.\"	$OpenBSD: d2i_PrivateKey.3,v 1.2 2016/12/06 14:54:55 schwarze Exp $
.\"	OpenSSL b97fdb57 Nov 11 09:33:09 2016 +0100
.\"
.\" This file was written by Dr. Stephen Henson <steve@openssl.org>.
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.Dd $Mdocdate: December 6 2016 $
.Dt D2I_PRIVATEKEY 3
.Os
.Sh NAME
.Nm d2i_PrivateKey ,
.Nm d2i_AutoPrivateKey ,
.Nm i2d_PrivateKey ,
.Nm d2i_PrivateKey_bio ,
.Nm d2i_PrivateKey_fp
.Nd decode and encode functions for reading and saving EVP_PKEY structures
.Sh SYNOPSIS
.In openssl/evp.h
.Ft EVP_PKEY *
.Fo d2i_PrivateKey
.Fa "int type"
.Fa "EVP_PKEY **a"
.Fa "const unsigned char **pp"
.Fa "long length"
.Fc
.Ft EVP_PKEY *
.Fo d2i_AutoPrivateKey
.Fa "EVP_PKEY **a"
.Fa "const unsigned char **pp"
.Fa "long length"
.Fc
.Ft int
.Fo i2d_PrivateKey
.Fa "EVP_PKEY *a"
.Fa "unsigned char **pp"
.Fc
.Ft EVP_PKEY *
.Fo d2i_PrivateKey_bio
.Fa "BIO *bp"
.Fa "EVP_PKEY **a"
.Fc
.Ft EVP_PKEY *
.Fo d2i_PrivateKey_fp
.Fa "FILE *fp"
.Fa "EVP_PKEY **a"
.Fc
.Sh DESCRIPTION
.Fn d2i_PrivateKey
decodes a private key using algorithm
.Fa type .
It attempts to use any key specific format or PKCS#8 unencrypted
PrivateKeyInfo format.
The
.Fa type
parameter should be a public key algorithm constant such as
.Dv EVP_PKEY_RSA .
An error occurs if the decoded key does not match
.Fa type .
.Pp
.Fn d2i_AutoPrivateKey
is similar to
.Fn d2i_PrivateKey
except that it attempts to automatically detect the private key format.
.Pp
.Fn i2d_PrivateKey
encodes
.Fa a .
It uses a key specific format or, if none is defined for that key type,
PKCS#8 unencrypted PrivateKeyInfo format.
.Pp
These functions are similar to the
.Xr d2i_X509 3
functions; see
.Xr d2i_X509 3 .
.Pp
All these functions use DER format and unencrypted keys.
Applications wishing to encrypt or decrypt private keys should use other
functions such as
.Xr d2i_PKC8PrivateKey 3
instead.
.Pp
If
.Pf * Fa a
is not NULL when calling
.Fn d2i_PrivateKey
or
.Fn d2i_AutoPrivateKey
(i.e. an existing structure is being reused) and the key format is
PKCS#8, then
.Pf * Fa a
will be freed and replaced on a successful call.
.Sh RETURN VALUES
.Fn d2i_PrivateKey
and
.Fn d2i_AutoPrivateKey
return a valid
.Vt EVP_KEY
structure or
.Dv NULL
if an error occurs.
The error code can be obtained by calling
.Xr ERR_get_error 3 .
.Pp
.Fn i2d_PrivateKey
returns the number of bytes successfully encoded or a negative value if
an error occurs.
The error code can be obtained by calling
.Xr ERR_get_error 3 .
.Sh SEE ALSO
.Xr d2i_PKCS8PrivateKey 3