.\" $OpenBSD: BASIC_CONSTRAINTS_new.3,v 1.6 2021/10/27 11:24:47 schwarze Exp $
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.\" Copyright (c) 2016 Ingo Schwarze <schwarze@openbsd.org>
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.Dd $Mdocdate: October 27 2021 $
.Dt BASIC_CONSTRAINTS_NEW 3
.Os
.Sh NAME
.Nm BASIC_CONSTRAINTS_new ,
.Nm BASIC_CONSTRAINTS_free
.Nd X.509 extension to mark CA certificates
.Sh SYNOPSIS
.In openssl/x509v3.h
.Ft BASIC_CONSTRAINTS *
.Fn BASIC_CONSTRAINTS_new void
.Ft void
.Fn BASIC_CONSTRAINTS_free "BASIC_CONSTRAINTS *bc"
.Sh DESCRIPTION
.Fn BASIC_CONSTRAINTS_new
allocates and initializes an empty
.Vt BASIC_CONSTRAINTS
object, representing an ASN.1
.Vt BasicConstraints
structure defined in RFC 5280 section 4.2.1.9.
.Pp
This object contains two fields.
The field
.Fa "int ca"
is non-zero if the certificate is a CA certificate.
The field
.Fa "ASN1_INTEGER *pathlen"
specifies the maximum number of non-self-issued intermediate
certificates that may follow this certificate in a valid
certification path.
.Pp
If an X.509 version 3 certificate does not contain this extension
or if the
.Fa ca
field of the
.Vt BASIC_CONSTRAINTS
object is 0, or if the certificate contains a key usage extension
having the
.Dv KU_KEY_CERT_SIGN
bit unset, then it is not a CA certificate but an end entity
certificate.
.Pp
.Fn BASIC_CONSTRAINTS_free
frees
.Fa bc .
.Sh RETURN VALUES
.Fn BASIC_CONSTRAINTS_new
returns the new
.Vt BASIC_CONSTRAINTS
object or
.Dv NULL
if an error occurs.
.Sh SEE ALSO
.Xr d2i_BASIC_CONSTRAINTS 3 ,
.Xr X509_check_purpose 3 ,
.Xr X509_EXTENSION_new 3 ,
.Xr X509_get_extension_flags 3 ,
.Xr X509_new 3
.Sh STANDARDS
RFC 5280: Internet X.509 Public Key Infrastructure Certificate and
Certificate Revocation List (CRL) Profile:
.Bl -dash -compact
.It
section 4.2.1.9: Basic Constraints
.It
section 6.1: Basic Path Validation
.El
.Sh HISTORY
.Fn BASIC_CONSTRAINTS_new
and
.Fn BASIC_CONSTRAINTS_free
first appeared in OpenSSL 0.9.2b and have been available since
.Ox 2.6 .