.\" $OpenBSD: EVP_PKEY_add1_attr.3,v 1.3 2021/10/26 18:50:38 jmc Exp $
.\"
.\" Copyright (c) 2021 Ingo Schwarze <schwarze@openbsd.org>
.\"
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.Dd $Mdocdate: October 26 2021 $
.Dt EVP_PKEY_ADD1_ATTR 3
.Os
.Sh NAME
.Nm EVP_PKEY_add1_attr ,
.Nm EVP_PKEY_add1_attr_by_OBJ ,
.Nm EVP_PKEY_add1_attr_by_NID ,
.Nm EVP_PKEY_add1_attr_by_txt ,
.Nm EVP_PKEY_delete_attr ,
.Nm EVP_PKEY_get_attr ,
.Nm EVP_PKEY_get_attr_count ,
.Nm EVP_PKEY_get_attr_by_OBJ ,
.Nm EVP_PKEY_get_attr_by_NID
.Nd X.501 Attributes of private keys
.Sh SYNOPSIS
.In openssl/x509.h
.Ft int
.Fo EVP_PKEY_add1_attr
.Fa "EVP_PKEY *key"
.Fa "X509_ATTRIBUTE *attr"
.Fc
.Ft int
.Fo EVP_PKEY_add1_attr_by_OBJ
.Fa "EVP_PKEY *key"
.Fa "const ASN1_OBJECT *obj"
.Fa "int type"
.Fa "const unsigned char *data"
.Fa "int len"
.Fc
.Ft int
.Fo EVP_PKEY_add1_attr_by_NID
.Fa "EVP_PKEY *key"
.Fa "int nid"
.Fa "int type"
.Fa "const unsigned char *data"
.Fa "int len"
.Fc
.Ft int
.Fo EVP_PKEY_add1_attr_by_txt
.Fa "EVP_PKEY *key"
.Fa "const char *name"
.Fa "int type"
.Fa "const unsigned char *data"
.Fa "int len"
.Fc
.Ft X509_ATTRIBUTE *
.Fo EVP_PKEY_delete_attr
.Fa "EVP_PKEY *key"
.Fa "int index"
.Fc
.Ft X509_ATTRIBUTE *
.Fo EVP_PKEY_get_attr
.Fa "const EVP_PKEY *key"
.Fa "int index"
.Fc
.Ft int
.Fo EVP_PKEY_get_attr_count
.Fa "const EVP_PKEY *key"
.Fc
.Ft int
.Fo EVP_PKEY_get_attr_by_OBJ
.Fa "const EVP_PKEY *key"
.Fa "const ASN1_OBJECT *obj"
.Fa "int start_after"
.Fc
.Ft int
.Fo EVP_PKEY_get_attr_by_NID
.Fa "const EVP_PKEY *key"
.Fa "int nid"
.Fa "int start_after"
.Fc
.Sh DESCRIPTION
These functions support associating an array of X.501 Attributes
with a private key.
Such attributes can for example be included in PKCS#12 structures.
.Pp
.Fn EVP_PKEY_add1_attr
appends a deep copy of the
.Fa attr
using
.Xr X509at_add1_attr 3 .
.Pp
.Fn EVP_PKEY_add1_attr_by_OBJ ,
.Fn EVP_PKEY_add1_attr_by_NID ,
and
.Fn EVP_PKEY_add1_attr_by_txt
create a new X.501 Attribute object using
.Xr X509_ATTRIBUTE_create_by_OBJ 3 ,
.Xr X509_ATTRIBUTE_create_by_NID 3 ,
or
.Xr X509_ATTRIBUTE_create_by_txt 3 ,
respectively, and append it using
.Xr X509at_add1_attr 3 .
.Pp
.Fn EVP_PKEY_delete_attr
deletes the attribute with the zero-based
.Fa index
using
.Xr X509at_delete_attr 3 .
.Pp
.Fn EVP_PKEY_get_attr
returns the attribute with the zero-based
.Fa index
using
.Xr X509at_get_attr 3 .
.Pp
.Fn EVP_PKEY_get_attr_count
returns the number of attributes currently associated with the
.Fa key
using
.Xr X509at_get_attr_count 3 .
.Pp
.Fn EVP_PKEY_get_attr_by_OBJ
and
.Fn EVP_PKEY_get_attr_by_NID
search for an attribute of the type
.Fa obj
or
.Fa nid
using
.Xr X509at_get_attr_by_OBJ 3
or
.Xr X509at_get_attr_by_NID 3 ,
respectively.
.Sh RETURN VALUES
.Fn EVP_PKEY_add1_attr ,
.Fn EVP_PKEY_add1_attr_by_OBJ ,
.Fn EVP_PKEY_add1_attr_by_NID ,
and
.Fn EVP_PKEY_add1_attr_by_txt
return 1 for success or 0 for failure.
.Pp
.Fn EVP_PKEY_delete_attr
and
.Fn EVP_PKEY_get_attr
return the deleted or requested attribute or
.Dv NULL
if the requested index is negative or greater than or equal to
the current number of attributes associated with the
.Fa key .
.Pp
.Fn EVP_PKEY_get_attr_count
returns the current number of attributes.
.Pp
.Fn EVP_PKEY_get_attr_by_OBJ
and
.Fn EVP_PKEY_get_attr_by_NID
return the index of the first attribute that has an index greater than
.Fa start_after
and a type matching
.Fa obj
or
.Fa nid ,
respectively, or \-1 on failure.
In addition,
.Fn EVP_PKEY_get_attr_by_NID
returns \-2 if
.Xr OBJ_nid2obj 3
fails on the requested
.Fa nid .
.Sh SEE ALSO
.Xr EVP_PKEY_new 3 ,
.Xr OBJ_nid2obj 3 ,
.Xr PKCS12_create 3 ,
.Xr X509_ATTRIBUTE_create_by_OBJ 3 ,
.Xr X509_ATTRIBUTE_new 3 ,
.Xr X509at_add1_attr 3 ,
.Xr X509at_get_attr 3
.Sh HISTORY
These functions first appeared in OpenSSL 0.9.8
and have been available since
.Ox 4.5 .