src/include/openssl/ec.h

/* Originally written by Bodo Moeller for the OpenSSL project.
 * ====================================================================
 * Copyright (c) 1998-2005 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    openssl-core@openssl.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * This product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */
/* ====================================================================
 * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
 *
 * Portions of the attached software ("Contribution") are developed by
 * SUN MICROSYSTEMS, INC., and are contributed to the OpenSSL project.
 *
 * The Contribution is licensed pursuant to the OpenSSL open source
 * license provided above.
 *
 * The elliptic curve binary polynomial software is originally written by
 * Sheueling Chang Shantz and Douglas Stebila of Sun Microsystems
 * Laboratories. */

#ifndef OPENSSL_HEADER_EC_H
#define OPENSSL_HEADER_EC_H

#include <openssl/base.h>

#if defined(__cplusplus)
extern "C" {
#endif


/* Low-level operations on elliptic curves. */


/* point_conversion_form_t enumerates forms, as defined in X9.62 (ECDSA), for
 * the encoding of a elliptic curve point (x,y) */
typedef enum {
  /* POINT_CONVERSION_COMPRESSED indicates that the point is encoded as z||x,
   * where the octet z specifies which solution of the quadratic equation y
   * is. */
  POINT_CONVERSION_COMPRESSED = 2,

  /* POINT_CONVERSION_COMPRESSED indicates that the point is encoded as
   * z||x||y, where z is the octet 0x04. */
  POINT_CONVERSION_UNCOMPRESSED = 4,

  /* POINT_CONVERSION_HYBRID indicates that the point is encoded as z||x||y,
   * where z specifies which solution of the quadratic equation y is. This is
   * not supported by the code and has never been observed in use.
   *
   * TODO(agl): remove once node.js no longer references this. */
  POINT_CONVERSION_HYBRID = 6,
} point_conversion_form_t;


/* Elliptic curve groups. */

/* EC_GROUP_new_by_curve_name returns a fresh EC_GROUP object for the elliptic
 * curve specified by |nid|, or NULL on error.
 *
 * The supported NIDs are:
 *   NID_secp224r1,
 *   NID_X9_62_prime256v1,
 *   NID_secp384r1,
 *   NID_secp521r1 */
OPENSSL_EXPORT EC_GROUP *EC_GROUP_new_by_curve_name(int nid);

/* EC_GROUP_free frees |group| and the data that it points to. */
OPENSSL_EXPORT void EC_GROUP_free(EC_GROUP *group);

/* EC_GROUP_dup returns a fresh |EC_GROUP| which is equal to |a| or NULL on
 * error. */
OPENSSL_EXPORT EC_GROUP *EC_GROUP_dup(const EC_GROUP *a);

/* EC_GROUP_cmp returns zero if |a| and |b| are the same group and non-zero
 * otherwise. */
OPENSSL_EXPORT int EC_GROUP_cmp(const EC_GROUP *a, const EC_GROUP *b,
                                BN_CTX *ignored);

/* EC_GROUP_get0_generator returns a pointer to the internal |EC_POINT| object
 * in |group| that specifies the generator for the group. */
OPENSSL_EXPORT const EC_POINT *EC_GROUP_get0_generator(const EC_GROUP *group);

/* EC_GROUP_get0_order returns a pointer to the internal |BIGNUM| object in
 * |group| that specifies the order of the group. */
OPENSSL_EXPORT const BIGNUM *EC_GROUP_get0_order(const EC_GROUP *group);

/* EC_GROUP_get_cofactor sets |*cofactor| to the cofactor of |group| using
 * |ctx|, if it's not NULL. It returns one on success and zero otherwise. */
OPENSSL_EXPORT int EC_GROUP_get_cofactor(const EC_GROUP *group,
                                         BIGNUM *cofactor, BN_CTX *ctx);

/* EC_GROUP_get_curve_GFp gets various parameters about a group. It sets
 * |*out_p| to the order of the coordinate field and |*out_a| and |*out_b| to
 * the parameters of the curve when expressed as y² = x³ + ax + b. Any of the
 * output parameters can be NULL. It returns one on success and zero on
 * error. */
OPENSSL_EXPORT int EC_GROUP_get_curve_GFp(const EC_GROUP *group, BIGNUM *out_p,
                                          BIGNUM *out_a, BIGNUM *out_b,
                                          BN_CTX *ctx);

