base
This commit is contained in:
biosvos
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/*
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* Copyright (C) 2002 Nikos Mavroyanopoulos
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*
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* This library is free software; you can redistribute it and/or modify it
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* under the terms of the GNU Library General Public License as published
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* by the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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#include <libdefs.h>
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#include <mcrypt_modules.h>
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#define _init_mcrypt ctr_LTX__init_mcrypt
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#define _mcrypt_set_state ctr_LTX__mcrypt_set_state
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#define _mcrypt_get_state ctr_LTX__mcrypt_get_state
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#define _end_mcrypt ctr_LTX__end_mcrypt
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#define _mcrypt ctr_LTX__mcrypt
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#define _mdecrypt ctr_LTX__mdecrypt
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#define _has_iv ctr_LTX__has_iv
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#define _is_block_mode ctr_LTX__is_block_mode
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#define _is_block_algorithm_mode ctr_LTX__is_block_algorithm_mode
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#define _mcrypt_get_modes_name ctr_LTX__mcrypt_get_modes_name
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#define _mcrypt_mode_get_size ctr_LTX__mcrypt_mode_get_size
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#define _mcrypt_mode_version ctr_LTX__mcrypt_mode_version
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typedef struct ctr_buf {
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byte* enc_counter;
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byte* c_counter;
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int c_counter_pos;
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int blocksize;
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} CTR_BUFFER;
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/* CTR MODE */
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/* This function will add one to the given number (as a byte string).
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* has been reached.
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*/
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static void increase_counter( byte *x, int x_size) {
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register int i, y=0;
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for (i=x_size-1;i>=0;i--) {
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y = 0;
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if ( x[i] == 0xff) {
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x[i] = 0;
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y = 1;
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} else x[i]++;
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if (y==0) break;
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}
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return;
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}
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/* size holds the size of the IV (counter in this mode).
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* This is the block size.
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*/
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int _init_mcrypt( CTR_BUFFER* buf, void *key, int lenofkey, void *IV, int size)
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{
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buf->c_counter = buf->enc_counter = NULL;
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/* For ctr */
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buf->c_counter_pos = 0;
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buf->blocksize = size;
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buf->c_counter=calloc( 1, size);
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if (buf->c_counter==NULL) goto freeall;
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buf->enc_counter=calloc( 1, size);
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if (buf->enc_counter==NULL) goto freeall;
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if (IV!=NULL) {
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memcpy(buf->enc_counter, IV, size);
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memcpy(buf->c_counter, IV, size);
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}
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/* End ctr */
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return 0;
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freeall:
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free(buf->c_counter);
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free(buf->enc_counter);
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return -1;
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}
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int _mcrypt_set_state( CTR_BUFFER* buf, byte *IV, int size)
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{
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buf->c_counter_pos = IV[0];
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memcpy(buf->c_counter, &IV[1], size-1);
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memcpy(buf->enc_counter, &IV[1], size-1);
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return 0;
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}
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int _mcrypt_get_state( CTR_BUFFER* buf, byte *IV, int *size)
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{
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if (*size < buf->blocksize + 1) {
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*size = buf->blocksize + 1;
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return -1;
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}
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*size = buf->blocksize + 1;
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IV[0] = buf->c_counter_pos;
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memcpy( &IV[1], buf->c_counter, buf->blocksize);
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return 0;
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}
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void _end_mcrypt( CTR_BUFFER* buf) {
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free(buf->c_counter);
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free(buf->enc_counter);
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}
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inline static
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void xor_stuff( CTR_BUFFER *buf, void* akey, void (*func)(void*,void*), byte* plain, int blocksize, int xor_size)
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{
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void (*_mcrypt_block_encrypt) (void *, void *);
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_mcrypt_block_encrypt = func;
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if (xor_size == blocksize) {
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if (buf->c_counter_pos == 0) {
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memcpy( buf->enc_counter, buf->c_counter, blocksize);
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_mcrypt_block_encrypt(akey, buf->enc_counter);
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memxor( plain, buf->enc_counter, blocksize);
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increase_counter( buf->c_counter, blocksize);
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} else {
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int size = blocksize - buf->c_counter_pos;
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memxor( plain, &buf->enc_counter[buf->c_counter_pos],
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size);
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increase_counter( buf->c_counter, blocksize);
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memcpy( buf->enc_counter, buf->c_counter, blocksize);
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_mcrypt_block_encrypt(akey, buf->enc_counter);
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memxor( &plain[size], buf->enc_counter,
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buf->c_counter_pos);
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/* buf->c_counter_pos remains the same */
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}
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} else { /* xor_size != blocksize */
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if (buf->c_counter_pos == 0) {
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memcpy( buf->enc_counter, buf->c_counter, blocksize);
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_mcrypt_block_encrypt(akey, buf->enc_counter);
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memxor( plain, buf->enc_counter, xor_size);
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buf->c_counter_pos = xor_size;
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} else {
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int size = blocksize - buf->c_counter_pos;
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int min_size = size < xor_size ? size: xor_size;
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memxor( plain, &buf->enc_counter[buf->c_counter_pos],
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min_size);
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buf->c_counter_pos += min_size;
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if (min_size >= xor_size)
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return;
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increase_counter( buf->c_counter, blocksize);
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memcpy( buf->enc_counter, buf->c_counter, blocksize);
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_mcrypt_block_encrypt(akey, buf->enc_counter);
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memxor( &plain[min_size], buf->enc_counter,
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xor_size - min_size);
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buf->c_counter_pos = xor_size - min_size;
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}
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}
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return;
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}
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int _mcrypt( CTR_BUFFER* buf,void *plaintext, int len, int blocksize, void* akey, void (*func)(void*,void*), void (*func2)(void*,void*))
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{ /* plaintext can be any size */
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byte *plain;
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word32 *fplain = plaintext;
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int i, j=0;
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int modlen;
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plain = plaintext;
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for (j = 0; j < len / blocksize; j++) {
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xor_stuff( buf, akey, func, plain, blocksize, blocksize);
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plain += blocksize;
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/* Put the new register */
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}
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modlen = len % blocksize;
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if (modlen > 0) {
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/* This is only usefull if encrypting the
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* final block. Otherwise you'll not be
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* able to decrypt it.
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*/
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xor_stuff( buf, akey, func, plain, blocksize, modlen);
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}
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return 0;
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}
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int _mdecrypt( CTR_BUFFER* buf,void *plaintext, int len, int blocksize, void* akey, void (*func)(void*,void*), void (*func2)(void*,void*))
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{ /* plaintext can be any size */
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return _mcrypt( buf, plaintext, len, blocksize, akey, func, func2);
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}
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int _has_iv() { return 1; }
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int _is_block_mode() { return 0; }
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int _is_block_algorithm_mode() { return 1; }
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const char *_mcrypt_get_modes_name() { return "CTR";}
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int _mcrypt_mode_get_size () {return sizeof(CTR_BUFFER);}
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word32 _mcrypt_mode_version() {
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return 20020307;
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}
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#ifdef WIN32
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# ifdef USE_LTDL
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WIN32DLL_DEFINE int main (void)
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{
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/* empty main function to avoid linker error (see cygwin FAQ) */
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}
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# endif
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#endif
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