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// tea.cpp - modified by Wei Dai from code in the original paper
#include "pch.h"
#include "tea.h"
#include "misc.h"
NAMESPACE_BEGIN(CryptoPP)
const word32 TEA::Base::DELTA = 0x9e3779b9;
void TEA::Base::UncheckedSetKey(CipherDir direction, const byte *userKey, unsigned int length)
{
AssertValidKeyLength(length);
GetUserKey(BIG_ENDIAN_ORDER, k.begin(), 4, userKey, KEYLENGTH);
}
typedef BlockGetAndPut<word32, BigEndian> Block;
void TEA::Enc::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
word32 y, z;
Block::Get(inBlock)(y)(z);
word32 sum = 0;
for (int i=0; i<ROUNDS; i++)
{
sum += DELTA;
y += (z << 4) + k[0] ^ z + sum ^ (z >> 5) + k[1];
z += (y << 4) + k[2] ^ y + sum ^ (y >> 5) + k[3];
}
Block::Put(xorBlock, outBlock)(y)(z);
}
typedef BlockGetAndPut<word32, BigEndian> Block;
void TEA::Dec::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
word32 y, z;
Block::Get(inBlock)(y)(z);
word32 sum = DELTA << LOG_ROUNDS;
for (int i=0; i<ROUNDS; i++)
{
z -= (y << 4) + k[2] ^ y + sum ^ (y >> 5) + k[3];
y -= (z << 4) + k[0] ^ z + sum ^ (z >> 5) + k[1];
sum -= DELTA;
}
Block::Put(xorBlock, outBlock)(y)(z);
}
NAMESPACE_END
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