CT_POLICY_EVAL_CTX_NEW(3ossl)

💖 CT_POLICY_EVAL_CTX_NEW(3ossl) — OpenSSL edition, bestie 💖

Okay so this is the OpenSSL manual page for CT_POLICY_EVAL_CTX_NEW(3ossl), and it's literally the whole vibe for checking whether SCTs meet a Certificate Transparency policy. No cap, it's giving "trust but verify" main character energy. Let's get into it 🫶

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✨ NAME ✨

CT_POLICY_EVAL_CTX_new_ex, CT_POLICY_EVAL_CTX_new, CT_POLICY_EVAL_CTX_free, CT_POLICY_EVAL_CTX_get0_cert, CT_POLICY_EVAL_CTX_set1_cert, CT_POLICY_EVAL_CTX_get0_issuer, CT_POLICY_EVAL_CTX_set1_issuer, CT_POLICY_EVAL_CTX_get0_log_store, CT_POLICY_EVAL_CTX_set_shared_CTLOG_STORE, CT_POLICY_EVAL_CTX_get_time, CT_POLICY_EVAL_CTX_set_time — all of these encapsulate the data required to evaluate whether SCTs meet a Certificate Transparency policy. Slay 💅

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🎀 SYNOPSIS 🎀

#include <openssl/ct.h>

CT_POLICY_EVAL_CTX *CT_POLICY_EVAL_CTX_new_ex(OSSL_LIB_CTX *libctx,
                                              const char *propq);
CT_POLICY_EVAL_CTX *CT_POLICY_EVAL_CTX_new(void);
void CT_POLICY_EVAL_CTX_free(CT_POLICY_EVAL_CTX *ctx);
X509* CT_POLICY_EVAL_CTX_get0_cert(const CT_POLICY_EVAL_CTX *ctx);
int CT_POLICY_EVAL_CTX_set1_cert(CT_POLICY_EVAL_CTX *ctx, X509 *cert);
X509* CT_POLICY_EVAL_CTX_get0_issuer(const CT_POLICY_EVAL_CTX *ctx);
int CT_POLICY_EVAL_CTX_set1_issuer(CT_POLICY_EVAL_CTX *ctx, X509 *issuer);
const CTLOG_STORE *CT_POLICY_EVAL_CTX_get0_log_store(const CT_POLICY_EVAL_CTX *ctx);
void CT_POLICY_EVAL_CTX_set_shared_CTLOG_STORE(CT_POLICY_EVAL_CTX *ctx,
                                               CTLOG_STORE *log_store);
uint64_t CT_POLICY_EVAL_CTX_get_time(const CT_POLICY_EVAL_CTX *ctx);
void CT_POLICY_EVAL_CTX_set_time(CT_POLICY_EVAL_CTX *ctx, uint64_t time_in_ms);

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🌸 DESCRIPTION 🌸

So a CT_POLICY_EVAL_CTX is used by functions that evaluate whether Signed Certificate Timestamps (SCTs) fulfil a Certificate Transparency (CT) policy. Bestie, this policy may be, for example, that at least one valid SCT is available. To determine this, an SCT's timestamp and signature must be verified. It's literally required:

• the public key of the log that issued the SCT 🔑
• the certificate that the SCT was issued for 📜
• the issuer certificate (if the SCT was issued for a pre-certificate) 👑
• the current time ⏰

The above requirements are met using the setters described below. Obsessed with a clean setup, honestly.

CT_POLICY_EVAL_CTX_new_ex() creates an empty policy evaluation context and associates it with the given library context libctx and property query string propq. It's giving "custom environment, custom rules" ✨

CT_POLICY_EVAL_CTX_new() does the same thing as CT_POLICY_EVAL_CTX_new_ex() except that it uses the default library context and property query string. Lowkey the easy button 🎀

The CT_POLICY_EVAL_CTX should then be populated using:

• CT_POLICY_EVAL_CTX_set1_cert() to provide the certificate the SCTs were issued for

Increments the reference count of the certificate. Ref count goes brrr 📈

• CT_POLICY_EVAL_CTX_set1_issuer() to provide the issuer certificate

Increments the reference count of the certificate. Again, ref count goes brrr 📈

• CT_POLICY_EVAL_CTX_set_shared_CTLOG_STORE() to provide a list of logs that are trusted as sources of SCTs

Holds a pointer to the CTLOG_STORE, so the CTLOG_STORE must outlive the CT_POLICY_EVAL_CTX. This is important, bestie — don't let it dangle 🙈

• CT_POLICY_EVAL_CTX_set_time() to set the time SCTs should be compared with to determine if they are valid

The SCT timestamp will be compared to this time to check whether the SCT was issued in the future. RFC6962 states that "TLS clients MUST reject SCTs whose timestamp is in the future". By default, this will be set to 5 minutes in the future (e.g. (time() + 300) * 1000), to allow for clock drift.

The time should be in milliseconds since the Unix Epoch. Time math is so real 😭

Each setter has a matching getter for accessing the current value. Iconic symmetry, periodt.

When no longer required, the CT_POLICY_EVAL_CTX should be passed to CT_POLICY_EVAL_CTX_free() to delete it. If the argument to CT_POLICY_EVAL_CTX_free() is NULL, nothing is done. Very demure, very mindful 🧚

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🦋 NOTES 🦋

The issuer certificate only needs to be provided if at least one of the SCTs was issued for a pre-certificate. This will be the case for SCTs embedded in a certificate (i.e. those in an X.509 extension), but may not be the case for SCTs found in the TLS SCT extension or OCSP response. So like, don't over-provide unless you need to, iykyk 💅

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🌈 RETURN VALUES 🌈

CT_POLICY_EVAL_CTX_new_ex() and CT_POLICY_EVAL_CTX_new() will return NULL if malloc fails. That's the whole mood if memory says no 💀

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⭐ SEE ALSO ⭐

ct(7) — go read that too, bestie 🫶

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👑 HISTORY 👑

CT_POLICY_EVAL_CTX_new_ex was added in OpenSSL 3.0. All other functions were added in OpenSSL 1.1.0. Look at the timeline, it's giving legacy with a glow-up ✨

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🍓 COPYRIGHT 🍓

Copyright 2016-2024 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>. Respect the license, bestie, it's not optional 🙏

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💖✨ That's the whole page, bestie ✨💖 — this cutie was brought to you by OpenSSL 3.5.6, dated 2026-04-07, and yes, CT_POLICY_EVAL_CTX_NEW(3ossl) is literally the moment. Slay, and happy verifying 🎀💅