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.\" ========================================================================
.\"
.IX Title "CT 7"
.TH CT 7 "2023-05-30" "3.0.9" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.SH "NAME"
ct \- Certificate Transparency
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/ct.h>
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This library implements Certificate Transparency (\s-1CT\s0) verification for \s-1TLS\s0
clients, as defined in \s-1RFC 6962.\s0 This verification can provide some confidence
that a certificate has been publicly logged in a set of \s-1CT\s0 logs.
.PP
By default, these checks are disabled. They can be enabled using
\&\fBSSL_CTX_enable_ct\fR\|(3) or \fBSSL_enable_ct\fR\|(3).
.PP
This library can also be used to parse and examine \s-1CT\s0 data structures, such as
Signed Certificate Timestamps (SCTs), or to read a list of \s-1CT\s0 logs. There are
functions for:
\&\- decoding and encoding SCTs in \s-1DER\s0 and \s-1TLS\s0 wire format.
\&\- printing SCTs.
\&\- verifying the authenticity of SCTs.
\&\- loading a \s-1CT\s0 log list from a \s-1CONF\s0 file.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBd2i_SCT_LIST\fR\|(3),
\&\fBCTLOG_STORE_new\fR\|(3),
\&\fBCTLOG_STORE_get0_log_by_id\fR\|(3),
\&\fBSCT_new\fR\|(3),
\&\fBSCT_print\fR\|(3),
\&\fBSCT_validate\fR\|(3),
\&\fBSCT_validate\fR\|(3),
\&\fBCT_POLICY_EVAL_CTX_new\fR\|(3),
\&\fBSSL_CTX_set_ct_validation_callback\fR\|(3)
.SH "HISTORY"
.IX Header "HISTORY"
The ct library was added in OpenSSL 1.1.0.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2016\-2017 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the Apache License 2.0 (the \*(L"License\*(R").  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file \s-1LICENSE\s0 in the source distribution or at
<https://www.openssl.org/source/license.html>.