--- /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 rsa_exptmod.c
+ RSA PKCS exptmod, Tom St Denis
+ Added RSA blinding --nmav
+*/
+
+#ifdef LTC_MRSA
+
+/**
+ 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 rsa_exptmod(const unsigned char *in, unsigned long inlen,
+ unsigned char *out, unsigned long *outlen, int which,
+ rsa_key *key)
+{
+ void *tmp, *tmpa, *tmpb;
+ #ifdef LTC_RSA_BLINDING
+ void *rnd, *rndi /* inverse of rnd */;
+ #endif
+ unsigned long x;
+ int err, has_crt_parameters;
+
+ 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,
+#ifdef LTC_RSA_BLINDING
+ &rnd, &rndi,
+#endif /* LTC_RSA_BLINDING */
+ 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 error;
+ }
+
+ /* are we using the private exponent and is the key optimized? */
+ if (which == PK_PRIVATE) {
+ #ifdef LTC_RSA_BLINDING
+ /* do blinding */
+ err = mp_rand(rnd, mp_get_digit_count(key->N));
+ if (err != CRYPT_OK) {
+ goto error;
+ }
+
+ /* rndi = 1/rnd mod N */
+ err = mp_invmod(rnd, key->N, rndi);
+ if (err != CRYPT_OK) {
+ goto error;
+ }
+
+ /* rnd = rnd^e */
+ err = mp_exptmod( rnd, key->e, key->N, rnd);
+ if (err != CRYPT_OK) {
+ goto error;
+ }
+
+ /* tmp = tmp*rnd mod N */
+ err = mp_mulmod( tmp, rnd, key->N, tmp);
+ if (err != CRYPT_OK) {
+ goto error;
+ }
+ #endif /* LTC_RSA_BLINDING */
+
+ has_crt_parameters = (key->p != NULL) && (mp_get_digit_count(key->p) != 0) &&
+ (key->q != NULL) && (mp_get_digit_count(key->q) != 0) &&
+ (key->dP != NULL) && (mp_get_digit_count(key->dP) != 0) &&
+ (key->dQ != NULL) && (mp_get_digit_count(key->dQ) != 0) &&
+ (key->qP != NULL) && (mp_get_digit_count(key->qP) != 0);
+
+ if (!has_crt_parameters) {
+ /*
+ * In case CRT optimization parameters are not provided,
+ * the private key is directly used to exptmod it
+ */
+ if ((err = mp_exptmod(tmp, key->d, key->N, tmp)) != CRYPT_OK) { goto error; }
+ } else {
+ /* 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; }
+ }
+
+ #ifdef LTC_RSA_BLINDING
+ /* unblind */
+ err = mp_mulmod( tmp, rndi, key->N, tmp);
+ if (err != CRYPT_OK) {
+ goto error;
+ }
+ #endif
+
+ #ifdef LTC_RSA_CRT_HARDENING
+ if (has_crt_parameters) {
+ if ((err = mp_exptmod(tmp, key->e, key->N, tmpa)) != CRYPT_OK) { goto error; }
+ if ((err = mp_read_unsigned_bin(tmpb, (unsigned char *)in, (int)inlen)) != CRYPT_OK) { goto error; }
+ if (mp_cmp(tmpa, tmpb) != LTC_MP_EQ) { err = CRYPT_ERROR; goto error; }
+ }
+ #endif
+ } else {
+ /* exptmod it */
+ if ((err = mp_exptmod(tmp, key->e, 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 error;
+ }
+
+ /* this should never happen ... */
+ if (mp_unsigned_bin_size(tmp) > mp_unsigned_bin_size(key->N)) {
+ err = CRYPT_ERROR;
+ goto error;
+ }
+ *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;
+error:
+ mp_clear_multi(
+#ifdef LTC_RSA_BLINDING
+ rndi, rnd,
+#endif /* LTC_RSA_BLINDING */
+ tmpb, tmpa, tmp, NULL);
+ return err;
+}
+
+#endif
+
+/* ref: $Format:%D$ */
+/* git commit: $Format:%H$ */
+/* commit time: $Format:%ai$ */
projects / zpackage / blobdiff