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/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef __ecl_priv_h_
#define __ecl_priv_h_

#include "ecl.h"
#include "mpi.h"
#include "mplogic.h"

/* MAX_FIELD_SIZE_DIGITS is the maximum size of field element supported */
/* the following needs to go away... */
#if defined(MP_USE_LONG_LONG_DIGIT) || defined(MP_USE_LONG_DIGIT)
#define ECL_SIXTY_FOUR_BIT
#else
#define ECL_THIRTY_TWO_BIT
#endif

#define ECL_CURVE_DIGITS(curve_size_in_bits) \
	(((curve_size_in_bits)+(sizeof(mp_digit)*8-1))/(sizeof(mp_digit)*8))
#define ECL_BITS (sizeof(mp_digit)*8)
#define ECL_MAX_FIELD_SIZE_DIGITS (80/sizeof(mp_digit))

/* Gets the i'th bit in the binary representation of a. If i >= length(a), 
 * then return 0. (The above behaviour differs from mpl_get_bit, which
 * causes an error if i >= length(a).) */
#define MP_GET_BIT(a, i) \
	((i) >= mpl_significant_bits((a))) ? 0 : mpl_get_bit((a), (i))

#if !defined(MP_NO_MP_WORD) && !defined(MP_NO_ADD_WORD)
#define MP_ADD_CARRY(a1, a2, s, carry)   \
    { mp_word w; \
    w = ((mp_word)carry) + (a1) + (a2); \
    s = ACCUM(w); \
    carry = CARRYOUT(w); }

#define MP_SUB_BORROW(a1, a2, s, borrow)   \
    { mp_word w; \
    w = ((mp_word)(a1)) - (a2) - borrow; \
    s = ACCUM(w); \
    borrow = (w >> MP_DIGIT_BIT) & 1; }

#else
/* NOTE, 
 * carry and borrow are both read and written.
 * a1 or a2 and s could be the same variable.
 * don't trash those outputs until their respective inputs have
 * been read. */
#define MP_ADD_CARRY(a1, a2, s, carry)   \
    { mp_digit tmp,sum; \
    tmp = (a1); \
    sum = tmp + (a2); \
    tmp = (sum < tmp);                     /* detect overflow */ \
    s = sum += carry; \
    carry = tmp + (sum < carry); }

#define MP_SUB_BORROW(a1, a2, s, borrow)   \
    { mp_digit tmp; \
    tmp = (a1); \
    s = tmp - (a2); \
    tmp = (s > tmp);                    /* detect borrow */ \
    if (borrow && !s--) tmp++;	\
    borrow = tmp; }
#endif


struct GFMethodStr;
typedef struct GFMethodStr GFMethod;
struct GFMethodStr {
	/* Indicates whether the structure was constructed from dynamic memory 
	 * or statically created. */
	int constructed;
	/* Irreducible that defines the field. For prime fields, this is the
	 * prime p. For binary polynomial fields, this is the bitstring
	 * representation of the irreducible polynomial. */
	mp_int irr;
	/* For prime fields, the value irr_arr[0] is the number of bits in the 
	 * field. For binary polynomial fields, the irreducible polynomial
	 * f(t) is represented as an array of unsigned int[], where f(t) is
	 * of the form: f(t) = t^p[0] + t^p[1] + ... + t^p[4] where m = p[0]
	 * > p[1] > ... > p[4] = 0. */
	unsigned int irr_arr[5];
	/* Field arithmetic methods. All methods (except field_enc and
	 * field_dec) are assumed to take field-encoded parameters and return
	 * field-encoded values. All methods (except field_enc and field_dec)
	 * are required to be implemented. */
	mp_err (*field_add) (const mp_int *a, const mp_int *b, mp_int *r,
						 const GFMethod *meth);
	mp_err (*field_neg) (const mp_int *a, mp_int *r, const GFMethod *meth);
	mp_err (*field_sub) (const mp_int *a, const mp_int *b, mp_int *r,
						 const GFMethod *meth);
	mp_err (*field_mod) (const mp_int *a, mp_int *r, const GFMethod *meth);
	mp_err (*field_mul) (const mp_int *a, const mp_int *b, mp_int *r,
						 const GFMethod *meth);
	mp_err (*field_sqr) (const mp_int *a, mp_int *r, const GFMethod *meth);
	mp_err (*field_div) (const mp_int *a, const mp_int *b, mp_int *r,
						 const GFMethod *meth);
	mp_err (*field_enc) (const mp_int *a, mp_int *r, const GFMethod *meth);
	mp_err (*field_dec) (const mp_int *a, mp_int *r, const GFMethod *meth);
	/* Extra storage for implementation-specific data.  Any memory
	 * allocated to these extra fields will be cleared by extra_free. */
	void *extra1;
	void *extra2;
	void (*extra_free) (GFMethod *meth);
};

