CT(7ossl)

💅 NAME 💅

okay so bestie, welcome to ct — that's Certificate Transparency, and yes it's giving main character energy in the TLS world ✨

---

🦋 SYNOPSIS 🦋

#include <openssl/ct.h>

---

🌸 DESCRIPTION 🌸

so this library lowkey implements Certificate Transparency (CT) verification for TLS clients, exactly as defined in RFC 6962. no cap. and what that buys you is some confidence that a certificate has actually been publicly logged in a set of CT logs 🫶 like, the certificate is out there in the world where everyone can see it, not sneaking around anonymous. iconic behavior only.

ngl, by default these checks are disabled 💀. you gotta turn them on yourself, using SSL_CTX_enable_ct(3) or SSL_enable_ct(3). that's the whole vibe check — nothing happens until you flip it on.

this library isn't just for verifying either, she's versatile 💅. you can also use it to parse and examine CT data structures, like Signed Certificate Timestamps (SCTs), or to read a list of CT logs. and the functions it gives you are literally 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

obsessed honestly 🎀

---

🔥 SEE ALSO 🔥

• 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) ← not a typo bestie, she's listed twice in the original, and we respect that 🙈
• CT_POLICY_EVAL_CTX_new(3)
• SSL_CTX_set_ct_validation_callback(3)

---

🧚 HISTORY 🧚

the ct library was added in OpenSSL 1.1.0 ⭐ — so she's been around, she's established, she's got history.

---

👑 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>.

fr fr bestie, read the license before you do anything — "except in compliance with the License" means actually comply, mkay? 😭

---

okay that's the whole page, slay 💖 it's OpenSSL 3.5.0, dated 2026-09-25, and that's the CT(7ossl) manual page — periodt 🌈🎀💜