/* 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, tomstdenis@gmail.com, http://libtomcrypt.com */#include "tomcrypt.h"/**   @file dsa_sign_hash.c   DSA implementation, sign a hash, Tom St Denis*/#ifdef MDSA/**  Sign a hash with DSA  @param in       The hash to sign  @param inlen    The length of the hash to sign  @param r        The "r" integer of the signature (caller must initialize with mp_init() first)  @param s        The "s" integer of the signature (caller must initialize with mp_init() first)  @param prng     An active PRNG state  @param wprng    The index of the PRNG desired  @param key      A private DSA key  @return CRYPT_OK if successful*/int dsa_sign_hash_raw(const unsigned char *in,  unsigned long inlen,                                   void   *r,   void *s,                               prng_state *prng, int wprng, dsa_key *key){   void         *k, *kinv, *tmp;   unsigned char *buf;   int            err;   LTC_ARGCHK(in  != NULL);   LTC_ARGCHK(r   != NULL);   LTC_ARGCHK(s   != NULL);   LTC_ARGCHK(key != NULL);   if ((err = prng_is_valid(wprng)) != CRYPT_OK) {      return err;   }   if (key->type != PK_PRIVATE) {      return CRYPT_PK_NOT_PRIVATE;   }   /* check group order size  */   if (key->qord >= MDSA_MAX_GROUP) {      return CRYPT_INVALID_ARG;   }   buf = XMALLOC(MDSA_MAX_GROUP);   if (buf == NULL) {      return CRYPT_MEM;   }   /* Init our temps */   if ((err = mp_init_multi(&k, &kinv, &tmp, NULL)) != CRYPT_OK)                       { goto ERRBUF; }retry:   do {      /* gen random k */      if (prng_descriptor[wprng].read(buf, key->qord, prng) != (unsigned long)key->qord) {         err = CRYPT_ERROR_READPRNG;         goto error;      }      /* read k */      if ((err = mp_read_unsigned_bin(k, buf, key->qord)) != CRYPT_OK)                 { goto error; }      /* k > 1 ? */      if (mp_cmp_d(k, 1) != LTC_MP_GT)                                                 { goto retry; }      /* test gcd */      if ((err = mp_gcd(k, key->q, tmp)) != CRYPT_OK)                                  { goto error; }   } while (mp_cmp_d(tmp, 1) != LTC_MP_EQ);   /* now find 1/k mod q */   if ((err = mp_invmod(k, key->q, kinv)) != CRYPT_OK)                                 { goto error; }   /* now find r = g^k mod p mod q */   if ((err = mp_exptmod(key->g, k, key->p, r)) != CRYPT_OK)                           { goto error; }   if ((err = mp_mod(r, key->q, r)) != CRYPT_OK)                                       { goto error; }   if (mp_iszero(r) == LTC_MP_YES)                                                     { goto retry; }   /* now find s = (in + xr)/k mod q */   if ((err = mp_read_unsigned_bin(tmp, (unsigned char *)in, inlen)) != CRYPT_OK)      { goto error; }   if ((err = mp_mul(key->x, r, s)) != CRYPT_OK)                                       { goto error; }   if ((err = mp_add(s, tmp, s)) != CRYPT_OK)                                          { goto error; }   if ((err = mp_mulmod(s, kinv, key->q, s)) != CRYPT_OK)                              { goto error; }   if (mp_iszero(s) == LTC_MP_YES)                                                     { goto retry; }   err = CRYPT_OK;error:    mp_clear_multi(k, kinv, tmp, NULL);ERRBUF:#ifdef LTC_CLEAN_STACK   zeromem(buf, MDSA_MAX_GROUP);#endif   XFREE(buf);   return err;}/**  Sign a hash with DSA  @param in       The hash to sign  @param inlen    The length of the hash to sign  @param out      [out] Where to store 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 desired  @param key      A private DSA key  @return CRYPT_OK if successful*/int dsa_sign_hash(const unsigned char *in,  unsigned long inlen,                        unsigned char *out, unsigned long *outlen,                        prng_state *prng, int wprng, dsa_key *key){   void         *r, *s;   int           err;   LTC_ARGCHK(in      != NULL);   LTC_ARGCHK(out     != NULL);   LTC_ARGCHK(outlen  != NULL);   LTC_ARGCHK(key     != NULL);   if (mp_init_multi(&r, &s, NULL) != CRYPT_OK) {      return CRYPT_MEM;   }   if ((err = dsa_sign_hash_raw(in, inlen, r, s, prng, wprng, key)) != CRYPT_OK) {      goto error;   }   err = der_encode_sequence_multi(out, outlen,                              LTC_ASN1_INTEGER, 1UL, r,                              LTC_ASN1_INTEGER, 1UL, s,                              LTC_ASN1_EOL,     0UL, NULL);error:   mp_clear_multi(r, s, NULL);   return err;}#endif/* $Source: /cvs/libtom/libtomcrypt/src/pk/dsa/dsa_sign_hash.c,v $ *//* $Revision: 1.12 $ *//* $Date: 2006/12/04 22:27:56 $ */