path: root/lib/libcrypto/man/ASN1_TIME_set.3

.\" $OpenBSD: ASN1_TIME_set.3,v 1.21 2023/11/16 14:20:49 tb Exp $
.\" full merge up to: OpenSSL 3d0f1cb9 Jul 11 03:01:24 2017 +0800
.\" selective merge up to: OpenSSL 24a535ea Sep 22 13:14:20 2020 +0100
.\"
.\" This file is a derived work.
.\" The changes are covered by the following Copyright and license:
.\"
.\" Copyright (c) 2022 Ingo Schwarze <schwarze@openbsd.org>
.\" Copyright (c) 2022 Bob Beck <beck@openbsd.org>
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.\" The original file was written by Dr. Stephen Henson <steve@openssl.org>
.\" and Todd Short <tshort@akamai.com>.
.\" Copyright (c) 2015, 2017 The OpenSSL Project.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\"
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\"
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in
.\"    the documentation and/or other materials provided with the
.\"    distribution.
.\"
.\" 3. All advertising materials mentioning features or use of this
.\"    software must display the following acknowledgment:
.\"    "This product includes software developed by the OpenSSL Project
.\"    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
.\"
.\" 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
.\"    endorse or promote products derived from this software without
.\"    prior written permission. For written permission, please contact
.\"    openssl-core@openssl.org.
.\"
.\" 5. Products derived from this software may not be called "OpenSSL"
.\"    nor may "OpenSSL" appear in their names without prior written
.\"    permission of the OpenSSL Project.
.\"
.\" 6. Redistributions of any form whatsoever must retain the following
.\"    acknowledgment:
.\"    "This product includes software developed by the OpenSSL Project
.\"    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
.\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
.\" PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
.\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
.\" OF THE POSSIBILITY OF SUCH DAMAGE.
.\"
.Dd $Mdocdate: November 16 2023 $
.Dt ASN1_TIME_SET 3
.Os
.Sh NAME
.Nm ASN1_TIME_set ,
.Nm ASN1_UTCTIME_set ,
.Nm ASN1_GENERALIZEDTIME_set ,
.Nm ASN1_TIME_adj ,
.Nm ASN1_UTCTIME_adj ,
.Nm ASN1_GENERALIZEDTIME_adj ,
.Nm ASN1_TIME_set_string ,
.Nm ASN1_TIME_set_string_X509 ,
.Nm ASN1_UTCTIME_set_string ,
.Nm ASN1_GENERALIZEDTIME_set_string ,
.Nm ASN1_TIME_normalize ,
.Nm ASN1_TIME_check ,
.Nm ASN1_UTCTIME_check ,
.Nm ASN1_GENERALIZEDTIME_check ,
.Nm ASN1_TIME_print ,
.Nm ASN1_UTCTIME_print ,
.Nm ASN1_GENERALIZEDTIME_print ,
.Nm ASN1_TIME_to_tm ,
.Nm ASN1_TIME_diff ,
.Nm ASN1_TIME_cmp_time_t ,
.Nm ASN1_UTCTIME_cmp_time_t ,
.Nm ASN1_TIME_compare ,
.Nm ASN1_TIME_to_generalizedtime ,
.Nm OPENSSL_gmtime ,
.Nm OPENSSL_timegm
.Nd ASN.1 Time functions
.Sh SYNOPSIS
.In openssl/asn1.h
.Ft ASN1_TIME *
.Fo ASN1_TIME_set
