# ct - Certificate Transparency - man(7ssl) - [phpMan]

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

## NAME
       ct - Certificate Transparency

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

## DESCRIPTION
       This library implements Certificate Transparency (CT) verification for TLS clients, as
       defined in RFC 6962. This verification can provide some confidence that a certificate has
       been publicly logged in a set of CT logs.

       By default, these checks are disabled. They can be enabled using [**SSL_CTX_enable_ct**(3)](https://www.chedong.com/phpMan.php/man/SSLCTXenablect/3/markdown) or
       [**SSL_enable_ct**(3)](https://www.chedong.com/phpMan.php/man/SSLenablect/3/markdown).

       This library can also be used to parse and examine CT data structures, such as Signed
       Certificate Timestamps (SCTs), or to read a list of CT logs. There are functions for: -
       decoding and encoding SCTs in DER and TLS wire format.  - printing SCTs.  - verifying the
       authenticity of SCTs.  - loading a CT log list from a CONF file.

## SEE ALSO
       [**d2i_SCT_LIST**(3)](https://www.chedong.com/phpMan.php/man/d2iSCTLIST/3/markdown), [**CTLOG_STORE_new**(3)](https://www.chedong.com/phpMan.php/man/CTLOGSTOREnew/3/markdown), [**CTLOG_STORE_get0_log_by_id**(3)](https://www.chedong.com/phpMan.php/man/CTLOGSTOREget0logbyid/3/markdown), [**SCT_new**(3)](https://www.chedong.com/phpMan.php/man/SCTnew/3/markdown), [**SCT_print**(3)](https://www.chedong.com/phpMan.php/man/SCTprint/3/markdown),
       [**SCT_validate**(3)](https://www.chedong.com/phpMan.php/man/SCTvalidate/3/markdown), [**SCT_validate**(3)](https://www.chedong.com/phpMan.php/man/SCTvalidate/3/markdown), [**CT_POLICY_EVAL_CTX_new**(3)](https://www.chedong.com/phpMan.php/man/CTPOLICYEVALCTXnew/3/markdown),
       [**SSL_CTX_set_ct_validation_callback**(3)](https://www.chedong.com/phpMan.php/man/SSLCTXsetctvalidationcallback/3/markdown)

## HISTORY
       The ct library was added in OpenSSL 1.1.0.

## COPYRIGHT
       Copyright 2016-2017 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>>.

3.0.13                                       2026-07-29                                     [_CT_(7SSL)](https://www.chedong.com/phpMan.php/man/CT/7SSL/markdown)