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NAME

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_enc_flags, EC_KEY_set_enc_flags, EC_KEY_get_conv_form, EC_KEY_set_conv_form, EC_KEY_get_key_method_data, EC_KEY_insert_key_method_data, 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_print, EC_KEY_print_fp — create, destroy and manipulate EC_KEY objects

SYNOPSIS

#include <openssl/ec.h>
#include <openssl/bn.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);

unsigned int
EC_KEY_get_enc_flags(const EC_KEY *key);

void
EC_KEY_set_enc_flags(EC_KEY *key, unsigned int flags);

point_conversion_form_t
EC_KEY_get_conv_form(const EC_KEY *key);

void
EC_KEY_set_conv_form(EC_KEY *key, point_conversion_form_t cform);

void *
EC_KEY_get_key_method_data(EC_KEY *key, void *(*dup_func)(void *), void (*free_func)(void *), void (*clear_free_func)(void *));

void
EC_KEY_insert_key_method_data(EC_KEY *key, void *data, void *(*dup_func)(void *), void (*free_func)(void *), void (*clear_free_func)(void *));

void
EC_KEY_set_asn1_flag(EC_KEY *key, 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);

int
EC_KEY_print(BIO *bp, const EC_KEY *key, int off);

int
EC_KEY_print_fp(FILE *fp, const EC_KEY *key, int off);

DESCRIPTION

An EC_KEY represents a public key and (optionally) an associated private key. The public key is a point on a curve represented by an EC_POINT, see EC_POINT_new(3). The private key is simply a BIGNUM, see BN_new(3).

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. Refer to 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 a NULL pointer, no action occurs.

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

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

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

EC_KEY_generate_key() generates a new public and private key for the supplied key object. key 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 coordinates, 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_enc_flags() and EC_KEY_set_enc_flags() get and set the value of the encoding flags for the 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 key is converted into ASN.1 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.

The format of the external representation of the public key written by i2d_ECPrivateKey(3), such as whether it is stored in a compressed form or not, is described by the point_conversion_form. See EC_GROUP_copy(3) for a description of point_conversion_form.

When reading a private key encoded without an associated public key, for example if EC_PKEY_NO_PUBKEY was used, d2i_ECPrivateKey(3) generates the missing public key automatically. Private keys encoded without parameters, for example if EC_PKEY_NO_PARAMETERS was used, cannot be loaded using d2i_ECPrivateKey(3).

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_form please refer to EC_GROUP_copy(3).

EC_KEY_insert_key_method_data() and EC_KEY_get_key_method_data() enable the caller to associate arbitrary additional data specific to the elliptic curve scheme being used with the EC_KEY object. This data is treated as a "black box" by the EC library. The data to be stored by EC_KEY_insert_key_method_data() is provided in the data parameter, which must have associated functions for duplicating, freeing and "clear_freeing" the data item. If a subsequent EC_KEY_get_key_method_data() call is issued, the functions for duplicating, freeing and "clear_freeing" the data item must be provided again, and they must be the same as they were when the data item was inserted.

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 currently defined standard flags 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 and is defined in <openssl/ecdh.h>. 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_print() and EC_KEY_print_fp() print out the content of key to the BIO bp or to the FILE pointer fp, respectively. Each line is indented by indent spaces.

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.

EC_KEY_copy() returns a pointer to the destination key or NULL on error. In the latter case, part of the content may already have been copied.

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_print(), and EC_KEY_print_fp() 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() and EC_KEY_get0_public_key() return the private or public keys, respectively, associated with the EC_KEY.

EC_KEY_get_enc_flags() returns the value of the current encoding flags for the EC_KEY.

EC_KEY_get_conv_form() returns the point_conversion_form for the EC_KEY.

SEE ALSO

d2i_ECPKParameters(3), EC_GFp_simple_method(3), EC_GROUP_copy(3), EC_GROUP_new(3), EC_KEY_METHOD_new(3), EC_POINT_add(3), EC_POINT_new(3), ECDH_compute_key(3), ECDSA_SIG_new(3), EVP_PKEY_set1_EC_KEY(3)

HISTORY

EC_KEY_new(), 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_enc_flags(), EC_KEY_set_enc_flags(), EC_KEY_get_conv_form(), EC_KEY_set_conv_form(), EC_KEY_get_key_method_data(), EC_KEY_insert_key_method_data(), EC_KEY_set_asn1_flag(), EC_KEY_precompute_mult(), EC_KEY_generate_key(), EC_KEY_check_key(), EC_KEY_print(), and EC_KEY_print_fp() first appeared in OpenSSL 0.9.8 and have been available since OpenBSD 4.5.

EC_KEY_get_flags(), EC_KEY_set_flags(), EC_KEY_clear_flags(), and EC_KEY_set_public_key_affine_coordinates() first appeared in OpenSSL 1.0.1 and have been available since OpenBSD 5.3.