero or more of the flags: 94B<KU_DIGITAL_SIGNATURE>, B<KU_NON_REPUDIATION>, B<KU_KEY_ENCIPHERMENT>, 95B<KU_DATA_ENCIPHERMENT>, B<KU_KEY_AGREEMENT>, B<KU_KEY_CERT_SIGN>, 96B<KU_CRL_SIGN>, B<KU_ENCIPHER_ONLY> or B<KU_DECIPHER_ONLY> corresponding to 97individual key usage bits. If key usage is absent then B<UINT32_MAX> is 98returned. 99 100X509_get_extended_key_usage() returns the value of the extended key usage 101extension. If extended key usage is present it will return zero or more of the 102flags: B<XKU_SSL_SERVER>, B<XKU_SSL_CLIENT>, B<XKU_SMIME>, B<XKU_CODE_SIGN> 103B<XKU_OCSP_SIGN>, B<XKU_TIMESTAMP>, B<XKU_DVCS> or B<XKU_ANYEKU>. These 104correspond to the OIDs B<id-kp-serverAuth>, B<id-kp-clientAuth>, 105B<id-kp-emailProtection>, B<id-kp-codeSigning>, B<id-kp-OCSPSigning>, 106B<id-kp-timeStamping>, B<id-kp-dvcs> and B<anyExtendedKeyUsage> respectively. 107Additionally B<XKU_SGC> is set if either Netscape or Microsoft SGC OIDs are 108present. 109 110X509_get0_subject_key_id() returns an internal pointer to the subject key 111identifier of B<x> as an B<ASN1_OCTET_STRING> or B<NULL> if the extension 112is not present or cannot be parsed. 113 114X509_get0_authority_key_id() returns an internal pointer to the authority 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_set_proxy_flag() marks the certificate with the B<EXFLAG_PROXY> flag. 119This is for the users who need to mark non-RFC3820 proxy certificates as 120such, as OpenSSL only detects RFC3820 compliant ones. 121 122X509_set_proxy_pathlen() sets the proxy certificate path length for the given 123certificate B<x>. This is for the users who need to mark non-RFC3820 proxy 124certificates as such, as OpenSSL only detects RFC3820 compliant ones. 125 126X509_get_proxy_pathlen() returns the proxy certificate path length for the 127given certificate B<x> if it is a proxy certificate. 128 129=head1 NOTES 130 131The value of the flags correspond to extension values which are cached 132in the B<X509> structure. If the flags returned do not provide sufficient 133information an application should examine extension values directly 134for example using X509_get_ext_d2i(). 135 136If the key usage or extended key usage extension is absent then typically usage 137is unrestricted. For this reason X509_get_key_usage() and 138X509_get_extended_key_usage() return B<UINT32_MAX> when the corresponding 139extension is absent. Applications can additionally check the return value of 140X509_get_extension_flags() and take appropriate action is an extension is 141absent. 142 143If X509_get0_subject_key_id() returns B<NULL> then the extension may be 144absent or malformed. Applications can determine the precise reason using 145X509_get_ext_d2i(). 146 147=head1 RETURN VALUES 148 149X509_get_pathlen() returns the path length value, or -1 if the extension 150is not present. 151 152X509_get_extension_flags(), X509_get_key_usage() and 153X509_get_extended_key_usage() return sets of flags corresponding to the 154certificate extension values. 155 156X509_get0_subject_key_id() returns the subject key identifier as a 157pointer to an B<ASN1_OCTET_STRING> structure or B<NULL> if the extension 158is absent or an error occurred during parsing. 159 160X509_get_proxy_pathlen() returns the path length value if the given 161certificate is a proxy one and has a path length set, and -1 otherwise. 162 163=head1 SEE ALSO 164 165L<X509_check_purpose(3)> 166 167=head1 HISTORY 168 169X509_get_pathlen(), X509_set_proxy_flag(), X509_set_proxy_pathlen() and 170X509_get_proxy_pathlen() were added in OpenSSL 1.1.0. 171 172=head1 COPYRIGHT 173 174Copyright 2015-2018 The OpenSSL Project Authors. All Rights Reserved. 175 176Licensed under the OpenSSL license (the "License"). You may not use 177this file except in compliance with the License. You can obtain a copy 178in the file LICENSE in the source distribution or at 179L<https://www.openssl.org/source/license.html>. 180 181=cut 182