EC_KEY_oct2key (3)

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NAME

EC_KEY_get_method, EC_KEY_set_method, EC_KEY_new, EC_KEY_get_flags, EC_KEY_set_flags, EC_KEY_clear_flags, EC_KEY_new_by_curve_name, EC_KEY_free, EC_KEY_copy, EC_KEY_dup, EC_KEY_up_ref, EC_KEY_get0_group, EC_KEY_set_group, EC_KEY_get0_private_key, EC_KEY_set_private_key, EC_KEY_get0_public_key, EC_KEY_set_public_key, EC_KEY_get_conv_form, EC_KEY_set_conv_form, EC_KEY_set_asn1_flag, EC_KEY_precompute_mult, EC_KEY_generate_key, EC_KEY_check_key, EC_KEY_set_public_key_affine_coordinates, EC_KEY_oct2key, EC_KEY_key2buf, EC_KEY_oct2priv, EC_KEY_priv2oct, EC_KEY_priv2buf - Functions for creating, destroying and manipulating EC_KEY objects

SYNOPSIS

 #include <openssl/ec.h>

 EC_KEY *EC_KEY_new(void);
 int EC_KEY_get_flags(const EC_KEY *key);
 void EC_KEY_set_flags(EC_KEY *key, int flags);
 void EC_KEY_clear_flags(EC_KEY *key, int flags);
 EC_KEY *EC_KEY_new_by_curve_name(int nid);
 void EC_KEY_free(EC_KEY *key);
 EC_KEY *EC_KEY_copy(EC_KEY *dst, const EC_KEY *src);
 EC_KEY *EC_KEY_dup(const EC_KEY *src);
 int EC_KEY_up_ref(EC_KEY *key);
 const EC_GROUP *EC_KEY_get0_group(const EC_KEY *key);
 int EC_KEY_set_group(EC_KEY *key, const EC_GROUP *group);
 const BIGNUM *EC_KEY_get0_private_key(const EC_KEY *key);
 int EC_KEY_set_private_key(EC_KEY *key, const BIGNUM *prv);
 const EC_POINT *EC_KEY_get0_public_key(const EC_KEY *key);
 int EC_KEY_set_public_key(EC_KEY *key, const EC_POINT *pub);
 point_conversion_form_t EC_KEY_get_conv_form(const EC_KEY *key);
 void EC_KEY_set_conv_form(EC_KEY *eckey, point_conversion_form_t cform);
 void EC_KEY_set_asn1_flag(EC_KEY *eckey, int asn1_flag);
 int EC_KEY_precompute_mult(EC_KEY *key, BN_CTX *ctx);
 int EC_KEY_generate_key(EC_KEY *key);
 int EC_KEY_check_key(const EC_KEY *key);
 int EC_KEY_set_public_key_affine_coordinates(EC_KEY *key,
                                              BIGNUM *x, BIGNUM *y);
 const EC_KEY_METHOD *EC_KEY_get_method(const EC_KEY *key);
 int EC_KEY_set_method(EC_KEY *key, const EC_KEY_METHOD *meth);

 int EC_KEY_oct2key(EC_KEY *eckey, const unsigned char *buf, size_t len,
                    BN_CTX *ctx);
 size_t EC_KEY_key2buf(const EC_KEY *eckey, point_conversion_form_t form,
                       unsigned char **pbuf, BN_CTX *ctx);

 int EC_KEY_oct2priv(EC_KEY *eckey, const unsigned char *buf, size_t len);
 size_t EC_KEY_priv2oct(const EC_KEY *eckey, unsigned char *buf, size_t len);

 size_t EC_KEY_priv2buf(const EC_KEY *eckey, unsigned char **pbuf);

DESCRIPTION

An represents a public key and, optionally, the associated private key. A new with no associated curve can be constructed by calling EC_KEY_new(). The reference count for the newly created is initially set to 1. A curve can be associated with the by calling EC_KEY_set_group().

Alternatively a new

can be constructed by calling EC_KEY_new_by_curve_name() and supplying the nid of the associated curve. See EC_GROUP_new(3) for a description of curve names. This function simply wraps calls to EC_KEY_new() and EC_GROUP_new_by_curve_name().

Calling EC_KEY_free() decrements the reference count for the

object, and if it has dropped to zero then frees the memory associated with it. If key is nothing is done.

