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view libtomcrypt/src/pk/ecc/ltc_ecc_projective_add_point.c @ 1653:76189c9ffea2

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External Public-Key Authentication API (#72) * Implemented dynamic loading of an external plug-in shared library to delegate public key authentication * Moved conditional compilation of the plugin infrastructure into the configure.ac script to be able to add -ldl to dropbear build only when the flag is enabled * Added tags file to the ignore list * Updated API to have the constructor to return function pointers in the pliugin instance. Added support for passing user name to the checkpubkey function. Added options to the session returned by the plugin and have dropbear to parse and process them * Added -rdynamic to the linker flags when EPKA is enabled * Changed the API to pass a previously created session to the checkPubKey function (created during preauth) * Added documentation to the API * Added parameter addrstring to plugin creation function * Modified the API to retrieve the auth options. Instead of having them as field of the EPKASession struct, they are stored internally (plugin-dependent) in the plugin/session and retrieved through a pointer to a function (in the session) * Changed option string to be a simple char * instead of unsigned char *
author fabriziobertocci <fabriziobertocci@gmail.com>
date Wed, 15 May 2019 09:43:57 -0400
parents 6dba84798cd5
children
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/* LibTomCrypt, modular cryptographic library -- Tom St Denis
 *
 * LibTomCrypt is a library that provides various cryptographic
 * algorithms in a highly modular and flexible manner.
 *
 * The library is free for all purposes without any express
 * guarantee it works.
 */

/* Implements ECC over Z/pZ for curve y^2 = x^3 - 3x + b
 *
 * All curves taken from NIST recommendation paper of July 1999
 * Available at http://csrc.nist.gov/cryptval/dss.htm
 */
#include "tomcrypt.h"

/**
  @file ltc_ecc_projective_add_point.c
  ECC Crypto, Tom St Denis
*/

#if defined(LTC_MECC) && (!defined(LTC_MECC_ACCEL) || defined(LTM_DESC))

/**
   Add two ECC points
   @param P        The point to add
   @param Q        The point to add
   @param R        [out] The destination of the double
   @param modulus  The modulus of the field the ECC curve is in
   @param mp       The "b" value from montgomery_setup()
   @return CRYPT_OK on success
*/
int ltc_ecc_projective_add_point(ecc_point *P, ecc_point *Q, ecc_point *R, void *modulus, void *mp)
{
   void  *t1, *t2, *x, *y, *z;
   int    err;

   LTC_ARGCHK(P       != NULL);
   LTC_ARGCHK(Q       != NULL);
   LTC_ARGCHK(R       != NULL);
   LTC_ARGCHK(modulus != NULL);
   LTC_ARGCHK(mp      != NULL);

   if ((err = mp_init_multi(&t1, &t2, &x, &y, &z, NULL)) != CRYPT_OK) {
      return err;
   }

   /* should we dbl instead? */
   if ((err = mp_sub(modulus, Q->y, t1)) != CRYPT_OK)                          { goto done; }

   if ( (mp_cmp(P->x, Q->x) == LTC_MP_EQ) &&
        (Q->z != NULL && mp_cmp(P->z, Q->z) == LTC_MP_EQ) &&
        (mp_cmp(P->y, Q->y) == LTC_MP_EQ || mp_cmp(P->y, t1) == LTC_MP_EQ)) {
        mp_clear_multi(t1, t2, x, y, z, NULL);
        return ltc_ecc_projective_dbl_point(P, R, modulus, mp);
   }

   if ((err = mp_copy(P->x, x)) != CRYPT_OK)                                   { goto done; }
   if ((err = mp_copy(P->y, y)) != CRYPT_OK)                                   { goto done; }
   if ((err = mp_copy(P->z, z)) != CRYPT_OK)                                   { goto done; }

