.\"	$OpenBSD: d2i_BASIC_CONSTRAINTS.3,v 1.1 2016/12/28 20:36:33 schwarze Exp $
.\"
.\" Copyright (c) 2016 Ingo Schwarze <schwarze@openbsd.org>
.\"
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.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
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.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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.Dd $Mdocdate: December 28 2016 $
.Dt D2I_BASIC_CONSTRAINTS 3
.Os
.Sh NAME
.Nm d2i_BASIC_CONSTRAINTS ,
.Nm i2d_BASIC_CONSTRAINTS ,
.Nm d2i_EXTENDED_KEY_USAGE ,
.Nm i2d_EXTENDED_KEY_USAGE
.Nd decode and encode X.509 key usage purposes
.Sh SYNOPSIS
.In openssl/x509v3.h
.Ft BASIC_CONSTRAINTS *
.Fo d2i_BASIC_CONSTRAINTS
.Fa "BASIC_CONSTRAINTS **val_out"
.Fa "const unsigned char **der_in"
.Fa "long length"
.Fc
.Ft int
.Fo i2d_BASIC_CONSTRAINTS
.Fa "BASIC_CONSTRAINTS *val_in"
.Fa "unsigned char **der_out"
.Fc
.Ft EXTENDED_KEY_USAGE *
.Fo d2i_EXTENDED_KEY_USAGE
.Fa "EXTENDED_KEY_USAGE **val_out"
.Fa "const unsigned char **der_in"
.Fa "long length"
.Fc
.Ft int
.Fo i2d_EXTENDED_KEY_USAGE
.Fa "EXTENDED_KEY_USAGE *val_in"
.Fa "unsigned char **der_out"
.Fc
.Sh DESCRIPTION
These functions decode and encode data structures describing the
intended purposes that the key contained in an X.509 certificate
is to be used for.
For details about the semantics, examples, caveats, and bugs, see
.Xr ASN1_item_d2i 3 .
.Pp
.Fn d2i_BASIC_CONSTRAINTS
and
.Fn i2d_BASIC_CONSTRAINTS
decode and encode an ASN.1
.Vt BasicConstraints
structure defined in RFC 5280 section 4.2.1.9.
.Pp
.Fn d2i_EXTENDED_KEY_USAGE
and
.Fn i2d_EXTENDED_KEY_USAGE
decode and encode an ASN.1
.Vt ExtKeyUsageSyntax
structure defined in RFC 5280 section 4.2.1.12.
.Sh RETURN VALUES
.Fn d2i_BASIC_CONSTRAINTS
and
.Fn d2i_EXTENDED_KEY_USAGE
return a
.Vt BASIC_CONSTRAINTS
or
.Vt EXTENDED_KEY_USAGE
object, respectively, or
.Dv NULL
if an error occurs.
.Pp
.Fn i2d_BASIC_CONSTRAINTS
and
.Fn i2d_EXTENDED_KEY_USAGE
return the number of bytes successfully encoded or a negative value
if an error occurs.
.Sh SEE ALSO
.Xr ASN1_item_d2i 3 ,
.Xr BASIC_CONSTRAINTS_new 3 ,
.Xr EXTENDED_KEY_USAGE_new 3 ,
.Xr X509_EXTENSION_new 3
.Sh STANDARDS
RFC 5280: Internet X.509 Public Key Infrastructure Certificate and
Certificate Revocation List (CRL) Profile