/* 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@iahu.ca, http://libtomcrypt.org */#include "mycrypt.h"#ifdef MRSA/* PSS pad then sign */int rsa_sign_hash(const unsigned char *msghash,  unsigned long  msghashlen,                         unsigned char *sig,      unsigned long *siglen,                         prng_state    *prng,     int            prng_idx,                        int            hash_idx, unsigned long  saltlen,                        rsa_key *key){   unsigned long modulus_bitlen, modulus_bytelen, x;   int           err;     _ARGCHK(msghash  != NULL);  _ARGCHK(sig      != NULL);  _ARGCHK(siglen   != NULL);  _ARGCHK(key      != NULL);    /* valid prng and hash ? */  if ((err = prng_is_valid(prng_idx)) != CRYPT_OK) {     return err;  }  if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) {     return err;  }    /* get modulus len in bits */  modulus_bitlen = mp_count_bits(&(key->N));  /* outlen must be at least the size of the modulus */  modulus_bytelen = mp_unsigned_bin_size(&(key->N));  if (modulus_bytelen > *siglen) {     return CRYPT_BUFFER_OVERFLOW;  }        /* PSS pad the key */  x = *siglen;  if ((err = pkcs_1_pss_encode(msghash, msghashlen, saltlen, prng, prng_idx,                               hash_idx, modulus_bitlen, sig, &x)) != CRYPT_OK) {     return err;  }  /* RSA encode it */  return rsa_exptmod(sig, x, sig, siglen, PK_PRIVATE, prng, prng_idx, key);}#endif /* MRSA */