NAME

SYNOPSIS

 #include <openssl/x509v3.h>

 long X509_get_pathlen(X509 *x);
 uint32_t X509_get_extension_flags(X509 *x);
 uint32_t X509_get_key_usage(X509 *x);
 uint32_t X509_get_extended_key_usage(X509 *x);
 const ASN1_OCTET_STRING *X509_get0_subject_key_id(X509 *x);
 const ASN1_OCTET_STRING *X509_get0_authority_key_id(X509 *x);
 const GENERAL_NAMES *X509_get0_authority_issuer(X509 *x);
 const ASN1_INTEGER *X509_get0_authority_serial(X509 *x);
 void X509_set_proxy_flag(X509 *x);
 void X509_set_proxy_pathlen(int l);
 long X509_get_proxy_pathlen(X509 *x);

DESCRIPTION

X509_get_pathlen() retrieves the path length extension from a certificate. This extension is used to limit the length of a cert chain that may be issued from that CA.

X509_get_extension_flags() retrieves general information about a certificate, it will return one or more of the following flags ored together.

EXFLAG_V1

The certificate is an obsolete version 1 certificate.

EXFLAG_BCONS

The certificate contains a basic constraints extension.

EXFLAG_CA

The certificate contains basic constraints and asserts the CA flag.

EXFLAG_PROXY

The certificate is a valid proxy certificate.

EXFLAG_SI

The certificate is self issued (that is subject and issuer names match).

EXFLAG_SS

The subject and issuer names match and extension values imply it is self signed.

EXFLAG_FRESHEST

The freshest CRL extension is present in the certificate.

EXFLAG_CRITICAL

The certificate contains an unhandled critical extension.

EXFLAG_INVALID

Some certificate extension values are invalid or inconsistent. The certificate should be rejected. This bit may also be raised after an out-of-memory error while processing the X509 object, so it may not be related to the processed ASN1 object itself.

EXFLAG_NO_FINGERPRINT

Failed to compute the internal SHA1 hash value of the certificate. This may be due to malloc failure or because no SHA1 implementation was found.

EXFLAG_INVALID_POLICY

The NID_certificate_policies certificate extension is invalid or inconsistent. The certificate should be rejected. This bit may also be raised after an out-of-memory error while processing the X509 object, so it may not be related to the processed ASN1 object itself.

EXFLAG_KUSAGE

The certificate contains a key usage extension. The value can be retrieved using X509_get_key_usage().

EXFLAG_XKUSAGE

The certificate contains an extended key usage extension. The value can be retrieved using X509_get_extended_key_usage().

X509_get_key_usage() returns the value of the key usage extension. If key usage is present will return zero or more of the flags: KU_DIGITAL_SIGNATURE, KU_NON_REPUDIATION, KU_KEY_ENCIPHERMENT, KU_DATA_ENCIPHERMENT, KU_KEY_AGREEMENT, KU_KEY_CERT_SIGN, KU_CRL_SIGN, KU_ENCIPHER_ONLY or KU_DECIPHER_ONLY corresponding to individual key usage bits. If key usage is absent then UINT32_MAX is returned.

X509_get_extended_key_usage() returns the value of the extended key usage extension. If extended key usage is present it will return zero or more of the flags: XKU_SSL_SERVER, XKU_SSL_CLIENT, XKU_SMIME, XKU_CODE_SIGN XKU_OCSP_SIGN, XKU_TIMESTAMP, XKU_DVCS or XKU_ANYEKU. These correspond to the OIDs id-kp-serverAuth, id-kp-clientAuth, id-kp-emailProtection, id-kp-codeSigning, id-kp-OCSPSigning, id-kp-timeStamping, id-kp-dvcs and anyExtendedKeyUsage respectively. Additionally XKU_SGC is set if either Netscape or Microsoft SGC OIDs are present.

X509_get0_subject_key_id() returns an internal pointer to the subject key identifier of x as an ASN1_OCTET_STRING or NULL if the extension is not present or cannot be parsed.

X509_get0_authority_key_id() returns an internal pointer to the authority key identifier of x as an ASN1_OCTET_STRING or NULL if the extension is not present or cannot be parsed.

X509_get0_authority_issuer() returns an internal pointer to the authority certificate issuer of x as a stack of GENERAL_NAME structures or NULL if the extension is not present or cannot be parsed.

X509_get0_authority_serial() returns an internal pointer to the authority certificate serial number of x as an ASN1_INTEGER or NULL if the extension is not present or cannot be parsed.

X509_set_proxy_flag() marks the certificate with the EXFLAG_PROXY flag. This is for the users who need to mark non-RFC3820 proxy certificates as such, as OpenSSL only detects RFC3820 compliant ones.

X509_set_proxy_pathlen() sets the proxy certificate path length for the given certificate x. This is for the users who need to mark non-RFC3820 proxy certificates as such, as OpenSSL only detects RFC3820 compliant ones.

X509_get_proxy_pathlen() returns the proxy certificate path length for the given certificate x if it is a proxy certificate.

NOTES

If the key usage or extended key usage extension is absent then typically usage is unrestricted. For this reason X509_get_key_usage() and X509_get_extended_key_usage() return UINT32_MAX when the corresponding extension is absent. Applications can additionally check the return value of X509_get_extension_flags() and take appropriate action is an extension is absent.

If X509_get0_subject_key_id() returns NULL then the extension may be absent or malformed. Applications can determine the precise reason using X509_get_ext_d2i().

RETURN VALUES

X509_get_extension_flags(), X509_get_key_usage() and X509_get_extended_key_usage() return sets of flags corresponding to the certificate extension values.

X509_get0_subject_key_id() returns the subject key identifier as a pointer to an ASN1_OCTET_STRING structure or NULL if the extension is absent or an error occurred during parsing.

X509_get_proxy_pathlen() returns the path length value if the given certificate is a proxy one and has a path length set, and -1 otherwise.

SEE ALSO

HISTORY

COPYRIGHT

Licensed under the OpenSSL license (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>.