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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://libtomcrypt.com
*/
#include "tomcrypt.h"
/**
@file katja_encrypt_key.c
Katja PKCS-style OAEP encryption, Tom St Denis
*/
#ifdef MKAT
/**
(PKCS #1 v2.0) OAEP pad then encrypt
@param in The plaintext
@param inlen The length of the plaintext (octets)
@param out [out] The ciphertext
@param outlen [in/out] The max size and resulting size of the ciphertext
@param lparam The system "lparam" for the encryption
@param lparamlen The length of lparam (octets)
@param prng An active PRNG
@param prng_idx The index of the desired prng
@param hash_idx The index of the desired hash
@param key The Katja key to encrypt to
@return CRYPT_OK if successful
*/
int katja_encrypt_key(const unsigned char *in, unsigned long inlen,
unsigned char *out, unsigned long *outlen,
const unsigned char *lparam, unsigned long lparamlen,
prng_state *prng, int prng_idx, int hash_idx, katja_key *key)
{
unsigned long modulus_bitlen, modulus_bytelen, x;
int err;
LTC_ARGCHK(in != NULL);
LTC_ARGCHK(out != NULL);
LTC_ARGCHK(outlen != NULL);
LTC_ARGCHK(key != NULL);
/* valid prng and hash ? */
if ((err = prng_is_valid(prng_idx)) != CRYPT_OK) {
return err;
}
if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) {
return err;
}
/* get modulus len in bits */
modulus_bitlen = mp_count_bits((key->N));
/* payload is upto pq, so we know q is 1/3rd the size of N and therefore pq is 2/3th the size */
modulus_bitlen = ((modulus_bitlen << 1) / 3);
/* round down to next byte */
modulus_bitlen -= (modulus_bitlen & 7) + 8;
/* outlen must be at least the size of the modulus */
modulus_bytelen = mp_unsigned_bin_size((key->N));
if (modulus_bytelen > *outlen) {
*outlen = modulus_bytelen;
return CRYPT_BUFFER_OVERFLOW;
}
/* OAEP pad the key */
x = *outlen;
if ((err = pkcs_1_oaep_encode(in, inlen, lparam,
lparamlen, modulus_bitlen, prng, prng_idx, hash_idx,
out, &x)) != CRYPT_OK) {
return err;
}
/* Katja exptmod the OAEP pad */
return katja_exptmod(out, x, out, outlen, PK_PUBLIC, key);
}
#endif /* MRSA */
/* $Source: /cvs/libtom/libtomcrypt/src/pk/katja/katja_encrypt_key.c,v $ */
/* $Revision: 1.5 $ */
/* $Date: 2006/06/16 21:53:41 $ */
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