openssl1.0/doc/crypto/d2i_ECPrivateKey.pod
2019-08-09 10:00:55 +02:00

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=pod
=head1 NAME
i2d_ECPrivateKey, d2i_ECPrivate_key - Encode and decode functions for saving and
reading EC_KEY structures
=head1 SYNOPSIS
#include <openssl/ec.h>
EC_KEY *d2i_ECPrivateKey(EC_KEY **key, const unsigned char **in, long len);
int i2d_ECPrivateKey(EC_KEY *key, unsigned char **out);
unsigned int EC_KEY_get_enc_flags(const EC_KEY *key);
void EC_KEY_set_enc_flags(EC_KEY *eckey, unsigned int flags);
=head1 DESCRIPTION
The ECPrivateKey encode and decode routines encode and parse an
B<EC_KEY> structure into a binary format (ASN.1 DER) and back again.
These functions are similar to the d2i_X509() functions, and you should refer to
that page for a detailed description (see L<d2i_X509(3)|d2i_X509(3)>).
The format of the external representation of the public key written by
i2d_ECPrivateKey (such as whether it is stored in a compressed form or not) is
described by the point_conversion_form. See L<EC_GROUP_copy(3)|EC_GROUP_copy(3)>
for a description of point_conversion_form.
When reading a private key encoded without an associated public key (e.g. if
EC_PKEY_NO_PUBKEY has been used - see below), then d2i_ECPrivateKey generates
the missing public key automatically. Private keys encoded without parameters
(e.g. if EC_PKEY_NO_PARAMETERS has been used - see below) cannot be loaded using
d2i_ECPrivateKey.
The functions EC_KEY_get_enc_flags and EC_KEY_set_enc_flags get and set the
value of the encoding flags for the B<key>. There are two encoding flags
currently defined - EC_PKEY_NO_PARAMETERS and EC_PKEY_NO_PUBKEY. These flags
define the behaviour of how the B<key> is converted into ASN1 in a call to
i2d_ECPrivateKey. If EC_PKEY_NO_PARAMETERS is set then the public parameters for
the curve are not encoded along with the private key. If EC_PKEY_NO_PUBKEY is
set then the public key is not encoded along with the private key.
=head1 RETURN VALUES
d2i_ECPrivateKey() returns a valid B<EC_KEY> structure or B<NULL> if an error
occurs. The error code that can be obtained by
L<ERR_get_error(3)|ERR_get_error(3)>.
i2d_ECPrivateKey() returns the number of bytes successfully encoded or a
negative value if an error occurs. The error code can be obtained by
L<ERR_get_error(3)|ERR_get_error(3)>.
EC_KEY_get_enc_flags returns the value of the current encoding flags for the
EC_KEY.
=head1 SEE ALSO
L<crypto(3)|crypto(3)>, L<ec(3)|ec(3)>, L<EC_GROUP_new(3)|EC_GROUP_new(3)>,
L<EC_GROUP_copy(3)|EC_GROUP_copy(3)>, L<EC_POINT_new(3)|EC_POINT_new(3)>,
L<EC_POINT_add(3)|EC_POINT_add(3)>,
L<EC_GFp_simple_method(3)|EC_GFp_simple_method(3)>,
L<d2i_ECPKParameters(3)|d2i_ECPKParameters(3)>,
L<d2i_ECPrivateKey(3)|d2i_ECPrivateKey(3)>
=cut