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/*************************************************
* TEA Source File *
* (C) 1999-2006 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 = make_u32bit(in[0], in[1], in[2], in[3]),
right = make_u32bit(in[4], in[5], in[6], in[7]);
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]);
}
out[0] = get_byte(0, left); out[1] = get_byte(1, left);
out[2] = get_byte(2, left); out[3] = get_byte(3, left);
out[4] = get_byte(0, right); out[5] = get_byte(1, right);
out[6] = get_byte(2, right); out[7] = get_byte(3, right);
}
/*************************************************
* TEA Decryption *
*************************************************/
void TEA::dec(const byte in[], byte out[]) const
{
u32bit left = make_u32bit(in[0], in[1], in[2], in[3]),
right = make_u32bit(in[4], in[5], in[6], in[7]);
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;
}
out[0] = get_byte(0, left); out[1] = get_byte(1, left);
out[2] = get_byte(2, left); out[3] = get_byte(3, left);
out[4] = get_byte(0, right); out[5] = get_byte(1, right);
out[6] = get_byte(2, right); out[7] = get_byte(3, right);
}
/*************************************************
* TEA Key Schedule *
*************************************************/
void TEA::key(const byte key[], u32bit)
{
for(u32bit j = 0; j != 4; ++j)
K[j] = make_u32bit(key[4*j], key[4*j+1], key[4*j+2], key[4*j+3]);
}
}
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