text: /* fe_operations.h
   *
   * Copyright (C) 2006-2017 wolfSSL Inc.
   *
   * This file is part of wolfSSL.
   *
   * wolfSSL is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * wolfSSL is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
   */
  
  
  #ifndef WOLF_CRYPT_FE_OPERATIONS_H
  #define WOLF_CRYPT_FE_OPERATIONS_H
  
  #include "settings.h"
  
  #if defined(HAVE_CURVE25519) || defined(HAVE_ED25519)
  
  #if !defined(CURVE25519_SMALL) || !defined(ED25519_SMALL)
      #include <stdint.h>
  #endif
  
  #include "types.h"
  
  #if defined(USE_INTEL_SPEEDUP) && !defined(NO_CURVED25519_X64)
      #define CURVED25519_X64
  #elif defined(HAVE___UINT128_T) && !defined(NO_CURVED25519_128BIT)
      #define CURVED25519_128BIT
  #endif
  
  /*
  fe means field element.
  Here the field is \Z/(2^255-19).
  An element t, entries t[0]...t[9], represents the integer
  t[0]+2^26 t[1]+2^51 t[2]+2^77 t[3]+2^102 t[4]+...+2^230 t[9].
  Bounds on each t[i] vary depending on context.
  */
  
  #if defined(CURVE25519_SMALL) || defined(ED25519_SMALL)
      #define F25519_SIZE 32
  
      WOLFSSL_LOCAL void lm_copy(byte*, const byte*);
      WOLFSSL_LOCAL void lm_add(byte*, const byte*, const byte*);
      WOLFSSL_LOCAL void lm_sub(byte*, const byte*, const byte*);
      WOLFSSL_LOCAL void lm_neg(byte*,const byte*);
      WOLFSSL_LOCAL void lm_invert(byte*, const byte*);
      WOLFSSL_LOCAL void lm_mul(byte*,const byte*,const byte*);
  #endif
  
  
  #if !defined(FREESCALE_LTC_ECC)
  WOLFSSL_LOCAL void fe_init(void);
  
  WOLFSSL_LOCAL int  curve25519(byte * q, byte * n, byte * p);
  #endif
  
  /* default to be faster but take more memory */
  #if !defined(CURVE25519_SMALL) || !defined(ED25519_SMALL)
  
  #ifdef CURVED25519_X64
      typedef int64_t  fe[4];
  #elif defined(CURVED25519_128BIT)
      typedef int64_t  fe[5];
  #else
      typedef int32_t  fe[10];
  #endif
  
  WOLFSSL_LOCAL void fe_copy(fe, const fe);
  WOLFSSL_LOCAL void fe_add(fe, const fe, const fe);
  WOLFSSL_LOCAL void fe_neg(fe,const fe);
  WOLFSSL_LOCAL void fe_sub(fe, const fe, const fe);
  WOLFSSL_LOCAL void fe_invert(fe, const fe);
  WOLFSSL_LOCAL void fe_mul(fe,const fe,const fe);
  
  
  /* Based On Daniel J Bernstein's curve25519 and ed25519 Public Domain ref10
     work. */
  
  WOLFSSL_LOCAL void fe_0(fe);
  WOLFSSL_LOCAL void fe_1(fe);
  WOLFSSL_LOCAL int  fe_isnonzero(const fe);
  WOLFSSL_LOCAL int  fe_isnegative(const fe);
  WOLFSSL_LOCAL void fe_tobytes(unsigned char *, const fe);
  WOLFSSL_LOCAL void fe_sq(fe, const fe);
  WOLFSSL_LOCAL void fe_sq2(fe,const fe);
  WOLFSSL_LOCAL void fe_frombytes(fe,const unsigned char *);
  WOLFSSL_LOCAL void fe_cswap(fe,fe,unsigned int);
  WOLFSSL_LOCAL void fe_mul121666(fe,fe);
  WOLFSSL_LOCAL void fe_cmov(fe,const fe,unsigned int);
  WOLFSSL_LOCAL void fe_pow22523(fe,const fe);
  
  /* 64 type needed for SHA512 */
  WOLFSSL_LOCAL uint64_t load_3(const unsigned char *in);
  WOLFSSL_LOCAL uint64_t load_4(const unsigned char *in);
  
