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 - Encapsulates the data required
       to evaluate whether SCTs meet a Certificate Transparency policy

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);

DESCRIPTION

       A CT_POLICY_EVAL_CTX is used by functions that evaluate whether Signed Certificate
       Timestamps (SCTs) fulfil a Certificate Transparency (CT) policy.  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.  This requires:

       • 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.

       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 same thing as CT_POLICY_EVAL_CTX_new_ex() except that it
       uses the default library context and property query string.

       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.

       • 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.

       When no longer required, the CT_POLICY_EVAL_CTX should be passed to
       CT_POLICY_EVAL_CTX_free() to delete it.

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.

RETURN VALUES

       CT_POLICY_EVAL_CTX_new_ex() and CT_POLICY_EVAL_CTX_new() will return NULL if malloc fails.

SEE ALSO

       ct(7)

HISTORY

       CT_POLICY_EVAL_CTX_new_ex was added in OpenSSL 3.0. All other functions were added in
       OpenSSL 1.1.0.

COPYRIGHT

       Copyright 2016-2020 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>.