1.\" $OpenBSD: EXTENDED_KEY_USAGE_new.3,v 1.6 2021/10/27 11:24:47 schwarze Exp $ 2.\" 3.\" Copyright (c) 2016 Ingo Schwarze <schwarze@openbsd.org> 4.\" 5.\" Permission to use, copy, modify, and distribute this software for any 6.\" purpose with or without fee is hereby granted, provided that the above 7.\" copyright notice and this permission notice appear in all copies. 8.\" 9.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16.\" 17.Dd $Mdocdate: October 27 2021 $ 18.Dt EXTENDED_KEY_USAGE_NEW 3 19.Os 20.Sh NAME 21.Nm EXTENDED_KEY_USAGE_new , 22.Nm EXTENDED_KEY_USAGE_free 23.Nd X.509 key usage restrictions 24.Sh SYNOPSIS 25.In openssl/x509v3.h 26.Ft EXTENDED_KEY_USAGE 27.Fn EXTENDED_KEY_USAGE_new void 28.Ft void 29.Fn EXTENDED_KEY_USAGE_free "EXTENDED_KEY_USAGE *eku" 30.Sh DESCRIPTION 31By using the key usage extension, the extended key usage extension, 32or both of them, 33.Vt X509 34end entity certificates may indicate that the key contained in them 35is only intended to be used for the specified purposes. 36If both extensions are present, only uses compatible with both 37extensions are intended. 38.Pp 39.Fn EXTENDED_KEY_USAGE_new 40allocates and initializes an empty 41.Vt EXTENDED_KEY_USAGE 42object, which is a 43.Vt STACK_OF(ASN1_OBJECT) 44and represents an ASN.1 45.Vt ExtKeyUsageSyntax 46structure defined in RFC 5280 section 4.2.1.12. 47It can hold key purpose identifiers. 48.Pp 49.Fn EXTENDED_KEY_USAGE_free 50frees 51.Fa eku . 52.Pp 53The key usage extension uses the ASN.1 BIT STRING data type 54and doesn't require any dedicated object. 55.Sh RETURN VALUES 56.Fn EXTENDED_KEY_USAGE_new 57returns the new 58.Vt EXTENDED_KEY_USAGE 59object or 60.Dv NULL 61if an error occurs. 62.Sh SEE ALSO 63.Xr BASIC_CONSTRAINTS_new 3 , 64.Xr d2i_EXTENDED_KEY_USAGE 3 , 65.Xr POLICYINFO_new 3 , 66.Xr X509_check_purpose 3 , 67.Xr X509_EXTENSION_new 3 , 68.Xr X509_get_extension_flags 3 , 69.Xr X509_new 3 70.Sh STANDARDS 71RFC 5280: Internet X.509 Public Key Infrastructure Certificate and 72Certificate Revocation List (CRL) Profile: 73.Bl -dash -compact 74.It 75section 4.2.1.3: Key Usage 76.It 77section 4.2.1.12: Extended Key Usage 78.El 79.Sh HISTORY 80.Fn EXTENDED_KEY_USAGE_new 81and 82.Fn EXTENDED_KEY_USAGE_free 83first appeared in OpenSSL 0.9.7 and have been available since 84.Ox 3.2 . 85