blob: 7e9b3505ea6a671156cf550a39428500972236eb [file] [log] [blame]
/* 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_v15_sign_hash.c
RSA PKCS v1.5 Signature, Tom St Denis
*/
#ifdef MRSA
/**
PKCS #1 v1.5 pad then sign
@param in The hash to sign
@param inlen The length of the message hash (octets)
@param out [out] The signature
@param siglen [in/out] The max size and resulting size of the signature
@param hash_idx The index of the hash desired
@param key The private RSA key to perform the signature with
@return CRYPT_OK if successful
*/
int rsa_v15_sign_hash(const unsigned char *in, unsigned long inlen,
unsigned char *out, unsigned long *siglen,
int hash_idx, rsa_key *key)
{
unsigned long modulus_bitlen, modulus_bytelen, x;
int err;
LTC_ARGCHK(in != NULL);
LTC_ARGCHK(out != NULL);
LTC_ARGCHK(siglen != NULL);
LTC_ARGCHK(key != NULL);
/* valid hash ? */
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;
}
/* PKCS #1 v1.5 pad the key */
x = *siglen;
if ((err = pkcs_1_v15_sa_encode(in, inlen, hash_idx, modulus_bitlen, out, &x)) != CRYPT_OK) {
return err;
}
/* RSA encode it */
return rsa_exptmod(out, x, out, siglen, PK_PRIVATE, key);
}
#endif