/* Construct generic GFMethods. */
GFMethod *GFMethod_consGFp(const mp_int *irr);
GFMethod *GFMethod_consGFp_mont(const mp_int *irr);
GFMethod *GFMethod_consGF2m(const mp_int *irr,
							const unsigned int irr_arr[5]);
/* Free the memory allocated (if any) to a GFMethod object. */
void GFMethod_free(GFMethod *meth);

struct ECGroupStr {
	/* Indicates whether the structure was constructed from dynamic memory 
	 * or statically created. */
	int constructed;
	/* Field definition and arithmetic. */
	GFMethod *meth;
	/* Textual representation of curve name, if any. */
	char *text;
	/* Curve parameters, field-encoded. */
	mp_int curvea, curveb;
	/* x and y coordinates of the base point, field-encoded. */
	mp_int genx, geny;
	/* Order and cofactor of the base point. */
	mp_int order;
	int cofactor;
	/* Point arithmetic methods. All methods are assumed to take
	 * field-encoded parameters and return field-encoded values. All
	 * methods (except base_point_mul and points_mul) are required to be
	 * implemented. */
	mp_err (*point_add) (const mp_int *px, const mp_int *py,
						 const mp_int *qx, const mp_int *qy, mp_int *rx,
						 mp_int *ry, const ECGroup *group);
	mp_err (*point_sub) (const mp_int *px, const mp_int *py,
						 const mp_int *qx, const mp_int *qy, mp_int *rx,
						 mp_int *ry, const ECGroup *group);
	mp_err (*point_dbl) (const mp_int *px, const mp_int *py, mp_int *rx,
						 mp_int *ry, const ECGroup *group);
	mp_err (*point_mul) (const mp_int *n, const mp_int *px,
						 const mp_int *py, mp_int *rx, mp_int *ry,
						 const ECGroup *group);
	mp_err (*base_point_mul) (const mp_int *n, mp_int *rx, mp_int *ry,
							  const ECGroup *group);
	mp_err (*points_mul) (const mp_int *k1, const mp_int *k2,
						  const mp_int *px, const mp_int *py, mp_int *rx,
						  mp_int *ry, const ECGroup *group);
	mp_err (*validate_point) (const mp_int *px, const mp_int *py, const ECGroup *group);
	/* Extra storage for implementation-specific data.  Any memory
	 * allocated to these extra fields will be cleared by extra_free. */
	void *extra1;
	void *extra2;
	void (*extra_free) (ECGroup *group);
};

/* Wrapper functions for generic prime field arithmetic. */
mp_err ec_GFp_add(const mp_int *a, const mp_int *b, mp_int *r,
				  const GFMethod *meth);
mp_err ec_GFp_neg(const mp_int *a, mp_int *r, const GFMethod *meth);
mp_err ec_GFp_sub(const mp_int *a, const mp_int *b, mp_int *r,
				  const GFMethod *meth);

/* fixed length in-line adds. Count is in words */
mp_err ec_GFp_add_3(const mp_int *a, const mp_int *b, mp_int *r,
				  const GFMethod *meth);
mp_err ec_GFp_add_4(const mp_int *a, const mp_int *b, mp_int *r,
				  const GFMethod *meth);
mp_err ec_GFp_add_5(const mp_int *a, const mp_int *b, mp_int *r,
				  const GFMethod *meth);
mp_err ec_GFp_add_6(const mp_int *a, const mp_int *b, mp_int *r,
				  const GFMethod *meth);
mp_err ec_GFp_sub_3(const mp_int *a, const mp_int *b, mp_int *r,
				  const GFMethod *meth);
mp_err ec_GFp_sub_4(const mp_int *a, const mp_int *b, mp_int *r,
				  const GFMethod *meth);
mp_err ec_GFp_sub_5(const mp_int *a, const mp_int *b, mp_int *r,
				  const GFMethod *meth);
mp_err ec_GFp_sub_6(const mp_int *a, const mp_int *b, mp_int *r,
				  const GFMethod *meth);

