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_engine, 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);
        ENGINE *EC_KEY_get0_engine(const EC_KEY *eckey);
        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 EC_KEY represents a public key and, optionally, the associated private key. A new
       EC_KEY with no associated curve can be constructed by calling EC_KEY_new(). The reference
       count for the newly created EC_KEY is initially set to 1. A curve can be associated with
       the EC_KEY by calling EC_KEY_set_group().

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

       EC_KEY_copy() copies the contents of the EC_KEY in src into dest.

       EC_KEY_dup() creates a new EC_KEY object and copies ec_key into it.

       EC_KEY_up_ref() increments the reference count associated with the EC_KEY object.

       EC_KEY_get0_engine() returns a handle to the ENGINE that has been set for this EC_KEY
       object.

       EC_KEY_generate_key() generates a new public and private key for the supplied eckey
       object. eckey must have an EC_GROUP 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 EC_GROUP object). The public key is an EC_POINT 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 EC_KEY 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 EC_POINT object based on the supplied x and y values
       and sets the public key to be this EC_POINT. 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 EC_GROUP object, the private key, and the EC_POINT 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 EC_KEY object. Any flags
       that are already set are left set. The flags currently defined are EC_FLAG_NON_FIPS_ALLOW
       and EC_FLAG_FIPS_CHECKED. In addition there is the flag EC_FLAG_COFACTOR_ECDH which is
       specific to ECDH.  EC_KEY_get_flags() returns the current flags that are set for this
       EC_KEY.  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 EC_GROUP 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 EC_GROUP 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 EC_POINT 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 OCTET
       STRING in an ECPrivateKey ASN.1 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 NULL 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 EC_KEY
       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 MUST NOT be NULL.

       EC_KEY_priv2buf() converts an EC_KEY 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 EC_KEY object, or NULL on error.

       EC_KEY_get_flags() returns the flags associated with the EC_KEY object as an integer.

       EC_KEY_copy() returns a pointer to the destination key, or NULL on error.

       EC_KEY_get0_engine() returns a pointer to an ENGINE, or NULL if it wasn't set.

       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 EC_GROUP associated with the EC_KEY.

       EC_KEY_get0_private_key() returns the private key associated with the EC_KEY.

       EC_KEY_get_conv_form() return the point_conversion_form for the EC_KEY.

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