/* EC_GROUP_get_curve_name returns a NID that identifies |group|. */
OPENSSL_EXPORT int EC_GROUP_get_curve_name(const EC_GROUP *group);

/* EC_GROUP_get_degree returns the number of bits needed to represent an
 * element of the field underlying |group|. */
OPENSSL_EXPORT unsigned EC_GROUP_get_degree(const EC_GROUP *group);


/* Points on elliptic curves. */

/* EC_POINT_new returns a fresh |EC_POINT| object in the given group, or NULL
 * on error. */
OPENSSL_EXPORT EC_POINT *EC_POINT_new(const EC_GROUP *group);

/* EC_POINT_free frees |point| and the data that it points to. */
OPENSSL_EXPORT void EC_POINT_free(EC_POINT *point);

/* EC_POINT_clear_free clears the data that |point| points to, frees it and
 * then frees |point| itself. */
OPENSSL_EXPORT void EC_POINT_clear_free(EC_POINT *point);

/* EC_POINT_copy sets |*dest| equal to |*src|. It returns one on success and
 * zero otherwise. */
OPENSSL_EXPORT int EC_POINT_copy(EC_POINT *dest, const EC_POINT *src);

/* EC_POINT_dup returns a fresh |EC_POINT| that contains the same values as
 * |src|, or NULL on error. */
OPENSSL_EXPORT EC_POINT *EC_POINT_dup(const EC_POINT *src,
                                      const EC_GROUP *group);

/* EC_POINT_set_to_infinity sets |point| to be the "point at infinity" for the
 * given group. */
OPENSSL_EXPORT int EC_POINT_set_to_infinity(const EC_GROUP *group,
                                            EC_POINT *point);

/* EC_POINT_is_at_infinity returns one iff |point| is the point at infinity and
 * zero otherwise. */
OPENSSL_EXPORT int EC_POINT_is_at_infinity(const EC_GROUP *group,
                                           const EC_POINT *point);

/* EC_POINT_is_on_curve returns one if |point| is an element of |group| and
 * and zero otherwise or when an error occurs. This is different from OpenSSL,
 * which returns -1 on error. If |ctx| is non-NULL, it may be used. */
OPENSSL_EXPORT int EC_POINT_is_on_curve(const EC_GROUP *group,
                                        const EC_POINT *point, BN_CTX *ctx);

/* EC_POINT_cmp returns zero if |a| is equal to |b|, greater than zero if
 * not equal and -1 on error. If |ctx| is not NULL, it may be used. */
OPENSSL_EXPORT int EC_POINT_cmp(const EC_GROUP *group, const EC_POINT *a,
                                const EC_POINT *b, BN_CTX *ctx);

/* EC_POINT_make_affine converts |point| to affine form, internally. It returns
 * one on success and zero otherwise. If |ctx| is not NULL, it may be used. */
OPENSSL_EXPORT int EC_POINT_make_affine(const EC_GROUP *group, EC_POINT *point,
                                        BN_CTX *ctx);

/* EC_POINTs_make_affine converts |num| points from |points| to affine form,
 * internally. It returns one on success and zero otherwise. If |ctx| is not
 * NULL, it may be used. */
OPENSSL_EXPORT int EC_POINTs_make_affine(const EC_GROUP *group, size_t num,
                                         EC_POINT *points[], BN_CTX *ctx);


/* Point conversion. */

/* EC_POINT_get_affine_coordinates_GFp sets |x| and |y| to the affine value of
 * |point| using |ctx|, if it's not NULL. It returns one on success and zero
 * otherwise. */
OPENSSL_EXPORT int EC_POINT_get_affine_coordinates_GFp(const EC_GROUP *group,
                                                       const EC_POINT *point,
                                                       BIGNUM *x, BIGNUM *y,
                                                       BN_CTX *ctx);

/* EC_POINT_set_affine_coordinates_GFp sets the value of |point| to be
 * (|x|, |y|). The |ctx| argument may be used if not NULL. It returns one
 * on success or zero on error. Note that, unlike with OpenSSL, it's
 * considered an error if the point is not on the curve. */
OPENSSL_EXPORT int EC_POINT_set_affine_coordinates_GFp(const EC_GROUP *group,
                                                       EC_POINT *point,
                                                       const BIGNUM *x,
                                                       const BIGNUM *y,
                                                       BN_CTX *ctx);

