CT_POLICY_EVAL_CTX_NEW(3ossl)

💖 CT_POLICY_EVAL_CTX_NEW 💖

okay bestie, welcome to CT_POLICY_EVAL_CTX_NEW(3ossl) — this is the 3ossl manual page and it's literally all about one little struct that holds everything you need to check whether some SCTs actually satisfy a Certificate Transparency policy. 🦋

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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 — it's giving "encapsulates the data required to evaluate whether SCTs meet a Certificate Transparency policy". periodt. 👑

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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 basically, a CT_POLICY_EVAL_CTX is what the functions use when they're checking whether Signed Certificate Timestamps (SCTs) fulfil a Certificate Transparency (CT) policy. the policy could be, for example, that at least one valid SCT is available. to figure that out, an SCT's timestamp and signature both need to be verified. and for that you need:

• 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

all of the above gets handled with the setters below, bestie. no cap. ✨

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.

CT_POLICY_EVAL_CTX_new() does the exact same thing as CT_POLICY_EVAL_CTX_new_ex() except that it uses the default library context and property query string. slay, defaults.

then you populate the CT_POLICY_EVAL_CTX using:

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

Increments the reference count of the certificate.

• CT_POLICY_EVAL_CTX_set1_issuer() to provide the issuer certificate

Increments the reference count of the certificate.

• 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.

• 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.

each setter has a matching getter for accessing the current value — iconic symmetry, honestly. 🫶

when you're done with it, pass the CT_POLICY_EVAL_CTX to CT_POLICY_EVAL_CTX_free() to delete it. and if the argument to CT_POLICY_EVAL_CTX_free() is NULL, nothing is done. very chill of it. 😌

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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. that's gonna 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. 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 return values section, she's short but she's honest.

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🦋 SEE ALSO 🦋

ct(7) — go read it, bestie.

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⭐ HISTORY ⭐

CT_POLICY_EVAL_CTX_new_ex was added in OpenSSL 3.0. all the other functions were added in OpenSSL 1.1.0. glow-up timeline fr fr.

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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>.

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and that's the whole page, babe 💖 this was OpenSSL 3.5.9, dated 2026-09-29, from the CT_POLICY_EVAL_CTX_NEW(3ossl) manual. go forth and evaluate your CT policies, main character. 🌸✨