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. 82The certificate 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_NO_FINGERPRINT> 88 89Failed to compute the internal SHA1 hash value of the certificate or CRL. 90This may be due to malloc failure or because no SHA1 implementation was found. 91 92=item B<EXFLAG_INVALID_POLICY> 93 94The NID_certificate_policies certificate extension is invalid or 95inconsistent. The certificate should be rejected. 96This bit may also be raised after an out-of-memory error while 97processing the X509 object, so it may not be related to the processed 98ASN1 object itself. 99 100=item B<EXFLAG_KUSAGE> 101 102The certificate contains a key usage extension. The value can be retrieved 103using X509_get_key_usage(). 104 105=item B<EXFLAG_XKUSAGE> 106 107The certificate contains an extended key usage extension. The value can be 108retrieved using X509_get_extended_key_usage(). 109 110=back 111 112X509_get_key_usage() returns the value of the key usage extension. If key 113usage is present will return zero or more of the flags: 114B<KU_DIGITAL_SIGNATURE>, B<KU_NON_REPUDIATION>, B<KU_KEY_ENCIPHERMENT>, 115B<KU_DATA_ENCIPHERMENT>, B<KU_KEY_AGREEMENT>, B<KU_KEY_CERT_SIGN>, 116B<KU_CRL_SIGN>, B<KU_ENCIPHER_ONLY> or B<KU_DECIPHER_ONLY> corresponding to 117individual key usage bits. If key usage is absent then B<UINT32_MAX> is 118returned. 119 120X509_get_extended_key_usage() returns the value of the extended key usage 121extension. If extended key usage is present it will return zero or more of the 122flags: B<XKU_SSL_SERVER>, B<XKU_SSL_CLIENT>, B<XKU_SMIME>, B<XKU_CODE_SIGN> 123B<XKU_OCSP_SIGN>, B<XKU_TIMESTAMP>, B<XKU_DVCS> or B<XKU_ANYEKU>. These 124correspond to the OIDs B<id-kp-serverAuth>, B<id-kp-clientAuth>, 125B<id-kp-emailProtection>, B<id-kp-codeSigning>, B<id-kp-OCSPSigning>, 126B<id-kp-timeStamping>, B<id-kp-dvcs> and B<anyExtendedKeyUsage> respectively. 127Additionally B<XKU_SGC> is set if either Netscape or Microsoft SGC OIDs are 128present. 129 130X509_get0_subject_key_id() returns an internal pointer to the subject key 131identifier of B<x> as an B<ASN1_OCTET_STRING> or B<NULL> if the extension 132is not present or cannot be parsed. 133 134X509_get0_authority_key_id() returns an internal pointer to the authority key 135identifier of B<x> as an B<ASN1_OCTET_STRING> or B<NULL> if the extension 136is not present or cannot be parsed. 137 138X509_get0_authority_issuer() returns an internal pointer to the authority 139certificate issuer of B<x> as a stack of B<GENERAL_NAME> structures or 140B<NULL> if the extension is not present or cannot be parsed. 141 142X509_get0_authority_serial() returns an internal pointer to the authority 143certificate serial number of B<x> as an B<ASN1_INTEGER> or B<NULL> if the 144extension is not present or cannot be parsed. 145 146X509_set_proxy_flag() marks the certificate with the B<EXFLAG_PROXY> flag. 147This is for the users who need to mark non-RFC3820 proxy certificates as 148such, as OpenSSL only detects RFC3820 compliant ones. 149 150X509_set_proxy_pathlen() sets the proxy certificate path length for the given 151certificate B<x>. This is for the users who need to mark non-RFC3820 proxy 152certificates as such, as OpenSSL only detects RFC3820 compliant ones. 153 154X509_get_proxy_pathlen() returns the proxy certificate path length for the 155given certificate B<x> if it is a proxy certificate. 156 157=head1 NOTES 158 159The value of the flags correspond to extension values which are cached 160in the B<X509> structure. If the flags returned do not provide sufficient 161information an application should examine extension values directly 162for example using X509_get_ext_d2i(). 163 164If the key usage or extended key usage extension is absent then typically usage 165is unrestricted. For this reason X509_get_key_usage() and 166X509_get_extended_key_usage() return B<UINT32_MAX> when the corresponding 167extension is absent. Applications can additionally check the return value of 168X509_get_extension_flags() and take appropriate action is an extension is 169absent. 170 171If X509_get0_subject_key_id() returns B<NULL> then the extension may be 172absent or malformed. Applications can determine the precise reason using 173X509_get_ext_d2i(). 174 175=head1 RETURN VALUES 176 177X509_get_pathlen() returns the path length value, or -1 if the extension 178is not present. 179 180X509_get_extension_flags(), X509_get_key_usage() and 181X509_get_extended_key_usage() return sets of flags corresponding to the 182certificate extension values. 183 184X509_get0_subject_key_id() returns the subject key identifier as a 185pointer to an B<ASN1_OCTET_STRING> structure or B<NULL> if the extension 186is absent or an error occurred during parsing. 187 188X509_get_proxy_pathlen() returns the path length value if the given 189certificate is a proxy one and has a path length set, and -1 otherwise. 190 191=head1 SEE ALSO 192 193L<X509_check_purpose(3)> 194 195=head1 HISTORY 196 197X509_get_pathlen(), X509_set_proxy_flag(), X509_set_proxy_pathlen() and 198X509_get_proxy_pathlen() were added in OpenSSL 1.1.0. 199 200=head1 COPYRIGHT 201 202Copyright 2015-2021 The OpenSSL Project Authors. All Rights Reserved. 203 204Licensed under the Apache License 2.0 (the "License"). You may not use 205this file except in compliance with the License. You can obtain a copy 206in the file LICENSE in the source distribution or at 207L<https://www.openssl.org/source/license.html>. 208 209=cut 210