view libtomcrypt/src/pk/ecc/ecc_sign_hash.c @ 447:278805938dcf

Patch from Nicolai Ehemann to try binding before going to the background, so that if it exits early (because something's already listening etc) then it will return an exitcode of 1.
author Matt Johnston <matt@ucc.asn.au>
date Thu, 19 Jul 2007 15:54:18 +0000
parents 0cbe8f6dbf9e
children ac2158e3e403
line wrap: on
line source

/* 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 $ */