/* EC_POINT_point2oct serialises |point| into the X9.62 form given by |form|
 * into, at most, |len| bytes at |buf|. It returns the number of bytes written
 * or zero on error if |buf| is non-NULL, else the number of bytes needed. The
 * |ctx| argument may be used if not NULL. */
OPENSSL_EXPORT size_t EC_POINT_point2oct(const EC_GROUP *group,
                                         const EC_POINT *point,
                                         point_conversion_form_t form,
                                         uint8_t *buf, size_t len, BN_CTX *ctx);

/* EC_POINT_point2cbb behaves like |EC_POINT_point2oct| but appends the
 * serialised point to |cbb|. It returns one on success and zero on error. */
OPENSSL_EXPORT int EC_POINT_point2cbb(CBB *out, const EC_GROUP *group,
                                      const EC_POINT *point,
                                      point_conversion_form_t form,
                                      BN_CTX *ctx);

/* EC_POINT_oct2point sets |point| from |len| bytes of X9.62 format
 * serialisation in |buf|. It returns one on success and zero otherwise. The
 * |ctx| argument may be used if not NULL. */
OPENSSL_EXPORT int EC_POINT_oct2point(const EC_GROUP *group, EC_POINT *point,
                                      const uint8_t *buf, size_t len,
                                      BN_CTX *ctx);

/* EC_POINT_set_compressed_coordinates_GFp sets |point| to equal the point with
 * the given |x| coordinate and the y coordinate specified by |y_bit| (see
 * X9.62). It returns one on success and zero otherwise. */
OPENSSL_EXPORT int EC_POINT_set_compressed_coordinates_GFp(
    const EC_GROUP *group, EC_POINT *point, const BIGNUM *x, int y_bit,
    BN_CTX *ctx);


/* Group operations. */

/* EC_POINT_add sets |r| equal to |a| plus |b|. It returns one on success and
 * zero otherwise. If |ctx| is not NULL, it may be used. */
OPENSSL_EXPORT int EC_POINT_add(const EC_GROUP *group, EC_POINT *r,
                                const EC_POINT *a, const EC_POINT *b,
                                BN_CTX *ctx);

/* EC_POINT_dbl sets |r| equal to |a| plus |a|. It returns one on success and
 * zero otherwise. If |ctx| is not NULL, it may be used. */
OPENSSL_EXPORT int EC_POINT_dbl(const EC_GROUP *group, EC_POINT *r,
                                const EC_POINT *a, BN_CTX *ctx);

/* EC_POINT_invert sets |a| equal to minus |a|. It returns one on success and zero
 * otherwise. If |ctx| is not NULL, it may be used. */
OPENSSL_EXPORT int EC_POINT_invert(const EC_GROUP *group, EC_POINT *a,
                                   BN_CTX *ctx);

/* EC_POINT_mul sets r = generator*n + q*m. It returns one on success and zero
 * otherwise. If |ctx| is not NULL, it may be used. */
OPENSSL_EXPORT int EC_POINT_mul(const EC_GROUP *group, EC_POINT *r,
                                const BIGNUM *n, const EC_POINT *q,
                                const BIGNUM *m, BN_CTX *ctx);


/* Deprecated functions. */

/* EC_GROUP_new_curve_GFp creates a new, arbitrary elliptic curve group based
 * on the equation y² = x³ + a·x + b. It returns the new group or NULL on
 * error.
 *
 * This new group has no generator. It is an error to use a generator-less group
 * with any functions except for |EC_GROUP_free|, |EC_POINT_new|,
 * |EC_POINT_set_affine_coordinates_GFp|, and |EC_GROUP_set_generator|.
 *
 * |EC_GROUP|s returned by this function will always compare as unequal via
 * |EC_GROUP_cmp| (even to themselves). |EC_GROUP_get_curve_name| will always
 * return |NID_undef|.
 *
 * Avoid using arbitrary curves and use |EC_GROUP_new_by_curve_name| instead. */
OPENSSL_EXPORT EC_GROUP *EC_GROUP_new_curve_GFp(const BIGNUM *p,
                                                const BIGNUM *a,
                                                const BIGNUM *b, BN_CTX *ctx);

