ct(7ssl)

ct7ssl

Certificate transparency

Usage

 #include <openssl/ct.h>

Overview

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) or SSL_enable_ct(3).

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.

Releases

6 releases since Debian 9 (Stretch); the text changed 5 times.

  1. 9
  2. 10
  3. 11
  4. 12
  5. 13
  6. Arch

History

The ct library was added in OpenSSL 1.1.0.

From openssl 3.6.5-1 in Arch Linux 2026-11-01. Parsed by carta from the page's man source.