.Fa "ASN1_TIME *s"
.Fa "time_t t"
.Fc
.Ft ASN1_UTCTIME *
.Fo ASN1_UTCTIME_set
.Fa "ASN1_UTCTIME *s"
.Fa "time_t t"
.Fc
.Ft ASN1_GENERALIZEDTIME *
.Fo ASN1_GENERALIZEDTIME_set
.Fa "ASN1_GENERALIZEDTIME *s"
.Fa "time_t t"
.Fc
.Ft ASN1_TIME *
.Fo ASN1_TIME_adj
.Fa "ASN1_TIME *s"
.Fa "time_t t"
.Fa "int offset_day"
.Fa "long offset_sec"
.Fc
.Ft ASN1_UTCTIME *
.Fo ASN1_UTCTIME_adj
.Fa "ASN1_UTCTIME *s"
.Fa "time_t t"
.Fa "int offset_day"
.Fa "long offset_sec"
.Fc
.Ft ASN1_GENERALIZEDTIME *
.Fo ASN1_GENERALIZEDTIME_adj
.Fa "ASN1_GENERALIZEDTIME *s"
.Fa "time_t t"
.Fa "int offset_day"
.Fa "long offset_sec"
.Fc
.Ft int
.Fo ASN1_TIME_set_string
.Fa "ASN1_TIME *s"
.Fa "const char *str"
.Fc
.Ft int
.Fo ASN1_TIME_set_string_X509
.Fa "ASN1_TIME *s"
.Fa "const char *str"
.Fc
.Ft int
.Fo ASN1_UTCTIME_set_string
.Fa "ASN1_UTCTIME *s"
.Fa "const char *str"
.Fc
.Ft int
.Fo ASN1_GENERALIZEDTIME_set_string
.Fa "ASN1_GENERALIZEDTIME *s"
.Fa "const char *str"
.Fc
.Ft int
.Fo ASN1_TIME_normalize
.Fa "ASN1_TIME *s"
.Fc
.Ft int
.Fo ASN1_TIME_check
.Fa "const ASN1_TIME *t"
.Fc
.Ft int
.Fo ASN1_UTCTIME_check
.Fa "const ASN1_UTCTIME *t"
.Fc
.Ft int
.Fo ASN1_GENERALIZEDTIME_check
.Fa "const ASN1_GENERALIZEDTIME *t"
.Fc
.Ft int
.Fo ASN1_TIME_print
.Fa "BIO *b"
.Fa "const ASN1_TIME *s"
.Fc
.Ft int
.Fo ASN1_UTCTIME_print
.Fa "BIO *b"
.Fa "const ASN1_UTCTIME *s"
.Fc
.Ft int
.Fo ASN1_GENERALIZEDTIME_print
.Fa "BIO *b"
.Fa "const ASN1_GENERALIZEDTIME *s"
.Fc
.Ft int
.Fo ASN1_TIME_to_tm
.Fa "const ASN1_TIME *s"
.Fa "struct tm *tm"
.Fc
.Ft int
.Fo ASN1_TIME_diff
.Fa "int *pday"
.Fa "int *psec"
.Fa "const ASN1_TIME *from"
.Fa "const ASN1_TIME *to"
.Fc
.Ft int
.Fo ASN1_TIME_cmp_time_t
.Fa "const ASN1_TIME *s"
.Fa "time_t t"
.Fc
.Ft int
.Fo ASN1_UTCTIME_cmp_time_t
.Fa "const ASN1_UTCTIME *s"
.Fa "time_t t"
.Fc
.Ft int
.Fo ASN1_TIME_compare
.Fa "const ASN1_TIME *s"
.Fa "const ASN1_TIME *t"
.Fc
.Ft ASN1_GENERALIZEDTIME *
.Fo ASN1_TIME_to_generalizedtime
.Fa "const ASN1_TIME *t"
.Fa "ASN1_GENERALIZEDTIME **out"
.Fc
.Ft struct tm *
.Fo OPENSSL_gmtime
.Fa "const time_t *time"
.Fa "struct tm *out_tm"
.Fc
.Ft int
.Fo OPENSSL_timegm
.Fa "const struct tm *tm"
.Fa "time_t *out_time"
.Fc
.Sh DESCRIPTION
An
.Vt ASN1_TIME
object is a shallow wrapper around a string containing an ASN.1
.Vt Time
value in the restricted format valid in X.509 certificates.
An
.Vt ASN1_TIME
object is either an
.Vt ASN1_UTCTIME
object containing a string of the format
.Ar YYMMDDHHMMSS Ns Cm Z
which is valid for the years 1950 to 2049, or an
.Vt ASN1_GENERALIZEDTIME
object containing a string of the format
.Ar YYYYMMDDHHMMSS Ns Cm Z
which is valid for the years 0000 to 1949 and 2050 to 9999.
In both cases, the mandatory suffix
.Sq Cm Z
represents the GMT time zone.
LibreSSL by design does not support the full syntax of ASN.1 times.
In particular, it neither supports fractional seconds
nor any other time zone.
