mirror of
http://galexander.org/git/simplesshd.git
synced 2025-03-04 00:36:04 +00:00
116 lines
3.8 KiB
C
116 lines
3.8 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@gmail.com, http://libtomcrypt.com
|
|
*/
|
|
#include "tomcrypt.h"
|
|
|
|
/**
|
|
@file katja_exptmod.c
|
|
Katja PKCS-style exptmod, Tom St Denis
|
|
*/
|
|
|
|
#ifdef MKAT
|
|
|
|
/**
|
|
Compute an RSA modular exponentiation
|
|
@param in The input data to send into RSA
|
|
@param inlen The length of the input (octets)
|
|
@param out [out] The destination
|
|
@param outlen [in/out] The max size and resulting size of the output
|
|
@param which Which exponent to use, e.g. PK_PRIVATE or PK_PUBLIC
|
|
@param key The RSA key to use
|
|
@return CRYPT_OK if successful
|
|
*/
|
|
int katja_exptmod(const unsigned char *in, unsigned long inlen,
|
|
unsigned char *out, unsigned long *outlen, int which,
|
|
katja_key *key)
|
|
{
|
|
void *tmp, *tmpa, *tmpb;
|
|
unsigned long x;
|
|
int err;
|
|
|
|
LTC_ARGCHK(in != NULL);
|
|
LTC_ARGCHK(out != NULL);
|
|
LTC_ARGCHK(outlen != NULL);
|
|
LTC_ARGCHK(key != NULL);
|
|
|
|
/* is the key of the right type for the operation? */
|
|
if (which == PK_PRIVATE && (key->type != PK_PRIVATE)) {
|
|
return CRYPT_PK_NOT_PRIVATE;
|
|
}
|
|
|
|
/* must be a private or public operation */
|
|
if (which != PK_PRIVATE && which != PK_PUBLIC) {
|
|
return CRYPT_PK_INVALID_TYPE;
|
|
}
|
|
|
|
/* init and copy into tmp */
|
|
if ((err = mp_init_multi(&tmp, &tmpa, &tmpb, NULL)) != CRYPT_OK) { return err; }
|
|
if ((err = mp_read_unsigned_bin(tmp, (unsigned char *)in, (int)inlen)) != CRYPT_OK) { goto error; }
|
|
|
|
/* sanity check on the input */
|
|
if (mp_cmp(key->N, tmp) == LTC_MP_LT) {
|
|
err = CRYPT_PK_INVALID_SIZE;
|
|
goto done;
|
|
}
|
|
|
|
/* are we using the private exponent and is the key optimized? */
|
|
if (which == PK_PRIVATE) {
|
|
/* tmpa = tmp^dP mod p */
|
|
if ((err = mp_exptmod(tmp, key->dP, key->p, tmpa)) != CRYPT_OK) { goto error; }
|
|
|
|
/* tmpb = tmp^dQ mod q */
|
|
if ((err = mp_exptmod(tmp, key->dQ, key->q, tmpb)) != CRYPT_OK) { goto error; }
|
|
|
|
/* tmp = (tmpa - tmpb) * qInv (mod p) */
|
|
if ((err = mp_sub(tmpa, tmpb, tmp)) != CRYPT_OK) { goto error; }
|
|
if ((err = mp_mulmod(tmp, key->qP, key->p, tmp)) != CRYPT_OK) { goto error; }
|
|
|
|
/* tmp = tmpb + q * tmp */
|
|
if ((err = mp_mul(tmp, key->q, tmp)) != CRYPT_OK) { goto error; }
|
|
if ((err = mp_add(tmp, tmpb, tmp)) != CRYPT_OK) { goto error; }
|
|
} else {
|
|
/* exptmod it */
|
|
if ((err = mp_exptmod(tmp, key->N, key->N, tmp)) != CRYPT_OK) { goto error; }
|
|
}
|
|
|
|
/* read it back */
|
|
x = (unsigned long)mp_unsigned_bin_size(key->N);
|
|
if (x > *outlen) {
|
|
*outlen = x;
|
|
err = CRYPT_BUFFER_OVERFLOW;
|
|
goto done;
|
|
}
|
|
|
|
/* this should never happen ... */
|
|
if (mp_unsigned_bin_size(tmp) > mp_unsigned_bin_size(key->N)) {
|
|
err = CRYPT_ERROR;
|
|
goto done;
|
|
}
|
|
*outlen = x;
|
|
|
|
/* convert it */
|
|
zeromem(out, x);
|
|
if ((err = mp_to_unsigned_bin(tmp, out+(x-mp_unsigned_bin_size(tmp)))) != CRYPT_OK) { goto error; }
|
|
|
|
/* clean up and return */
|
|
err = CRYPT_OK;
|
|
goto done;
|
|
error:
|
|
done:
|
|
mp_clear_multi(tmp, tmpa, tmpb, NULL);
|
|
return err;
|
|
}
|
|
|
|
#endif
|
|
|
|
/* $Source: /cvs/libtom/libtomcrypt/src/pk/katja/katja_exptmod.c,v $ */
|
|
/* $Revision: 1.5 $ */
|
|
/* $Date: 2006/06/16 21:53:41 $ */
|