  #ifdef CURVED25519_X64
  WOLFSSL_LOCAL void fe_ge_to_p2(fe rx, fe ry, fe rz, const fe px, const fe py,
                                 const fe pz, const fe pt);
  WOLFSSL_LOCAL void fe_ge_to_p3(fe rx, fe ry, fe rz, fe rt, const fe px,
                                 const fe py, const fe pz, const fe pt);
  WOLFSSL_LOCAL void fe_ge_dbl(fe rx, fe ry, fe rz, fe rt, const fe px,
                               const fe py, const fe pz);
  WOLFSSL_LOCAL void fe_ge_madd(fe rx, fe ry, fe rz, fe rt, const fe px,
                                const fe py, const fe pz, const fe pt,
                                const fe qxy2d, const fe qyplusx,
                                const fe qyminusx);
  WOLFSSL_LOCAL void fe_ge_msub(fe rx, fe ry, fe rz, fe rt, const fe px,
                                const fe py, const fe pz, const fe pt,
                                const fe qxy2d, const fe qyplusx,
                                const fe qyminusx);
  WOLFSSL_LOCAL void fe_ge_add(fe rx, fe ry, fe rz, fe rt, const fe px,
                               const fe py, const fe pz, const fe pt, const fe qz,
                               const fe qt2d, const fe qyplusx,
                               const fe qyminusx);
  WOLFSSL_LOCAL void fe_ge_sub(fe rx, fe ry, fe rz, fe rt, const fe px,
                               const fe py, const fe pz, const fe pt, const fe qz,
                               const fe qt2d, const fe qyplusx,
                               const fe qyminusx);
  WOLFSSL_LOCAL void fe_cmov_table(fe* r, fe* base, signed char b);
  #endif /* CURVED25519_X64 */
  #endif /* !CURVE25519_SMALL || !ED25519_SMALL */
  
  /* Use less memory and only 32bit types or less, but is slower
     Based on Daniel Beer's public domain work. */
  #if defined(CURVE25519_SMALL) || defined(ED25519_SMALL)
  static const byte c25519_base_x[F25519_SIZE] = {9};
  static const byte f25519_zero[F25519_SIZE]   = {0};
  static const byte f25519_one[F25519_SIZE]    = {1};
  static const byte fprime_zero[F25519_SIZE]   = {0};
  static const byte fprime_one[F25519_SIZE]    = {1};
  
  WOLFSSL_LOCAL void fe_load(byte *x, word32 c);
  WOLFSSL_LOCAL void fe_normalize(byte *x);
  WOLFSSL_LOCAL void fe_inv__distinct(byte *r, const byte *x);
  
  /* Conditional copy. If condition == 0, then zero is copied to dst. If
   * condition == 1, then one is copied to dst. Any other value results in
   * undefined behavior.
   */
  WOLFSSL_LOCAL void fe_select(byte *dst, const byte *zero, const byte *one,
  		   byte condition);
  
  /* Multiply a point by a small constant. The two pointers are not
   * required to be distinct.
   *
   * The constant must be less than 2^24.
   */
  WOLFSSL_LOCAL void fe_mul_c(byte *r, const byte *a, word32 b);
  WOLFSSL_LOCAL void fe_mul__distinct(byte *r, const byte *a, const byte *b);
  
  /* Compute one of the square roots of the field element, if the element
   * is square. The other square is -r.
   *
   * If the input is not square, the returned value is a valid field
   * element, but not the correct answer. If you don't already know that
   * your element is square, you should square the return value and test.
   */
  WOLFSSL_LOCAL void fe_sqrt(byte *r, const byte *x);
  
  /* Conditional copy. If condition == 0, then zero is copied to dst. If
   * condition == 1, then one is copied to dst. Any other value results in
   * undefined behavior.
   */
  WOLFSSL_LOCAL void fprime_select(byte *dst, const byte *zero, const byte *one,
  		                         byte condition);
  WOLFSSL_LOCAL void fprime_add(byte *r, const byte *a, const byte *modulus);
  WOLFSSL_LOCAL void fprime_sub(byte *r, const byte *a, const byte *modulus);
  WOLFSSL_LOCAL void fprime_mul(byte *r, const byte *a, const byte *b,
  		                      const byte *modulus);
  WOLFSSL_LOCAL void fprime_copy(byte *x, const byte *a);
  
  #endif /* CURVE25519_SMALL || ED25519_SMALL */
  #endif /* HAVE_CURVE25519 || HAVE_ED25519 */
  
  #endif /* WOLF_CRYPT_FE_OPERATIONS_H */
  