.Pp
The functions
.Fn ASN1_TIME_set ,
.Fn ASN1_UTCTIME_set ,
and
.Fn ASN1_GENERALIZEDTIME_set
set the time object
.Fa s
to the time represented by the
.Vt time_t
value
.Fa t .
If
.Fa s
is
.Dv NULL ,
a new time object is allocated and returned.
.Pp
The functions
.Fn ASN1_TIME_adj ,
.Fn ASN1_UTCTIME_adj ,
and
.Fn ASN1_GENERALIZEDTIME_adj
set the time object
.Fa s
to the time represented by the time
.Fa offset_day
and
.Fa offset_sec
after the
.Vt time_t
value
.Fa t .
The values of
.Fa offset_day
or
.Fa offset_sec
can be negative to set a time before
.Fa t .
The
.Fa offset_sec
value can also exceed the number of seconds in a day.
If
.Fa s
is
.Dv NULL ,
a new time object is allocated and returned.
.Pp
.Fn ASN1_TIME_adj
may change the type from
.Vt ASN1_GENERALIZEDTIME
to
.Vt ASN1_UTCTIME
or vice versa depending on the resulting year.
The functions
.Fn ASN1_UTCTIME_adj
and
.Fn ASN1_GENERALIZEDTIME_adj
do not modify the type of the return object.
.Pp
The functions
.Fn ASN1_TIME_set_string ,
.Fn ASN1_TIME_set_string_X509 ,
.Fn ASN1_UTCTIME_set_string ,
and
.Fn ASN1_GENERALIZEDTIME_set_string
set the time object
.Fa s
to the time string
.Fa str ,
which must be in appropriate ASN.1 time format:
YYMMDDHHMMSSZ for
.Vt ASN1_UTCTIME ,
YYYYMMDDHHMMSSZ for
.Vt ASN1_GENERALIZEDTIME ,
or either of the two for
.Vt ASN1_TIME .
The string
.Fa str
is copied into
.Fa s .
If
.Fa s
is
.Dv NULL ,
these functions only perform a format check on
.Fa str .
.Pp
In LibreSSL,
.Fn ASN1_TIME_set_string
and
.Fn ASN1_TIME_set_string_X509
behave identically and always set the time object
to a valid value to use in an X.509 certificate.
.Fn ASN1_GENERALIZEDTIME_set_string
may encode a time string that is not valid in an X.509 certificate.
.Pp
The function
.Fn ASN1_TIME_normalize
converts an
.Vt ASN1_GENERALIZEDTIME
into a time value that can be used in a certificate
by changing it to an
.Vt ASN1_UTCTIME
if possible.
It has no effect on an
.Vt ASN1_UTCTIME .
.Pp
The functions
.Fn ASN1_TIME_check ,
.Fn ASN1_UTCTIME_check ,
and
.Fn ASN1_GENERALIZEDTIME_check
check the syntax of the time string contained in the object
.Fa s .
.Pp
The functions
.Fn ASN1_TIME_print ,
.Fn ASN1_UTCTIME_print ,
and
.Fn ASN1_GENERALIZEDTIME_print
print out the time
.Fa s
to
.Vt BIO
.Fa b
in human readable format.
It will be of the format MMM DD HH:MM:SS YYYY [GMT], for example "Feb 3
00:55:52 2015 GMT".
It does not include a newline.
If the time string has an invalid format,
it prints out "Bad time value" and returns an error.
.Pp
The function
.Fn ASN1_TIME_to_tm
converts the time
.Fa s
to the standard
.Vt tm
structure.
If
.Fa s
is
.Dv NULL ,
then the current time is converted.
The output time is always in the GMT time zone.
The
.Fa tm_sec , tm_min , tm_hour , tm_mday , tm_mon ,
and
.Fa tm_year
fields of the
.Vt tm
structure are set to the proper values,
whereas all other fields are set to 0.
If
.Fa tm
is
.Dv NULL ,
this function performs a format check on
.Fa s
only.
.Pp
The function
.Fn ASN1_TIME_diff
sets
.Pf * Fa pday
and
.Pf * Fa psec
to the time difference between
.Fa from
and
.Fa to .
If
.Fa to
represents a time later than
.Fa from ,
then one or both (depending on the time difference) of
.Pf * Fa pday
and
.Pf * Fa psec
will be positive.
