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/*
* Copyright (C) 1998,1999,2000,2001 Nikos Mavroyanopoulos
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Library General Public License as published
* by the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include <libdefs.h>
#include <mcrypt_modules.h>
#define _init_mcrypt ncfb_LTX__init_mcrypt
#define _mcrypt_set_state ncfb_LTX__mcrypt_set_state
#define _mcrypt_get_state ncfb_LTX__mcrypt_get_state
#define _end_mcrypt ncfb_LTX__end_mcrypt
#define _mcrypt ncfb_LTX__mcrypt
#define _mdecrypt ncfb_LTX__mdecrypt
#define _has_iv ncfb_LTX__has_iv
#define _is_block_mode ncfb_LTX__is_block_mode
#define _is_block_algorithm_mode ncfb_LTX__is_block_algorithm_mode
#define _mcrypt_get_modes_name ncfb_LTX__mcrypt_get_modes_name
#define _mcrypt_mode_get_size ncfb_LTX__mcrypt_mode_get_size
#define _mcrypt_mode_version ncfb_LTX__mcrypt_mode_version
typedef struct ncfb_buf {
byte* enc_s_register;
byte* s_register;
int s_register_pos;
int blocksize;
} nCFB_BUFFER;
/* nCFB MODE */
int _init_mcrypt( nCFB_BUFFER* buf, void *key, int lenofkey, void *IV, int size)
{
buf->enc_s_register = buf->s_register = NULL;
buf->s_register_pos = 0;
buf->blocksize = size;
/* For cfb */
buf->enc_s_register=malloc( size);
if (buf->enc_s_register==NULL) goto freeall;
buf->s_register=malloc( size);
if (buf->s_register==NULL) goto freeall;
if (IV!=NULL) {
memcpy(buf->enc_s_register, IV, size);
memcpy(buf->s_register, IV, size);
} else {
memset(buf->enc_s_register, 0, size);
memset(buf->s_register, 0, size);
}
/* End ncfb */
return 0;
freeall:
free(buf->enc_s_register);
free(buf->s_register);
return -1;
}
int _mcrypt_set_state( nCFB_BUFFER* buf, byte *IV, int size)
{
buf->s_register_pos = IV[0];
memcpy(buf->enc_s_register, &IV[1], size-1);
memcpy(buf->s_register, &IV[1], size-1);
return 0;
}
int _mcrypt_get_state( nCFB_BUFFER* buf, byte *IV, int *size)
{
if (*size < buf->blocksize + 1) {
*size = buf->blocksize + 1;
return -1;
}
*size = buf->blocksize + 1;
IV[0] = buf->s_register_pos;
memcpy( &IV[1], buf->s_register, buf->blocksize);
return 0;
}
void _end_mcrypt( nCFB_BUFFER* buf) {
free(buf->enc_s_register);
free(buf->s_register);
}
inline static
void xor_stuff_en( nCFB_BUFFER *buf, void* akey, void (*func)(void*,void*), byte* plain, int blocksize, int xor_size)
{
void (*_mcrypt_block_encrypt) (void *, void *);
_mcrypt_block_encrypt = func;
if (xor_size == blocksize) {
if (buf->s_register_pos == 0) {
memcpy(buf->enc_s_register, buf->s_register, blocksize);
_mcrypt_block_encrypt(akey, buf->enc_s_register);
memxor( plain, buf->enc_s_register, blocksize);
memcpy(buf->s_register, plain, blocksize);
} else {
int size = blocksize - buf->s_register_pos;
memxor( plain, &buf->enc_s_register[buf->s_register_pos],
size);
memcpy(buf->enc_s_register, buf->s_register, blocksize);
_mcrypt_block_encrypt(akey, buf->enc_s_register);
memxor( &plain[size], buf->enc_s_register,
buf->s_register_pos);
memcpy( &buf->s_register[size],
plain, buf->s_register_pos);
/* buf->s_register_pos remains the same */
}
} else { /* xor_size != blocksize */
if (buf->s_register_pos == 0) {
memcpy(buf->enc_s_register, buf->s_register, blocksize);
_mcrypt_block_encrypt(akey, buf->enc_s_register);
memxor( plain, buf->enc_s_register, xor_size);
memcpy(buf->s_register, plain, xor_size);
buf->s_register_pos = xor_size;
} else {
int size = blocksize - buf->s_register_pos;
int min_size = size < xor_size ? size: xor_size;
memxor( plain, &buf->enc_s_register[buf->s_register_pos],
min_size);
memcpy( &buf->s_register[buf->s_register_pos], plain, min_size);
buf->s_register_pos += min_size;
if (min_size >= xor_size)
