CT(7SSL)

💖 ct — Certificate Transparency 💖

okay bestie, gather round, because today we're talking about CT, aka Certificate Transparency, from the OpenSSL girlies. it's giving "who's watching the watchers" energy and honestly? iconic.

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✨ SYNOPSIS ✨

#include <openssl/ct.h>

like that's it. one include. slay.

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🦋 DESCRIPTION 🦋

so this library implements Certificate Transparency (CT) verification for TLS clients, exactly as defined in RFC 6962. and what does that get you? it gives you some confidence that a certificate has been publicly logged in a set of CT logs. like, receipts. the cert has receipts. 🔥

🚨 real talk though: by default, these checks are disabled. they do NOT come pre-turned-on, bestie. you gotta opt in yourself.

you enable them with SSL_CTX_enable_ct(3) or SSL_enable_ct(3). pick your fave, both ate.

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this library can also be used to parse and examine CT data structures, like Signed Certificate Timestamps (SCTs), or to read a list of CT logs. it's multifunctional. main character energy fr.

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 📄

periodt. that's the whole feature list, no cap.

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👀 SEE ALSO 👀

go read these next, they're the extended universe:

• d2i_SCT_LIST(3)
• CTLOG_STORE_new(3)
• CTLOG_STORE_get0_log_by_id(3)
• SCT_new(3)
• SCT_print(3)
• SCT_validate(3)
• SCT_validate(3)
• CT_POLICY_EVAL_CTX_new(3)
• SSL_CTX_set_ct_validation_callback(3)

ngl SCT_validate(3) showing up twice in this list? not me noticing. it's listed twice. in the original. i am simply reporting this. 💀 (and yes i kept it twice because every detail stays, that's the rule 💅)

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🌸 HISTORY 🌸

the ct library was added in OpenSSL 1.1.0. throwback era. vintage. the way she's been around for a minute 😭

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📜 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 of the License in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>.

like, legally, bestie. read the license. i'm not being cute about this one, it's the actual rules 🙈

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and that's the whole page!! 🫶 this was CT(7SSL) from the OpenSSL manual, version 4.0.3, dated 2026-09-29. drink water, enable your CT checks, and stay transparent ✨🎀💜 bye!!