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/* 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://libtom.org
*/
#include "tomcrypt.h"
#include "ncr-int.h"
/**
@file rsa_decrypt_key.c
RSA LTC_PKCS #1 Decryption, Tom St Denis and Andreas Lange
*/
#ifdef LTC_MRSA
/**
LTC_PKCS #1 decrypt then v1.5 or OAEP depad
@param in The ciphertext
@param inlen The length of the ciphertext (octets)
@param out [out] The plaintext
@param outlen [in/out] The max size and resulting size of the plaintext (octets)
@param lparam The system "lparam" value
@param lparamlen The length of the lparam value (octets)
@param hash The desired hash
@param padding Type of padding (LTC_LTC_PKCS_1_OAEP or LTC_LTC_PKCS_1_V1_5)
@param stat [out] Result of the decryption, 1==valid, 0==invalid
@param key The corresponding private RSA key
@return CRYPT_OK if succcessul (even if invalid)
*/
int rsa_decrypt_key_ex(const unsigned char *in, unsigned long inlen,
unsigned char *out, unsigned long *outlen,
const unsigned char *lparam, unsigned long lparamlen,
const struct algo_properties_st *hash, int padding,
int *stat, rsa_key *key)
{
unsigned long modulus_bitlen, modulus_bytelen, x;
int err;
unsigned char *tmp;
LTC_ARGCHK(out != NULL);
LTC_ARGCHK(outlen != NULL);
LTC_ARGCHK(key != NULL);
LTC_ARGCHK(stat != NULL);
/* default to invalid */
*stat = 0;
/* valid padding? */
if ((padding != LTC_LTC_PKCS_1_V1_5) &&
(padding != LTC_LTC_PKCS_1_OAEP)) {
return CRYPT_PK_INVALID_PADDING;
}
if (padding == LTC_LTC_PKCS_1_OAEP) {
/* valid hash ? */
if ((err = hash_is_valid(hash)) != 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, key)) != CRYPT_OK) {
XFREE(tmp);
return err;
}
if (padding == LTC_LTC_PKCS_1_OAEP) {
/* now OAEP decode the packet */
err = pkcs_1_oaep_decode(tmp, x, lparam, lparamlen, modulus_bitlen, hash,
out, outlen, stat);
} else {
/* now LTC_PKCS #1 v1.5 depad the packet */
err = pkcs_1_v1_5_decode(tmp, x, LTC_LTC_PKCS_1_EME, modulus_bitlen, out, outlen, stat);
}
XFREE(tmp);
return err;
}
#endif /* LTC_MRSA */
/* $Source: /cvs/libtom/libtomcrypt/src/pk/rsa/rsa_decrypt_key.c,v $ */
/* $Revision: 1.10 $ */
/* $Date: 2007/05/12 14:32:35 $ */
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