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diff libtomcrypt/src/pk/ecc/ltc_ecc_projective_add_point.c @ 382:0cbe8f6dbf9e

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propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 2af22fb4e878750b88f80f90d439b316d229796f) to branch 'au.asn.ucc.matt.dropbear' (head 02c413252c90e9de8e03d91e9939dde3029f5c0a)
author Matt Johnston <matt@ucc.asn.au>
date Thu, 11 Jan 2007 02:41:05 +0000
parents
children f849a5ca2efc
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtomcrypt/src/pk/ecc/ltc_ecc_projective_add_point.c	Thu Jan 11 02:41:05 2007 +0000
@@ -0,0 +1,196 @@
+/* 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.
+ *
+ * Tom St Denis, [email protected], http://libtomcrypt.com
+ */
+
+/* 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(MECC) && (!defined(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
+
+/* $Source: /cvs/libtom/libtomcrypt/src/pk/ecc/ltc_ecc_projective_add_point.c,v $ */
+/* $Revision: 1.13 $ */
+/* $Date: 2006/12/04 05:07:59 $ */
+