/* EC_GROUP_set_generator sets the generator for |group| to |generator|, which
 * must have the given order and cofactor. It may only be used with |EC_GROUP|
 * objects returned by |EC_GROUP_new_curve_GFp| and may only be used once on
 * each group. */
OPENSSL_EXPORT int EC_GROUP_set_generator(EC_GROUP *group,
                                          const EC_POINT *generator,
                                          const BIGNUM *order,
                                          const BIGNUM *cofactor);

/* EC_GROUP_get_order sets |*order| to the order of |group|, if it's not
 * NULL. It returns one on success and zero otherwise. |ctx| is ignored. Use
 * |EC_GROUP_get0_order| instead. */
OPENSSL_EXPORT int EC_GROUP_get_order(const EC_GROUP *group, BIGNUM *order,
                                      BN_CTX *ctx);

/* EC_GROUP_set_asn1_flag does nothing. */
OPENSSL_EXPORT void EC_GROUP_set_asn1_flag(EC_GROUP *group, int flag);

#define OPENSSL_EC_NAMED_CURVE 0

typedef struct ec_method_st EC_METHOD;

/* EC_GROUP_method_of returns NULL. */
OPENSSL_EXPORT const EC_METHOD *EC_GROUP_method_of(const EC_GROUP *group);

/* EC_METHOD_get_field_type returns NID_X9_62_prime_field. */
OPENSSL_EXPORT int EC_METHOD_get_field_type(const EC_METHOD *meth);

/* EC_GROUP_set_point_conversion_form aborts the process if |form| is not
 * |POINT_CONVERSION_UNCOMPRESSED| and otherwise does nothing. */
OPENSSL_EXPORT void EC_GROUP_set_point_conversion_form(
    EC_GROUP *group, point_conversion_form_t form);

/* EC_builtin_curve describes a supported elliptic curve. */
typedef struct {
  int nid;
  const char *comment;
} EC_builtin_curve;

/* EC_get_builtin_curves writes at most |max_num_curves| elements to
 * |out_curves| and returns the total number that it would have written, had
 * |max_num_curves| been large enough.
 *
 * The |EC_builtin_curve| items describe the supported elliptic curves. */
OPENSSL_EXPORT size_t EC_get_builtin_curves(EC_builtin_curve *out_curves,
                                            size_t max_num_curves);

/* Old code expects to get EC_KEY from ec.h. */
#include <openssl/ec_key.h>


#if defined(__cplusplus)
}  /* extern C */
#endif

#define EC_R_BUFFER_TOO_SMALL 100
#define EC_R_COORDINATES_OUT_OF_RANGE 101
#define EC_R_D2I_ECPKPARAMETERS_FAILURE 102
#define EC_R_EC_GROUP_NEW_BY_NAME_FAILURE 103
#define EC_R_GROUP2PKPARAMETERS_FAILURE 104
#define EC_R_I2D_ECPKPARAMETERS_FAILURE 105
#define EC_R_INCOMPATIBLE_OBJECTS 106
#define EC_R_INVALID_COMPRESSED_POINT 107
#define EC_R_INVALID_COMPRESSION_BIT 108
#define EC_R_INVALID_ENCODING 109
#define EC_R_INVALID_FIELD 110
#define EC_R_INVALID_FORM 111
#define EC_R_INVALID_GROUP_ORDER 112
#define EC_R_INVALID_PRIVATE_KEY 113
#define EC_R_MISSING_PARAMETERS 114
#define EC_R_MISSING_PRIVATE_KEY 115
#define EC_R_NON_NAMED_CURVE 116
#define EC_R_NOT_INITIALIZED 117
#define EC_R_PKPARAMETERS2GROUP_FAILURE 118
#define EC_R_POINT_AT_INFINITY 119
#define EC_R_POINT_IS_NOT_ON_CURVE 120
#define EC_R_SLOT_FULL 121
#define EC_R_UNDEFINED_GENERATOR 122
#define EC_R_UNKNOWN_GROUP 123
#define EC_R_UNKNOWN_ORDER 124
#define EC_R_WRONG_ORDER 125
#define EC_R_BIGNUM_OUT_OF_RANGE 126
#define EC_R_WRONG_CURVE_PARAMETERS 127
#define EC_R_DECODE_ERROR 128
#define EC_R_ENCODE_ERROR 129
#define EC_R_GROUP_MISMATCH 130
#define EC_R_INVALID_COFACTOR 131

#endif  /* OPENSSL_HEADER_EC_H */