--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtomcrypt/src/pk/ecc/ecc_import.c	Thu Jan 11 02:41:05 2007 +0000
@@ -0,0 +1,172 @@
+/* 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 ecc_import.c
+  ECC Crypto, Tom St Denis
+*/  
+
+#ifdef MECC
+
+static int is_point(ecc_key *key)
+{
+   void *prime, *b, *t1, *t2;
+   int err;
+   
+   if ((err = mp_init_multi(&prime, &b, &t1, &t2, NULL)) != CRYPT_OK) {
+      return err;
+   }
+   
+   /* load prime and b */
+   if ((err = mp_read_radix(prime, key->dp->prime, 16)) != CRYPT_OK)                          { goto error; }
+   if ((err = mp_read_radix(b, key->dp->B, 16)) != CRYPT_OK)                                  { goto error; }
+   
+   /* compute y^2 */
+   if ((err = mp_sqr(key->pubkey.y, t1)) != CRYPT_OK)                                         { goto error; }
+   
+   /* compute x^3 */
+   if ((err = mp_sqr(key->pubkey.x, t2)) != CRYPT_OK)                                         { goto error; }
+   if ((err = mp_mod(t2, prime, t2)) != CRYPT_OK)                                             { goto error; }
+   if ((err = mp_mul(key->pubkey.x, t2, t2)) != CRYPT_OK)                                     { goto error; }
+   
+   /* compute y^2 - x^3 */
+   if ((err = mp_sub(t1, t2, t1)) != CRYPT_OK)                                                { goto error; }
+   
+   /* compute y^2 - x^3 + 3x */
+   if ((err = mp_add(t1, key->pubkey.x, t1)) != CRYPT_OK)                                     { goto error; }
+   if ((err = mp_add(t1, key->pubkey.x, t1)) != CRYPT_OK)                                     { goto error; }
+   if ((err = mp_add(t1, key->pubkey.x, t1)) != CRYPT_OK)                                     { goto error; }
+   if ((err = mp_mod(t1, prime, t1)) != CRYPT_OK)                                             { goto error; }
+   while (mp_cmp_d(t1, 0) == LTC_MP_LT) {
+      if ((err = mp_add(t1, prime, t1)) != CRYPT_OK)                                          { goto error; }
+   }
+   while (mp_cmp(t1, prime) != LTC_MP_LT) {
+      if ((err = mp_sub(t1, prime, t1)) != CRYPT_OK)                                          { goto error; }
+   }
+   
+   /* compare to b */
+   if (mp_cmp(t1, b) != LTC_MP_EQ) {
+      err = CRYPT_INVALID_PACKET;
+   } else {
+      err = CRYPT_OK;
+   }
+   
+error:
+   mp_clear_multi(prime, b, t1, t2, NULL);
+   return err;
+}
+
+/**
+  Import an ECC key from a binary packet
+  @param in      The packet to import
+  @param inlen   The length of the packet
+  @param key     [out] The destination of the import
+  @return CRYPT_OK if successful, upon error all allocated memory will be freed
+*/
+int ecc_import(const unsigned char *in, unsigned long inlen, ecc_key *key)
+{
+   return ecc_import_ex(in, inlen, key, NULL);
+}
+
+/**
+  Import an ECC key from a binary packet, using user supplied domain params rather than one of the NIST ones
+  @param in      The packet to import
+  @param inlen   The length of the packet
+  @param key     [out] The destination of the import
+  @param dp      pointer to user supplied params; must be the same as the params used when exporting
+  @return CRYPT_OK if successful, upon error all allocated memory will be freed
+*/
+int ecc_import_ex(const unsigned char *in, unsigned long inlen, ecc_key *key, const ltc_ecc_set_type *dp)
+{
+   unsigned long key_size;
+   unsigned char flags[1];
+   int           err;
+
+   LTC_ARGCHK(in  != NULL);
+   LTC_ARGCHK(key != NULL);
+   LTC_ARGCHK(ltc_mp.name != NULL);
+
+   /* init key */
+   if (mp_init_multi(&key->pubkey.x, &key->pubkey.y, &key->pubkey.z, &key->k, NULL) != CRYPT_OK) {
+      return CRYPT_MEM;
+   }
+
+   /* find out what type of key it is */
+   if ((err = der_decode_sequence_multi(in, inlen, 
+                                  LTC_ASN1_BIT_STRING, 1UL, &flags,
+                                  LTC_ASN1_EOL,        0UL, NULL)) != CRYPT_OK) {
+      goto done;
+   }
+
+
+   if (flags[0] == 1) {
+      /* private key */
+      key->type = PK_PRIVATE;
+      if ((err = der_decode_sequence_multi(in, inlen,
+                                     LTC_ASN1_BIT_STRING,      1UL, flags,
+                                     LTC_ASN1_SHORT_INTEGER,   1UL, &key_size,
+                                     LTC_ASN1_INTEGER,         1UL, key->pubkey.x,
+                                     LTC_ASN1_INTEGER,         1UL, key->pubkey.y,
+                                     LTC_ASN1_INTEGER,         1UL, key->k,
+                                     LTC_ASN1_EOL,             0UL, NULL)) != CRYPT_OK) {
+         goto done;
+      }
+   } else {
+      /* public key */
+      key->type = PK_PUBLIC;
+      if ((err = der_decode_sequence_multi(in, inlen,
+                                     LTC_ASN1_BIT_STRING,      1UL, flags,
+                                     LTC_ASN1_SHORT_INTEGER,   1UL, &key_size,
+                                     LTC_ASN1_INTEGER,         1UL, key->pubkey.x,
+                                     LTC_ASN1_INTEGER,         1UL, key->pubkey.y,
+                                     LTC_ASN1_EOL,             0UL, NULL)) != CRYPT_OK) {
+         goto done;
+      }
+   }
+
+   if (dp == NULL) {
+     /* find the idx */
+     for (key->idx = 0; ltc_ecc_sets[key->idx].size && (unsigned long)ltc_ecc_sets[key->idx].size != key_size; ++key->idx);
+     if (ltc_ecc_sets[key->idx].size == 0) {
+       err = CRYPT_INVALID_PACKET;
+       goto done;
+     }
+     key->dp = &ltc_ecc_sets[key->idx];
+   } else {
+     key->idx = -1;
+     key->dp = dp;
+   }
+   /* set z */
+   if ((err = mp_set(key->pubkey.z, 1)) != CRYPT_OK) { goto done; }
+   
+   /* is it a point on the curve?  */
+   if ((err = is_point(key)) != CRYPT_OK) {
+      goto done;
+   }
+
+   /* we're good */
+   return CRYPT_OK;
+done:
+   mp_clear_multi(key->pubkey.x, key->pubkey.y, key->pubkey.z, key->k, NULL);
+   return err;
+}
+#endif
+/* $Source: /cvs/libtom/libtomcrypt/src/pk/ecc/ecc_import.c,v $ */
+/* $Revision: 1.11 $ */
+/* $Date: 2006/12/04 02:19:48 $ */
+