If
.Fa to
represents a time earlier than
.Fa from ,
then one or both of
.Pf * Fa pday
and
.Pf * Fa psec
will be negative.
If
.Fa to
and
.Fa from
represent the same time, then
.Pf * Fa pday
and
.Pf * Fa psec
will both be zero.
If both
.Pf * Fa pday
and
.Pf * Fa psec
are nonzero, they will always have the same sign.
The value of
.Pf * Fa psec
will always be less than the number of seconds in a day.
If
.Fa from
or
.Fa to
is
.Dv NULL ,
the current time is used.
.Pp
The functions
.Fn ASN1_TIME_cmp_time_t ,
.Fn ASN1_UTCTIME_cmp_time_t ,
and
.Fn ASN1_TIME_compare
compare the two times represented by
.Fa s
and
.Fa t .
.Pp
The function
.Fn ASN1_TIME_to_generalizedtime
converts the
.Vt ASN1_TIME
.Fa t
to an
.Vt ASN1_GENERALIZEDTIME ,
regardless of year.
If either
.Fa out
or
.Pf * Fa out
is
.Dv NULL ,
then a new object is allocated and must be freed after use.
.Pp
The
.Vt ASN1_TIME ,
.Vt ASN1_UTCTIME ,
and
.Vt ASN1_GENERALIZEDTIME
objects are represented as
.Vt ASN1_STRING
objects internally and can be freed using
.Xr ASN1_STRING_free 3 .
.Pp
It is recommended that
.Vt ASN1_TIME
functions be used instead of
.Vt ASN1_UTCTIME
or
.Vt ASN1_GENERALIZEDTIME
functions because the
.Vt ASN1_UTCTIME
and
.Vt ASN1_GENERALIZEDTIME
functions act only on that specific time format, while the
.Vt ASN1_TIME
functions operate on either format.
.Pp
.Fn OPENSSL_gmtime
converts a time_t value in
.Fa time
to a struct tm in
.Fa out_tm
and also returns the struct passed in on success.
.Pp
.Fn OPENSSL_timegm
converts a time structure in UTC time in
.Fa tm
to a time_t value in
.Fa out_time .
.Sh RETURN VALUES
.Fn ASN1_TIME_set ,
.Fn ASN1_UTCTIME_set ,
.Fn ASN1_GENERALIZEDTIME_set ,
.Fn ASN1_TIME_adj ,
.Fn ASN1_UTCTIME_adj ,
.Fn ASN1_GENERALIZEDTIME_adj ,
and
.Fn ASN1_TIME_to_generalizedtime
return a pointer to a time object or
.Dv NULL
if an error occurred.
.Pp
.Fn ASN1_TIME_set_string ,
.Fn ASN1_TIME_set_string_X509 ,
.Fn ASN1_UTCTIME_set_string ,
and
.Fn ASN1_GENERALIZEDTIME_set_string
return 1 if the time value is successfully set or 0 otherwise.
.Pp
.Fn ASN1_TIME_normalize
returns 1 on success or 0 on error.
.Pp
.Fn ASN1_TIME_check ,
.Fn ASN1_UTCTIME_check ,
and
.Fn ASN1_GENERALIZEDTIME_check
return 1 if the time string contained in the object is syntactically
correct or 0 otherwise.
.Pp
.Fn ASN1_TIME_print ,
.Fn ASN1_UTCTIME_print ,
and
.Fn ASN1_GENERALIZEDTIME_print
return 1 if the time is successfully printed or 0 if an error
occurred (I/O error or invalid time format).
.Pp
.Fn ASN1_TIME_to_tm
returns 1 if the time is successfully parsed
or 0 if an error occurred, usually due to an invalid time format.
.Pp
.Fn ASN1_TIME_diff
returns 1 for success or 0 for failure.
It can for example fail if a time string passed in has invalid syntax.
.Pp
.Fn ASN1_TIME_cmp_time_t ,
.Fn ASN1_UTCTIME_cmp_time_t ,
and
.Fn ASN1_TIME_compare
return \-1 if
.Fa s
is earlier than
.Fa t ,
0 if both are equal, 1 if
.Fa s
is later than
.Fa t ,
or \-2 on error.
