tor-android/external/badvpn_dns/security/OTPCalculator.c

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2015-01-25 11:08:34 +00:00
/**
* @file OTPCalculator.c
* @author Ambroz Bizjak <ambrop7@gmail.com>
*
* @section LICENSE
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the author nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <limits.h>
#include <misc/balloc.h>
#include <security/OTPCalculator.h>
int OTPCalculator_Init (OTPCalculator *calc, int num_otps, int cipher)
{
ASSERT(num_otps >= 0)
ASSERT(BEncryption_cipher_valid(cipher))
// init arguments
calc->num_otps = num_otps;
calc->cipher = cipher;
// remember block size
calc->block_size = BEncryption_cipher_block_size(calc->cipher);
// calculate number of blocks
if (calc->num_otps > SIZE_MAX / sizeof(otp_t)) {
goto fail0;
}
calc->num_blocks = bdivide_up(calc->num_otps * sizeof(otp_t), calc->block_size);
// allocate buffer
if (!(calc->data = (otp_t *)BAllocArray(calc->num_blocks, calc->block_size))) {
goto fail0;
}
// init debug object
DebugObject_Init(&calc->d_obj);
return 1;
fail0:
return 0;
}
void OTPCalculator_Free (OTPCalculator *calc)
{
// free debug object
DebugObject_Free(&calc->d_obj);
// free buffer
BFree(calc->data);
}
otp_t * OTPCalculator_Generate (OTPCalculator *calc, uint8_t *key, uint8_t *iv, int shuffle)
{
ASSERT(shuffle == 0 || shuffle == 1)
// copy IV so it can be updated
uint8_t iv_work[BENCRYPTION_MAX_BLOCK_SIZE];
memcpy(iv_work, iv, calc->block_size);
// create zero block
uint8_t zero[BENCRYPTION_MAX_BLOCK_SIZE];
memset(zero, 0, calc->block_size);
// init encryptor
BEncryption encryptor;
BEncryption_Init(&encryptor, BENCRYPTION_MODE_ENCRYPT, calc->cipher, key);
// encrypt zero blocks
for (size_t i = 0; i < calc->num_blocks; i++) {
BEncryption_Encrypt(&encryptor, zero, (uint8_t *)calc->data + i * calc->block_size, calc->block_size, iv_work);
}
// free encryptor
BEncryption_Free(&encryptor);
// shuffle if requested
if (shuffle) {
int i = 0;
while (i < calc->num_otps) {
uint16_t ints[256];
BRandom_randomize((uint8_t *)ints, sizeof(ints));
for (int j = 0; j < 256 && i < calc->num_otps; j++) {
int newIndex = i + (ints[j] % (calc->num_otps - i));
otp_t temp = calc->data[i];
calc->data[i] = calc->data[newIndex];
calc->data[newIndex] = temp;
i++;
}
}
}
return calc->data;
}