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/*************************************************
* TEA Source File *
* (C) 1999-2007 The Botan Project *
*************************************************/
#include <botan/tea.h>
#include <botan/bit_ops.h>
namespace Botan {
/*************************************************
* TEA Encryption *
*************************************************/
void TEA::enc(const byte in[], byte out[]) const
{
u32bit left = load_be<u32bit>(in, 0), right = load_be<u32bit>(in, 1);
u32bit sum = 0;
for(u32bit j = 0; j != 32; ++j)
{
sum += 0x9E3779B9;
left += ((right << 4) + K[0]) ^ (right + sum) ^ ((right >> 5) + K[1]);
right += ((left << 4) + K[2]) ^ (left + sum) ^ ((left >> 5) + K[3]);
}
store_be(out, left, right);
}
/*************************************************
* TEA Decryption *
*************************************************/
void TEA::dec(const byte in[], byte out[]) const
{
u32bit left = load_be<u32bit>(in, 0), right = load_be<u32bit>(in, 1);
u32bit sum = 0xC6EF3720;
for(u32bit j = 0; j != 32; ++j)
{
right -= ((left << 4) + K[2]) ^ (left + sum) ^ ((left >> 5) + K[3]);
left -= ((right << 4) + K[0]) ^ (right + sum) ^ ((right >> 5) + K[1]);
sum -= 0x9E3779B9;
}
store_be(out, left, right);
}
/*************************************************
* TEA Key Schedule *
*************************************************/
void TEA::key(const byte key[], u32bit)
{
for(u32bit j = 0; j != 4; ++j)
K[j] = load_be<u32bit>(key, j);
}
}
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