.Pp
.Fn OPENSSL_timegm
returns 1 for success or 0 for failure.
It can fail if the time is not representable in a time_t,
or falls outside the range allowed in RFC 5280 times.
.Pp
.Fn OPENSSL_gmtime
returns
.Fa out_tm
on success or NULL for failure.
It can fail if the time is not representable in a struct tm,
or falls outside the range allowed in RFC 5280 times.
.Sh EXAMPLES
Set a time object to one hour after the current time and print it
out:
.Bd -literal -offset indent
#include <time.h>
#include <openssl/asn1.h>

ASN1_TIME *asn1_time;
time_t t;
BIO *b;

t = time(NULL);
asn1_time = ASN1_TIME_adj(NULL, t, 0, 60 * 60);
b = BIO_new_fp(stdout, BIO_NOCLOSE);
if (asn1_time != NULL) {
	ASN1_TIME_print(b, asn1_time);
	BIO_printf(b, "\en");
} else {
	BIO_printf(b, "Time out of range or un-representable\en");
}
ASN1_STRING_free(asn1_time);
BIO_free(b);
.Ed
.Sh SEE ALSO
.Xr ASN1_TIME_new 3 ,
.Xr ASN1_time_parse 3 ,
.Xr X509_cmp_time 3
.Sh STANDARDS
The usage of the ASN.1
.Vt Time ,
.Vt UTCTime ,
and
.Vt GeneralizedTime
data types in X.509 certificates is specified in
RFC 5280, Internet X.509 Public Key Infrastructure Certificate and
Certificate Revocation List (CRL) Profile,
section 4.1.2.5 (TBS Certificate Validity).
.Sh HISTORY
.Fn ASN1_UTCTIME_check
and
.Fn ASN1_UTCTIME_print
first appeared in SSLeay 0.5.1.
.Fn ASN1_UTCTIME_set
first appeared in SSLeay 0.6.0.
.Fn ASN1_UTCTIME_set_string
first appeared in SSLeay 0.9.0.
All these functions have been available since
.Ox 2.4 .
.Pp
.Fn ASN1_TIME_set ,
.Fn ASN1_GENERALIZEDTIME_set ,
.Fn ASN1_GENERALIZEDTIME_set_string ,
.Fn ASN1_GENERALIZEDTIME_check ,
.Fn ASN1_TIME_print ,
and
.Fn ASN1_GENERALIZEDTIME_print
first appeared in OpenSSL 0.9.2b and have been available since
.Ox 2.6 .
.Pp
.Fn ASN1_UTCTIME_cmp_time_t
first appeared in OpenSSL 0.9.6 and has been available since
.Ox 2.9 .
.Pp
.Fn ASN1_TIME_check
and
.Fn ASN1_TIME_to_generalizedtime
first appeared in OpenSSL 0.9.7 and have been available since
.Ox 3.2 .
.Pp
.Fn ASN1_TIME_adj ,
.Fn ASN1_UTCTIME_adj ,
.Fn ASN1_GENERALIZEDTIME_adj ,
and
.Fn ASN1_TIME_set_string
first appeared in OpenSSL 1.0.0 and have been available since
.Ox 4.9 .
.Pp
.Fn ASN1_TIME_diff
first appeared in OpenSSL 1.0.2 and have been available since
.Ox 7.1 .
.Pp
.Fn ASN1_TIME_set_string_X509 ,
.Fn ASN1_TIME_normalize ,
.Fn ASN1_TIME_to_tm ,
.Fn ASN1_TIME_cmp_time_t ,
and
.Fn ASN1_TIME_compare
first appeared in OpenSSL 1.1.1 and have been available since
.Ox 7.2 .
.Pp
.Fn OPENSSL_gmtime
and
.Fn OPENSSL_timegm
first appeared in BoringSSL and have been available since
.Ox 7.5 .
.Sh CAVEATS
Some applications add offset times directly to a
.Vt time_t
value and pass the results to
.Fn ASN1_TIME_set
(or equivalent).
This can cause problems as the
.Vt time_t
value can overflow on some systems resulting in unexpected results.
New applications should use
.Fn ASN1_TIME_adj
instead and pass the offset value in the
.Fa offset_sec
and
.Fa offset_day
parameters instead of directly manipulating a
.Vt time_t
value.