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/*
* TEA
* (C) 1999-2007 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#include <botan/tea.h>
#include <botan/loadstor.h>
namespace Botan {
/*
* TEA Encryption
*/
void TEA::encrypt_n(const byte in[], byte out[], size_t blocks) const
{
for(size_t i = 0; i != blocks; ++i)
{
u32bit L = load_be<u32bit>(in, 0);
u32bit R = load_be<u32bit>(in, 1);
u32bit S = 0;
for(size_t j = 0; j != 32; ++j)
{
S += 0x9E3779B9;
L += ((R << 4) + K[0]) ^ (R + S) ^ ((R >> 5) + K[1]);
R += ((L << 4) + K[2]) ^ (L + S) ^ ((L >> 5) + K[3]);
}
store_be(out, L, R);
in += BLOCK_SIZE;
out += BLOCK_SIZE;
}
}
/*
* TEA Decryption
*/
void TEA::decrypt_n(const byte in[], byte out[], size_t blocks) const
{
for(size_t i = 0; i != blocks; ++i)
{
u32bit L = load_be<u32bit>(in, 0);
u32bit R = load_be<u32bit>(in, 1);
u32bit S = 0xC6EF3720;
for(size_t j = 0; j != 32; ++j)
{
R -= ((L << 4) + K[2]) ^ (L + S) ^ ((L >> 5) + K[3]);
L -= ((R << 4) + K[0]) ^ (R + S) ^ ((R >> 5) + K[1]);
S -= 0x9E3779B9;
}
store_be(out, L, R);
in += BLOCK_SIZE;
out += BLOCK_SIZE;
}
}
/*
* TEA Key Schedule
*/
void TEA::key_schedule(const byte key[], size_t)
{
K.resize(4);
for(size_t i = 0; i != 4; ++i)
K[i] = load_be<u32bit>(key, i);
}
}
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