--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtomcrypt/src/pk/ecc/ecc_sign_hash.c	Thu Feb 22 14:53:49 2007 +0000
@@ -0,0 +1,114 @@
+/* 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_sign_hash.c
+  ECC Crypto, Tom St Denis
+*/  
+
+#ifdef MECC
+
+/**
+  Sign a message digest
+  @param in        The message digest to sign
+  @param inlen     The length of the digest
+  @param out       [out] The destination for the signature
+  @param outlen    [in/out] The max size and resulting size of the signature
+  @param prng      An active PRNG state
+  @param wprng     The index of the PRNG you wish to use
+  @param key       A private ECC key
+  @return CRYPT_OK if successful
+*/
+int ecc_sign_hash(const unsigned char *in,  unsigned long inlen, 
+                        unsigned char *out, unsigned long *outlen, 
+                        prng_state *prng, int wprng, ecc_key *key)
+{
+   ecc_key       pubkey;
+   void          *r, *s, *e, *p;
+   int           err;
+
+   LTC_ARGCHK(in     != NULL);
+   LTC_ARGCHK(out    != NULL);
+   LTC_ARGCHK(outlen != NULL);
+   LTC_ARGCHK(key    != NULL);
+
+   /* is this a private key? */
+   if (key->type != PK_PRIVATE) {
+      return CRYPT_PK_NOT_PRIVATE;
+   }
+   
+   /* is the IDX valid ?  */
+   if (ltc_ecc_is_valid_idx(key->idx) != 1) {
+      return CRYPT_PK_INVALID_TYPE;
+   }
+   
+   if ((err = prng_is_valid(wprng)) != CRYPT_OK) {
+      return err;
+   }
+
+   /* get the hash and load it as a bignum into 'e' */
+   /* init the bignums */
+   if ((err = mp_init_multi(&r, &s, &p, &e, NULL)) != CRYPT_OK) { 
+      return err;
+   }
+   if ((err = mp_read_radix(p, (char *)key->dp->order, 16)) != CRYPT_OK)                      { goto errnokey; }
+   if ((err = mp_read_unsigned_bin(e, (unsigned char *)in, (int)inlen)) != CRYPT_OK)          { goto errnokey; }
+
+   /* make up a key and export the public copy */
+   for (;;) {
+      if ((err = ecc_make_key_ex(prng, wprng, &pubkey, key->dp)) != CRYPT_OK) {
+         goto errnokey;
+      }
+
+      /* find r = x1 mod n */
+      if ((err = mp_mod(pubkey.pubkey.x, p, r)) != CRYPT_OK)                 { goto error; }
+
+      if (mp_iszero(r) == LTC_MP_YES) {
+         ecc_free(&pubkey);
+      } else { 
+        /* find s = (e + xr)/k */
+        if ((err = mp_invmod(pubkey.k, p, pubkey.k)) != CRYPT_OK)            { goto error; } /* k = 1/k */
+        if ((err = mp_mulmod(key->k, r, p, s)) != CRYPT_OK)                  { goto error; } /* s = xr */
+        if ((err = mp_add(e, s, s)) != CRYPT_OK)                             { goto error; } /* s = e +  xr */
+        if ((err = mp_mod(s, p, s)) != CRYPT_OK)                             { goto error; } /* s = e +  xr */
+        if ((err = mp_mulmod(s, pubkey.k, p, s)) != CRYPT_OK)                { goto error; } /* s = (e + xr)/k */
+        ecc_free(&pubkey);
+        if (mp_iszero(s) == LTC_MP_NO) {
+           break;
+        }
+      }
+   }
+
+   /* store as SEQUENCE { r, s -- integer } */
+   err = der_encode_sequence_multi(out, outlen,
+                             LTC_ASN1_INTEGER, 1UL, r,
+                             LTC_ASN1_INTEGER, 1UL, s,
+                             LTC_ASN1_EOL, 0UL, NULL);
+   goto errnokey;
+error:
+   ecc_free(&pubkey);
+errnokey:
+   mp_clear_multi(r, s, p, e, NULL);
+   return err;   
+}
+
+#endif
+/* $Source: /cvs/libtom/libtomcrypt/src/pk/ecc/ecc_sign_hash.c,v $ */
+/* $Revision: 1.9 $ */
+/* $Date: 2006/12/04 02:50:11 $ */
+