--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtomcrypt/src/pk/ecc/ltc_ecc_map.c	Sun Sep 14 06:47:51 2008 +0000
@@ -0,0 +1,76 @@
+/* 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_map.c
+  ECC Crypto, Tom St Denis
+*/  
+
+#ifdef MECC
+
+/**
+  Map a projective jacbobian point back to affine space
+  @param P        [in/out] The point to map
+  @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_map(ecc_point *P, void *modulus, void *mp)
+{
+   void *t1, *t2;
+   int   err;
+
+   LTC_ARGCHK(P       != NULL);
+   LTC_ARGCHK(modulus != NULL);
+   LTC_ARGCHK(mp      != NULL);
+
+   if ((err = mp_init_multi(&t1, &t2, NULL)) != CRYPT_OK) {
+      return CRYPT_MEM;
+   }
+
+   /* first map z back to normal */
+   if ((err = mp_montgomery_reduce(P->z, modulus, mp)) != CRYPT_OK)           { goto done; }
+
+   /* get 1/z */
+   if ((err = mp_invmod(P->z, modulus, t1)) != CRYPT_OK)                      { goto done; }
+ 
+   /* get 1/z^2 and 1/z^3 */
+   if ((err = mp_sqr(t1, t2)) != CRYPT_OK)                                    { goto done; }
+   if ((err = mp_mod(t2, modulus, t2)) != CRYPT_OK)                           { goto done; }
+   if ((err = mp_mul(t1, t2, t1)) != CRYPT_OK)                                { goto done; }
+   if ((err = mp_mod(t1, modulus, t1)) != CRYPT_OK)                           { goto done; }
+
+   /* multiply against x/y */
+   if ((err = mp_mul(P->x, t2, P->x)) != CRYPT_OK)                            { goto done; }
+   if ((err = mp_montgomery_reduce(P->x, modulus, mp)) != CRYPT_OK)           { goto done; }
+   if ((err = mp_mul(P->y, t1, P->y)) != CRYPT_OK)                            { goto done; }
+   if ((err = mp_montgomery_reduce(P->y, modulus, mp)) != CRYPT_OK)           { goto done; }
+   if ((err = mp_set(P->z, 1)) != CRYPT_OK)                                   { goto done; }
+
+   err = CRYPT_OK;
+done:
+   mp_clear_multi(t1, t2, NULL);
+   return err;
+}
+
+#endif
+
+/* $Source: /cvs/libtom/libtomcrypt/src/pk/ecc/ltc_ecc_map.c,v $ */
+/* $Revision: 1.5 $ */
+/* $Date: 2006/12/04 02:50:11 $ */
+