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/*
* XTEA
* (C) 1999-2009,2016 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/xtea.h>
#include <botan/loadstor.h>
namespace Botan {
/*
* XTEA Encryption
*/
void XTEA::encrypt_n(const byte in[], byte out[], size_t blocks) const
{
const u32bit* EK = &m_EK[0];
const size_t blocks4 = blocks / 4;
const size_t blocks_left = blocks % 4;
BOTAN_PARALLEL_FOR(size_t i = 0; i < blocks4; i++)
{
u32bit L0, R0, L1, R1, L2, R2, L3, R3;
load_be(in + 4*BLOCK_SIZE*i, L0, R0, L1, R1, L2, R2, L3, R3);
for(size_t r = 0; r != 32; ++r)
{
L0 += (((R0 << 4) ^ (R0 >> 5)) + R0) ^ EK[2*r];
L1 += (((R1 << 4) ^ (R1 >> 5)) + R1) ^ EK[2*r];
L2 += (((R2 << 4) ^ (R2 >> 5)) + R2) ^ EK[2*r];
L3 += (((R3 << 4) ^ (R3 >> 5)) + R3) ^ EK[2*r];
R0 += (((L0 << 4) ^ (L0 >> 5)) + L0) ^ EK[2*r+1];
R1 += (((L1 << 4) ^ (L1 >> 5)) + L1) ^ EK[2*r+1];
R2 += (((L2 << 4) ^ (L2 >> 5)) + L2) ^ EK[2*r+1];
R3 += (((L3 << 4) ^ (L3 >> 5)) + L3) ^ EK[2*r+1];
}
store_be(out + 4*BLOCK_SIZE*i, L0, R0, L1, R1, L2, R2, L3, R3);
}
BOTAN_PARALLEL_FOR(size_t i = 0; i < blocks_left; ++i)
{
u32bit L, R;
load_be(in + BLOCK_SIZE*(4*blocks4+i), L, R);
for(size_t r = 0; r != 32; ++r)
{
L += (((R << 4) ^ (R >> 5)) + R) ^ EK[2*r];
R += (((L << 4) ^ (L >> 5)) + L) ^ EK[2*r+1];
}
store_be(out + BLOCK_SIZE*(4*blocks4+i), L, R);
}
}
/*
* XTEA Decryption
*/
void XTEA::decrypt_n(const byte in[], byte out[], size_t blocks) const
{
const u32bit* EK = &m_EK[0];
const size_t blocks4 = blocks / 4;
const size_t blocks_left = blocks % 4;
BOTAN_PARALLEL_FOR(size_t i = 0; i < blocks4; i++)
{
u32bit L0, R0, L1, R1, L2, R2, L3, R3;
load_be(in + 4*BLOCK_SIZE*i, L0, R0, L1, R1, L2, R2, L3, R3);
for(size_t r = 0; r != 32; ++r)
{
R0 -= (((L0 << 4) ^ (L0 >> 5)) + L0) ^ EK[63 - 2*r];
R1 -= (((L1 << 4) ^ (L1 >> 5)) + L1) ^ EK[63 - 2*r];
R2 -= (((L2 << 4) ^ (L2 >> 5)) + L2) ^ EK[63 - 2*r];
R3 -= (((L3 << 4) ^ (L3 >> 5)) + L3) ^ EK[63 - 2*r];
L0 -= (((R0 << 4) ^ (R0 >> 5)) + R0) ^ EK[62 - 2*r];
L1 -= (((R1 << 4) ^ (R1 >> 5)) + R1) ^ EK[62 - 2*r];
L2 -= (((R2 << 4) ^ (R2 >> 5)) + R2) ^ EK[62 - 2*r];
L3 -= (((R3 << 4) ^ (R3 >> 5)) + R3) ^ EK[62 - 2*r];
}
store_be(out + 4*BLOCK_SIZE*i, L0, R0, L1, R1, L2, R2, L3, R3);
}
BOTAN_PARALLEL_FOR(size_t i = 0; i < blocks_left; ++i)
{
u32bit L, R;
load_be(in + BLOCK_SIZE*(4*blocks4+i), L, R);
for(size_t r = 0; r != 32; ++r)
{
R -= (((L << 4) ^ (L >> 5)) + L) ^ m_EK[63 - 2*r];
L -= (((R << 4) ^ (R >> 5)) + R) ^ m_EK[62 - 2*r];
}
store_be(out + BLOCK_SIZE*(4*blocks4+i), L, R);
}
}
/*
* XTEA Key Schedule
*/
void XTEA::key_schedule(const byte key[], size_t)
{
m_EK.resize(64);
secure_vector<u32bit> UK(4);
for(size_t i = 0; i != 4; ++i)
UK[i] = load_be<u32bit>(key, i);
u32bit D = 0;
for(size_t i = 0; i != 64; i += 2)
{
m_EK[i ] = D + UK[D % 4];
D += 0x9E3779B9;
m_EK[i+1] = D + UK[(D >> 11) % 4];
}
}
void XTEA::clear()
{
zap(m_EK);
}
}
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