72 lines
1.8 KiB
C
72 lines
1.8 KiB
C
/* 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
|
|
|
|
/* decrypt then OAEP depad */
|
|
int rsa_decrypt_key(const unsigned char *in, unsigned long inlen,
|
|
unsigned char *outkey, unsigned long *keylen,
|
|
const unsigned char *lparam, unsigned long lparamlen,
|
|
prng_state *prng, int prng_idx,
|
|
int hash_idx, int *res,
|
|
rsa_key *key)
|
|
{
|
|
unsigned long modulus_bitlen, modulus_bytelen, x;
|
|
int err;
|
|
unsigned char *tmp;
|
|
|
|
_ARGCHK(outkey != NULL);
|
|
_ARGCHK(keylen != NULL);
|
|
_ARGCHK(key != NULL);
|
|
_ARGCHK(res != 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 != inlen) {
|
|
return CRYPT_INVALID_PACKET;
|
|
}
|
|
|
|
/* allocate ram */
|
|
tmp = XMALLOC(inlen);
|
|
if (tmp == NULL) {
|
|
return CRYPT_MEM;
|
|
}
|
|
|
|
/* rsa decode the packet */
|
|
x = inlen;
|
|
if ((err = rsa_exptmod(in, inlen, tmp, &x, PK_PRIVATE, prng, prng_idx, key)) != CRYPT_OK) {
|
|
XFREE(tmp);
|
|
return err;
|
|
}
|
|
|
|
/* now OAEP decode the packet */
|
|
err = pkcs_1_oaep_decode(tmp, x, lparam, lparamlen, modulus_bitlen, hash_idx,
|
|
outkey, keylen, res);
|
|
XFREE(tmp);
|
|
return err;
|
|
}
|
|
|
|
#endif /* MRSA */
|
|
|
|
|
|
|
|
|