return;
memcpy(buf->enc_s_register, buf->s_register, blocksize);
_mcrypt_block_encrypt(akey, buf->enc_s_register);
memxor( &plain[min_size], buf->s_register,
xor_size - min_size);
buf->s_register_pos = xor_size - min_size;
memcpy(buf->s_register, plain, xor_size - min_size);
}
}
return;
}
inline static
void xor_stuff_de( nCFB_BUFFER *buf, void* akey, void (*func)(void*,void*), byte* cipher, int blocksize, int xor_size)
{
void (*_mcrypt_block_encrypt) (void *, void *);
_mcrypt_block_encrypt = func;
if (xor_size == blocksize) {
if (buf->s_register_pos == 0) {
memcpy(buf->enc_s_register, buf->s_register, blocksize);
_mcrypt_block_encrypt(akey, buf->enc_s_register);
memcpy(buf->s_register, cipher, blocksize);
memxor( cipher, buf->enc_s_register, blocksize);
} else {
int size = blocksize - buf->s_register_pos;
memxor( cipher, &buf->enc_s_register[buf->s_register_pos],
size);
memcpy(buf->enc_s_register, buf->s_register, blocksize);
_mcrypt_block_encrypt(akey, buf->enc_s_register);
memcpy( &buf->s_register[size],
cipher, buf->s_register_pos);
memxor( &cipher[size], buf->enc_s_register,
buf->s_register_pos);
/* buf->s_register_pos remains the same */
}
} else { /* xor_size != blocksize */
if (buf->s_register_pos == 0) {
memcpy(buf->enc_s_register, buf->s_register, blocksize);
_mcrypt_block_encrypt(akey, buf->enc_s_register);
memcpy(buf->s_register, cipher, xor_size);
memxor( cipher, buf->enc_s_register, xor_size);
buf->s_register_pos = xor_size;
} else {
int size = blocksize - buf->s_register_pos;
int min_size = size < xor_size ? size: xor_size;
memxor( cipher, &buf->enc_s_register[buf->s_register_pos],
min_size);
memcpy( &buf->s_register[buf->s_register_pos], cipher, min_size);
buf->s_register_pos += min_size;
if (min_size >= xor_size)
return;
memcpy(buf->enc_s_register, buf->s_register, blocksize);
_mcrypt_block_encrypt(akey, buf->enc_s_register);
memcpy(buf->s_register, cipher, xor_size - min_size);
memxor( &cipher[min_size], buf->s_register,
xor_size - min_size);
buf->s_register_pos = xor_size - min_size;
}
}
return;
}
int _mcrypt( nCFB_BUFFER* buf,void *plaintext, int len, int blocksize, void* akey, void (*func)(void*,void*), void (*func2)(void*,void*))
{ /* plaintext is n*blocksize bytes (nbit cfb) */
byte* plain;
int i, j=0;
void (*_mcrypt_block_encrypt) (void *, void *);
int modlen;
_mcrypt_block_encrypt = func;
plain = plaintext;
for (j = 0; j < len / blocksize; j++) {
xor_stuff_en( buf, akey, func, plain, blocksize, blocksize);
plain += blocksize;
}
modlen = len % blocksize;
if (modlen > 0) {
xor_stuff_en( buf, akey, func, plain, blocksize, modlen);
}
return 0;
}
int _mdecrypt( nCFB_BUFFER* buf,void *plaintext, int len, int blocksize, void* akey, void (*func)(void*,void*), void (*func2)(void*,void*))
{ /* plaintext is n*blocksize bytes (nbit cfb) */
byte* plain;
int i, j=0;
void (*_mcrypt_block_encrypt) (void *, void *);
int modlen;
_mcrypt_block_encrypt = func;
plain = plaintext;
for (j = 0; j < len / blocksize; j++) {
xor_stuff_de( buf, akey, func, plain, blocksize, blocksize);
plain += blocksize;
}
modlen = len % blocksize;
if (modlen > 0) {
xor_stuff_de( buf, akey, func, plain, blocksize, modlen);
}
return 0;
}
int _has_iv() { return 1; }
int _is_block_mode() { return 0; }
int _is_block_algorithm_mode() { return 1; }
const char *_mcrypt_get_modes_name() { return "nCFB";}
int _mcrypt_mode_get_size () {return sizeof(nCFB_BUFFER);}
word32 _mcrypt_mode_version() {
return 20020307;
}
#ifdef WIN32
# ifdef USE_LTDL
WIN32DLL_DEFINE int main (void)
{
/* empty main function to avoid linker error (see cygwin FAQ) */
}
# endif
#endif
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