EC_KEY_copy() copies the contents of the

in src into dest.

EC_KEY_dup() creates a new

object and copies ec_key into it.

EC_KEY_up_ref() increments the reference count associated with the

object.

EC_KEY_generate_key() generates a new public and private key for the supplied eckey object. eckey must have an

object associated with it before calling this function. The private key is a random integer (0 < priv_key < order, where order is the order of the object). The public key is an on the curve calculated by multiplying the generator for the curve by the private key.

EC_KEY_check_key() performs various sanity checks on the

object to confirm that it is valid.

EC_KEY_set_public_key_affine_coordinates() sets the public key for key based on its affine co-ordinates; i.e., it constructs an

object based on the supplied x and y values and sets the public key to be this It also performs certain sanity checks on the key to confirm that it is valid.

The functions EC_KEY_get0_group(), EC_KEY_set_group(), EC_KEY_get0_private_key(), EC_KEY_set_private_key(), EC_KEY_get0_public_key(), and EC_KEY_set_public_key() get and set the

object, the private key, and the public key for the key respectively.

The functions EC_KEY_get_conv_form() and EC_KEY_set_conv_form() get and set the point_conversion_form for the key. For a description of point_conversion_forms please see EC_POINT_new(3).

EC_KEY_set_flags() sets the flags in the flags parameter on the

object. Any flags that are already set are left set. The flags currently defined are and In addition there is the flag which is specific to EC_KEY_get_flags() returns the current flags that are set for this EC_KEY_clear_flags() clears the flags indicated by the flags parameter; all other flags are left in their existing state.

EC_KEY_set_asn1_flag() sets the asn1_flag on the underlying

object (if set). Refer to EC_GROUP_copy(3) for further information on the asn1_flag.

EC_KEY_precompute_mult() stores multiples of the underlying

generator for faster point multiplication. See also EC_POINT_add(3).

EC_KEY_oct2key() and EC_KEY_key2buf() are identical to the functions EC_POINT_oct2point() and EC_KEY_point2buf() except they use the public key

in eckey.

EC_KEY_oct2priv() and EC_KEY_priv2oct() convert between the private key component of eckey and octet form. The octet form consists of the content octets of the privateKey

in an ECPrivateKey structure.

The function EC_KEY_priv2oct() must be supplied with a buffer long enough to store the octet form. The return value provides the number of octets stored. Calling the function with a

buffer will not perform the conversion but will just return the required buffer length.

The function EC_KEY_priv2buf() allocates a buffer of suitable length and writes an

to it in octet format. The allocated buffer is written to *pbuf and its length is returned. The caller must free up the allocated buffer with a call to OPENSSL_free(). Since the allocated buffer value is written to *pbuf the pbuf parameter be .

EC_KEY_priv2buf() converts an

private key into an allocated buffer.

RETURN VALUES

EC_KEY_new(), EC_KEY_new_by_curve_name() and EC_KEY_dup() return a pointer to the newly created object, or on error.

EC_KEY_get_flags() returns the flags associated with the

object as an integer.

EC_KEY_copy() returns a pointer to the destination key, or

on error.

EC_KEY_up_ref(), EC_KEY_set_group(), EC_KEY_set_private_key(), EC_KEY_set_public_key(), EC_KEY_precompute_mult(), EC_KEY_generate_key(), EC_KEY_check_key(), EC_KEY_set_public_key_affine_coordinates(), EC_KEY_oct2key() and EC_KEY_oct2priv() return 1 on success or 0 on error.

EC_KEY_get0_group() returns the

associated with the

EC_KEY_get0_private_key() returns the private key associated with the

EC_KEY_get_conv_form() return the point_conversion_form for the

EC_KEY_key2buf(), EC_KEY_priv2oct() and EC_KEY_priv2buf() return the length of the buffer or 0 on error.

SEE ALSO

crypto(7), EC_GROUP_new(3), EC_GROUP_copy(3), EC_POINT_new(3), EC_POINT_add(3), EC_GFp_simple_method(3), d2i_ECPKParameters(3)

COPYRIGHT

Copyright 2013-2017 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the OpenSSL license (the ``License''). You may not use this file except in compliance with the License. You can obtain a copy in the file

in the source distribution or at <www.openssl.org/source/license.html>.