   /* if Z is one then these are no-operations */
   if (Q->z != NULL) {
      /* T1 = Z' * Z' */
      if ((err = mp_sqr(Q->z, t1)) != CRYPT_OK)                                { goto done; }
      if ((err = mp_montgomery_reduce(t1, modulus, mp)) != CRYPT_OK)           { goto done; }
      /* X = X * T1 */
      if ((err = mp_mul(t1, x, x)) != CRYPT_OK)                                { goto done; }
      if ((err = mp_montgomery_reduce(x, modulus, mp)) != CRYPT_OK)            { goto done; }
      /* T1 = Z' * T1 */
      if ((err = mp_mul(Q->z, t1, t1)) != CRYPT_OK)                            { goto done; }
      if ((err = mp_montgomery_reduce(t1, modulus, mp)) != CRYPT_OK)           { goto done; }
      /* Y = Y * T1 */
      if ((err = mp_mul(t1, y, y)) != CRYPT_OK)                                { goto done; }
      if ((err = mp_montgomery_reduce(y, modulus, mp)) != CRYPT_OK)            { goto done; }
   }

   /* T1 = Z*Z */
   if ((err = mp_sqr(z, t1)) != CRYPT_OK)                                      { goto done; }
   if ((err = mp_montgomery_reduce(t1, modulus, mp)) != CRYPT_OK)              { goto done; }
   /* T2 = X' * T1 */
   if ((err = mp_mul(Q->x, t1, t2)) != CRYPT_OK)                               { goto done; }
   if ((err = mp_montgomery_reduce(t2, modulus, mp)) != CRYPT_OK)              { goto done; }
   /* T1 = Z * T1 */
   if ((err = mp_mul(z, t1, t1)) != CRYPT_OK)                                  { goto done; }
   if ((err = mp_montgomery_reduce(t1, modulus, mp)) != CRYPT_OK)              { goto done; }
   /* T1 = Y' * T1 */
   if ((err = mp_mul(Q->y, t1, t1)) != CRYPT_OK)                               { goto done; }
   if ((err = mp_montgomery_reduce(t1, modulus, mp)) != CRYPT_OK)              { goto done; }

   /* Y = Y - T1 */
   if ((err = mp_sub(y, t1, y)) != CRYPT_OK)                                   { goto done; }
   if (mp_cmp_d(y, 0) == LTC_MP_LT) {
      if ((err = mp_add(y, modulus, y)) != CRYPT_OK)                           { goto done; }
   }
   /* T1 = 2T1 */
   if ((err = mp_add(t1, t1, t1)) != CRYPT_OK)                                 { goto done; }
   if (mp_cmp(t1, modulus) != LTC_MP_LT) {
      if ((err = mp_sub(t1, modulus, t1)) != CRYPT_OK)                         { goto done; }
   }
   /* T1 = Y + T1 */
   if ((err = mp_add(t1, y, t1)) != CRYPT_OK)                                  { goto done; }
   if (mp_cmp(t1, modulus) != LTC_MP_LT) {
      if ((err = mp_sub(t1, modulus, t1)) != CRYPT_OK)                         { goto done; }
   }
   /* X = X - T2 */
   if ((err = mp_sub(x, t2, x)) != CRYPT_OK)                                   { goto done; }
   if (mp_cmp_d(x, 0) == LTC_MP_LT) {
      if ((err = mp_add(x, modulus, x)) != CRYPT_OK)                           { goto done; }
   }
   /* T2 = 2T2 */
   if ((err = mp_add(t2, t2, t2)) != CRYPT_OK)                                 { goto done; }
   if (mp_cmp(t2, modulus) != LTC_MP_LT) {
      if ((err = mp_sub(t2, modulus, t2)) != CRYPT_OK)                         { goto done; }
   }
   /* T2 = X + T2 */
   if ((err = mp_add(t2, x, t2)) != CRYPT_OK)                                  { goto done; }
   if (mp_cmp(t2, modulus) != LTC_MP_LT) {
      if ((err = mp_sub(t2, modulus, t2)) != CRYPT_OK)                         { goto done; }
   }

