=pod

=head1 NAME

X509_check_certificate_times, X509_time_adj, X509_time_adj_ex, X509_gmtime_adj,
X509_cmp_time, X509_cmp_current_time, X509_cmp_timeframe - X509 time functions

=head1 SYNOPSIS

 int X509_check_certificate_times(const X509_VERIFY_PARAM *vpm, const X509 *x,
                                  int *error);
 ASN1_TIME *X509_time_adj(ASN1_TIME *asn1_time, long offset_sec,
                          const time_t *in_tm);
 ASN1_TIME *X509_time_adj_ex(ASN1_TIME *asn1_time, int offset_day, long
                             offset_sec, const time_t *in_tm);
 ASN1_TIME *X509_gmtime_adj(ASN1_TIME *asn1_time, long offset_sec);

The following functions have been deprecated since OpenSSL 4.0, and can be
hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value,
see L<openssl_user_macros(7)>:

 int X509_cmp_time(const ASN1_TIME *asn1_time, const time_t *in_tm);
 int X509_cmp_current_time(const ASN1_TIME *asn1_time);
 int X509_cmp_timeframe(const X509_VERIFY_PARAM *vpm,
                        const ASN1_TIME *start, const ASN1_TIME *end);

=head1 DESCRIPTION

X509_check_certificate_times() compares the notBefore and notAfter
times in certificate I<x> to check the certificate for temporal validity.
The time used for the check will be the current system time, unless
The the reference time included in the verification parameter I<vpm>
is non NULL and I<vpm> has the flag B<X509_V_FLAG_USE_CHECK_TIME> set.

The notBefore and notAfter times in the certificate will be accepted
only if they are either the format of a GeneralizedTime
(YYYYMMDDHHMMSSZ), or a UTCTime (YYMMDDHHMMSSZ) as per RFC5280, with
the exception that the requirement: "CAs conforming to this profile
MUST always encode certificate validity dates through the year 2049 as
UTCTime; certificate validity dates in 2050 or later MUST be encoded
as GeneralizedTime." is not enforced.

X509_cmp_time() compares the ASN1_TIME in I<asn1_time> with the time
in <in_tm>.

X509_cmp_current_time() compares the ASN1_TIME in
I<asn1_time> with the current time, expressed as time_t.

X509_cmp_timeframe() compares the given time period with the reference time
included in the verification parameters I<vpm> if they are not NULL and contain
B<X509_V_FLAG_USE_CHECK_TIME>; else the current time is used as reference time.

X509_time_adj_ex() sets the ASN1_TIME structure I<asn1_time> to the time
I<offset_day> and I<offset_sec> after I<in_tm>.

X509_time_adj() sets the ASN1_TIME structure I<asn1_time> to the time
I<offset_sec> after I<in_tm>. This method can only handle second
offsets up to the capacity of long, so the newer X509_time_adj_ex()
API should be preferred.

In both methods, if I<asn1_time> is NULL, a new ASN1_TIME structure
is allocated and returned.

In all methods, if I<in_tm> is NULL, the current time, expressed as
time_t, is used.

I<asn1_time> must satisfy the ASN1_TIME format mandated by RFC 5280,
i.e., its format must be either YYMMDDHHMMSSZ or YYYYMMDDHHMMSSZ.

X509_gmtime_adj() sets the ASN1_TIME structure I<asn1_time> to the time
I<offset_sec> after the current time. It is equivalent to calling
X509_time_adj() with the last parameter as NULL.

=head1 BUGS

Unlike many standard comparison functions, The deprecated functions
X509_cmp_time() and X509_cmp_current_time() return 0 on error, and
return -1 when the values are equal.

The deprecated function X509_cmp_timeframe() may accept invalid
certificate times as infinitely valid.

=head1 RETURN VALUES

X509_check_certiticate_times() returns 1 if the certificate is
temporally valid at the verification time as per the rules from RFC
5280. It returns 0 otherwise. if I<error> is non NULL, the integer
value it points to will be set to an error code when the certificate
is not temporally valid, or 0 when the certificate is temporally valid.

The integer pointed to by I<error> will be set to
X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD
or
X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD
if the certificate has an invalid notBefore or notAfter field, respectively.

The integer pointed to by I<error> will be set to
X509_V_ERR_CERT_NOT_YET_VALID
or
X509_V_ERR_CERT_HAS_EXPIRED
if the
verification time is outside of the certificate's correctly encoded
validity window as per RFC5280.

X509_cmp_time() and X509_cmp_current_time() return -1 if I<asn1_time>
is earlier than, or equal to, I<in_tm> (resp. current time), and 1
otherwise. These methods return 0 on error.

X509_cmp_timeframe() compares a reference time to a start and end
ASN1_TIME value range. The reference time is compared to the start
value of the range inclusively, and to the end value of the range
exclusively. The reference time used will retrieved from I<vpm> if the
flag I<509_V_FLAG_USE_CHECK_TIME> is set in I<vpm>, otherwise it will
be the current time. The start time used will be I<start> if it is non
NULL, and a valid ASN1_TIME value, otherwise it will be infinitely in
the past. The end time used will be I<end> if it is non NULL and a
valid ASN1_TIME value, otherwise it will be infinitely in the
future. 0 is returned unconditionally if the flag
I<X509_V_FLAG_NO_CHECK_TIME> is set in I<vpm>. Otherwise 0 will be
returned if the reference time is in the range of the start time and
end time as described above. 1 is returned to indicate the reference
time is after or equal to the end time. -1 is returned to indicate the
reference time is before the start time. As this function treats
invalid ASN1_TIME inputs as unlimited times, it should not be used to
for temporal verification of certificates using untrusted inputs that
have not been pre-validated to be correct ASN1_TIME values for a
certificate as per RFC 5280, as invalid values will be accepted
as valid forever.

X509_time_adj(), X509_time_adj_ex() and X509_gmtime_adj() return a pointer to
the updated ASN1_TIME structure, and NULL on error.

=head1 SEE ALSO

L<ASN1_GENERALIZEDTIME_check(3)>
L<ASN1_UTCTIME_check(3)>
L<ASN1_TIME_to_tm(3)>
L<OPENSSL_tm_to_posix(3)> L<OPENSSL_posix_to_tm(3)>
L<X509_verify_cert_error_string(3)>

=head1 HISTORY

X509_cmp_timeframe(), X509_cmp_current_time(), and
X509_cmp_timeframe() were deprecated in OpenSSL 4.0

For replacement, consider using X509_check_certificate_times() for use
with X509 certificates. For applications checking individual ASN1_TIME
values, consider using ASN1_TIME_to_tm(3) with appropriate validity
checking of the I<ASN1_TIME> value for your application, and subsequent
comparison of either the resulting I<tm> structure, or conversion to
posix seconds via OPENSSL_tm_to_posix(3)

X509_check_certificate_times() was added in OpenSSL 4.0.

=head1 COPYRIGHT

Copyright 2017-2026 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
L<https://www.openssl.org/source/license.html>.

=cut
