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/* 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.org
*/
#include "tomcrypt.h"
/**
@file rsa_sign_hash.c
RSA PKCS v2 PSS sign hash, Tom St Denis
*/
#ifdef MRSA
/**
(PKCS #1, v2.0) PSS pad then sign
@param in The hash to sign
@param inlen The length of the hash to sign (octets)
@param out [out] The signature
@param outlen [in/out] The max size and resulting size of the signature
@param prng An active PRNG state
@param prng_idx The index of the PRNG desired
@param hash_idx The index of the hash desired
@param saltlen The length of the salt desired (octets)
@param key The private RSA key to use
@return CRYPT_OK if successful
*/
int rsa_sign_hash(const unsigned char *in, unsigned long inlen,
unsigned char *out, unsigned long *outlen,
prng_state *prng, int prng_idx,
int hash_idx, unsigned long saltlen,
rsa_key *key)
{
unsigned long modulus_bitlen, modulus_bytelen, x;
int err;
LTC_ARGCHK(in != NULL);
LTC_ARGCHK(out != NULL);
LTC_ARGCHK(outlen != NULL);
LTC_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 > *outlen) {
return CRYPT_BUFFER_OVERFLOW;
}
/* PSS pad the key */
x = *outlen;
if ((err = pkcs_1_pss_encode(in, inlen, saltlen, prng, prng_idx,
hash_idx, modulus_bitlen, out, &x)) != CRYPT_OK) {
return err;
}
/* RSA encode it */
return rsa_exptmod(out, x, out, outlen, PK_PRIVATE, key);
}
#endif /* MRSA */
/* $Source: /cvs/libtom/libtomcrypt/src/pk/rsa/rsa_sign_hash.c,v $ */
/* $Revision: 1.3 $ */
/* $Date: 2005/05/05 14:35:59 $ */
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