   /* if Z' != 1 */
   if (Q->z != NULL) {
      /* Z = Z * Z' */
      if ((err = mp_mul(z, Q->z, z)) != CRYPT_OK)                              { goto done; }
      if ((err = mp_montgomery_reduce(z, modulus, mp)) != CRYPT_OK)            { goto done; }
   }

   /* Z = Z * X */
   if ((err = mp_mul(z, x, z)) != CRYPT_OK)                                    { goto done; }
   if ((err = mp_montgomery_reduce(z, modulus, mp)) != CRYPT_OK)               { goto done; }

   /* T1 = T1 * X  */
   if ((err = mp_mul(t1, x, t1)) != CRYPT_OK)                                  { goto done; }
   if ((err = mp_montgomery_reduce(t1, modulus, mp)) != CRYPT_OK)              { goto done; }
   /* X = X * X */
   if ((err = mp_sqr(x, x)) != CRYPT_OK)                                       { goto done; }
   if ((err = mp_montgomery_reduce(x, modulus, mp)) != CRYPT_OK)               { goto done; }
   /* T2 = T2 * x */
   if ((err = mp_mul(t2, x, t2)) != CRYPT_OK)                                  { goto done; }
   if ((err = mp_montgomery_reduce(t2, modulus, mp)) != CRYPT_OK)              { goto done; }
   /* T1 = T1 * X  */
   if ((err = mp_mul(t1, x, t1)) != CRYPT_OK)                                  { goto done; }
   if ((err = mp_montgomery_reduce(t1, modulus, mp)) != CRYPT_OK)              { goto done; }

   /* X = Y*Y */
   if ((err = mp_sqr(y, x)) != CRYPT_OK)                                       { goto done; }
   if ((err = mp_montgomery_reduce(x, modulus, mp)) != CRYPT_OK)               { goto done; }
   /* X = X - T2 */
   if ((err = mp_sub(x, t2, x)) != CRYPT_OK)                                   { goto done; }
   if (mp_cmp_d(x, 0) == LTC_MP_LT) {
      if ((err = mp_add(x, modulus, x)) != CRYPT_OK)                           { goto done; }
   }

   /* T2 = T2 - X */
   if ((err = mp_sub(t2, x, t2)) != CRYPT_OK)                                  { goto done; }
   if (mp_cmp_d(t2, 0) == LTC_MP_LT) {
      if ((err = mp_add(t2, modulus, t2)) != CRYPT_OK)                         { goto done; }
   }
   /* T2 = T2 - X */
   if ((err = mp_sub(t2, x, t2)) != CRYPT_OK)                                  { goto done; }
   if (mp_cmp_d(t2, 0) == LTC_MP_LT) {
      if ((err = mp_add(t2, modulus, t2)) != CRYPT_OK)                         { goto done; }
   }
   /* T2 = T2 * Y */
   if ((err = mp_mul(t2, y, t2)) != CRYPT_OK)                                  { goto done; }
   if ((err = mp_montgomery_reduce(t2, modulus, mp)) != CRYPT_OK)              { goto done; }
   /* Y = T2 - T1 */
   if ((err = mp_sub(t2, t1, y)) != CRYPT_OK)                                  { goto done; }
   if (mp_cmp_d(y, 0) == LTC_MP_LT) {
      if ((err = mp_add(y, modulus, y)) != CRYPT_OK)                           { goto done; }
   }
   /* Y = Y/2 */
   if (mp_isodd(y)) {
      if ((err = mp_add(y, modulus, y)) != CRYPT_OK)                           { goto done; }
   }
   if ((err = mp_div_2(y, y)) != CRYPT_OK)                                     { goto done; }

   if ((err = mp_copy(x, R->x)) != CRYPT_OK)                                   { goto done; }
   if ((err = mp_copy(y, R->y)) != CRYPT_OK)                                   { goto done; }
   if ((err = mp_copy(z, R->z)) != CRYPT_OK)                                   { goto done; }

   err = CRYPT_OK;
done:
   mp_clear_multi(t1, t2, x, y, z, NULL);
   return err;
}

#endif

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