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