mp_err ec_GFp_mod(const mp_int *a, mp_int *r, const GFMethod *meth);
mp_err ec_GFp_mul(const mp_int *a, const mp_int *b, mp_int *r,
				  const GFMethod *meth);
mp_err ec_GFp_sqr(const mp_int *a, mp_int *r, const GFMethod *meth);
mp_err ec_GFp_div(const mp_int *a, const mp_int *b, mp_int *r,
				  const GFMethod *meth);
/* Wrapper functions for generic binary polynomial field arithmetic. */
mp_err ec_GF2m_add(const mp_int *a, const mp_int *b, mp_int *r,
				   const GFMethod *meth);
mp_err ec_GF2m_neg(const mp_int *a, mp_int *r, const GFMethod *meth);
mp_err ec_GF2m_mod(const mp_int *a, mp_int *r, const GFMethod *meth);
mp_err ec_GF2m_mul(const mp_int *a, const mp_int *b, mp_int *r,
				   const GFMethod *meth);
mp_err ec_GF2m_sqr(const mp_int *a, mp_int *r, const GFMethod *meth);
mp_err ec_GF2m_div(const mp_int *a, const mp_int *b, mp_int *r,
				   const GFMethod *meth);

/* Montgomery prime field arithmetic. */
mp_err ec_GFp_mul_mont(const mp_int *a, const mp_int *b, mp_int *r,
					   const GFMethod *meth);
mp_err ec_GFp_sqr_mont(const mp_int *a, mp_int *r, const GFMethod *meth);
mp_err ec_GFp_div_mont(const mp_int *a, const mp_int *b, mp_int *r,
					   const GFMethod *meth);
mp_err ec_GFp_enc_mont(const mp_int *a, mp_int *r, const GFMethod *meth);
mp_err ec_GFp_dec_mont(const mp_int *a, mp_int *r, const GFMethod *meth);
void ec_GFp_extra_free_mont(GFMethod *meth);

/* point multiplication */
mp_err ec_pts_mul_basic(const mp_int *k1, const mp_int *k2,
						const mp_int *px, const mp_int *py, mp_int *rx,
						mp_int *ry, const ECGroup *group);
mp_err ec_pts_mul_simul_w2(const mp_int *k1, const mp_int *k2,
						   const mp_int *px, const mp_int *py, mp_int *rx,
						   mp_int *ry, const ECGroup *group);

/* Computes the windowed non-adjacent-form (NAF) of a scalar. Out should
 * be an array of signed char's to output to, bitsize should be the number 
 * of bits of out, in is the original scalar, and w is the window size.
 * NAF is discussed in the paper: D. Hankerson, J. Hernandez and A.
 * Menezes, "Software implementation of elliptic curve cryptography over
 * binary fields", Proc. CHES 2000. */
mp_err ec_compute_wNAF(signed char *out, int bitsize, const mp_int *in,
					   int w);

/* Optimized field arithmetic */
mp_err ec_group_set_gfp192(ECGroup *group, ECCurveName);
mp_err ec_group_set_gfp224(ECGroup *group, ECCurveName);
mp_err ec_group_set_gfp256(ECGroup *group, ECCurveName);
mp_err ec_group_set_gfp384(ECGroup *group, ECCurveName);
mp_err ec_group_set_gfp521(ECGroup *group, ECCurveName);
mp_err ec_group_set_gf2m163(ECGroup *group, ECCurveName name);
mp_err ec_group_set_gf2m193(ECGroup *group, ECCurveName name);
mp_err ec_group_set_gf2m233(ECGroup *group, ECCurveName name);

/* Optimized point multiplication */
mp_err ec_group_set_gfp256_32(ECGroup *group, ECCurveName name);

/* Optimized floating-point arithmetic */
#ifdef ECL_USE_FP
mp_err ec_group_set_secp160r1_fp(ECGroup *group);
mp_err ec_group_set_nistp192_fp(ECGroup *group);
mp_err ec_group_set_nistp224_fp(ECGroup *group);
#endif

#endif							/* __ecl_priv_h_ */