+++ /dev/null
-/* 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.
- */
-#include "tomcrypt.h"
-
-/**
- @file katja_exptmod.c
- Katja PKCS-style exptmod, Tom St Denis
-*/
-
-#ifdef LTC_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
-
-/* ref: $Format:%D$ */
-/* git commit: $Format:%H$ */
-/* commit time: $Format:%ai$ */