# X509(7SSL) - man - phpMan

[X509(7SSL)](https://www.chedong.com/phpMan.php/man/X509/7SSL/markdown)                                     OpenSSL                                    [X509(7SSL)](https://www.chedong.com/phpMan.php/man/X509/7SSL/markdown)



## NAME
       x509 - X.509 certificate handling

## SYNOPSIS
        #include <openssl/x509.h>

## DESCRIPTION
       An X.509 certificate is a structured grouping of information about an individual, a device,
       or anything one can imagine.  An X.509 CRL (certificate revocation list) is a tool to help
       determine if a certificate is still valid.  The exact definition of those can be found in the
       X.509 document from ITU-T, or in RFC3280 from PKIX.  In OpenSSL, the type X509 is used to
       express such a certificate, and the type X509_CRL is used to express a CRL.

       A related structure is a certificate request, defined in PKCS#10 from RSA Security, Inc, also
       reflected in RFC2896.  In OpenSSL, the type X509_REQ is used to express such a certificate
       request.

       To handle some complex parts of a certificate, there are the types X509_NAME (to express a
       certificate name), X509_ATTRIBUTE (to express a certificate attribute), X509_EXTENSION (to
       express a certificate extension) and a few more.

       Finally, there's the supertype X509_INFO, which can contain a CRL, a certificate and a
       corresponding private key.

       **X509**__XXX_, **d2i**___**X509**__XXX_, and **i2d**___**X509**__XXX_ functions handle X.509 certificates, with some
       exceptions, shown below.

       **X509**___**CRL**__XXX_, **d2i**___**X509**___**CRL**__XXX_, and **i2d**___**X509**___**CRL**__XXX_ functions handle X.509 CRLs.

       **X509**___**REQ**__XXX_, **d2i**___**X509**___**REQ**__XXX_, and **i2d**___**X509**___**REQ**__XXX_ functions handle PKCS#10 certificate
       requests.

       **X509**___**NAME**__XXX_ functions handle certificate names.

       **X509**___**ATTRIBUTE**__XXX_ functions handle certificate attributes.

       **X509**___**EXTENSION**__XXX_ functions handle certificate extensions.

## SEE ALSO
       **X509**___**NAME**___**ENTRY**___**get**___**[object**(3)](https://www.chedong.com/phpMan.php/man/object/3/markdown), **X509**___**NAME**___**add**___**entry**___**by**___**[txt**(3)](https://www.chedong.com/phpMan.php/man/txt/3/markdown), **X509**___**NAME**___**add**___**entry**___**by**___**[NID**(3)](https://www.chedong.com/phpMan.php/man/NID/3/markdown),
       **X509**___**NAME**___**print**___**[ex**(3)](https://www.chedong.com/phpMan.php/man/ex/3/markdown), **X509**___**NAME**___**[new**(3)](https://www.chedong.com/phpMan.php/man/new/3/markdown), **PEM**___**X509**___**INFO**___**[read**(3)](https://www.chedong.com/phpMan.php/man/read/3/markdown), **d2i**___**[X509**(3)](https://www.chedong.com/phpMan.php/man/X509/3/markdown),
       **d2i**___**X509**___**[ALGOR**(3)](https://www.chedong.com/phpMan.php/man/ALGOR/3/markdown), **d2i**___**X509**___**[CRL**(3)](https://www.chedong.com/phpMan.php/man/CRL/3/markdown), **d2i**___**X509**___**[NAME**(3)](https://www.chedong.com/phpMan.php/man/NAME/3/markdown), **d2i**___**X509**___**[REQ**(3)](https://www.chedong.com/phpMan.php/man/REQ/3/markdown), **d2i**___**X509**___**[SIG**(3)](https://www.chedong.com/phpMan.php/man/SIG/3/markdown),
       [**crypto**(7)](https://www.chedong.com/phpMan.php/man/crypto/7/markdown)

## COPYRIGHT
       Copyright 2003-2021 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (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>>.



3.0.2                                        2026-04-07                                   [X509(7SSL)](https://www.chedong.com/phpMan.php/man/X509/7SSL/markdown)