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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)
static const word32 DELTA = 0x9e3779b9;
typedef BlockGetAndPut<word32, BigEndian> Block;
void TEA::Base::UncheckedSetKey(CipherDir direction, const byte *userKey, unsigned int length, unsigned int rounds)
{
AssertValidKeyLength(length);
GetUserKey(BIG_ENDIAN_ORDER, m_k.begin(), 4, userKey, KEYLENGTH);
m_limit = rounds * DELTA;
}
void TEA::Enc::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
word32 y, z;
Block::Get(inBlock)(y)(z);
word32 sum = 0;
while (sum != m_limit)
{
sum += DELTA;
y += (z << 4) + m_k[0] ^ z + sum ^ (z >> 5) + m_k[1];
z += (y << 4) + m_k[2] ^ y + sum ^ (y >> 5) + m_k[3];
}
Block::Put(xorBlock, outBlock)(y)(z);
}
void TEA::Dec::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
word32 y, z;
Block::Get(inBlock)(y)(z);
word32 sum = m_limit;
while (sum != 0)
{
z -= (y << 4) + m_k[2] ^ y + sum ^ (y >> 5) + m_k[3];
y -= (z << 4) + m_k[0] ^ z + sum ^ (z >> 5) + m_k[1];
sum -= DELTA;
}
Block::Put(xorBlock, outBlock)(y)(z);
}
void XTEA::Base::UncheckedSetKey(CipherDir direction, const byte *userKey, unsigned int length, unsigned int rounds)
{
AssertValidKeyLength(length);
GetUserKey(BIG_ENDIAN_ORDER, m_k.begin(), 4, userKey, KEYLENGTH);
m_limit = rounds * DELTA;
}
void XTEA::Enc::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
word32 y, z;
Block::Get(inBlock)(y)(z);
word32 sum = 0;
while (sum != m_limit)
{
y += (z<<4 ^ z>>5) + z ^ sum + m_k[sum&3];
sum += DELTA;
z += (y<<4 ^ y>>5) + y ^ sum + m_k[sum>>11 & 3];
}
Block::Put(xorBlock, outBlock)(y)(z);
}
void XTEA::Dec::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
word32 y, z;
Block::Get(inBlock)(y)(z);
word32 sum = m_limit;
while (sum != 0)
{
z -= (y<<4 ^ y>>5) + y ^ sum + m_k[sum>>11 & 3];
sum -= DELTA;
y -= (z<<4 ^ z>>5) + z ^ sum + m_k[sum&3];
}
Block::Put(xorBlock, outBlock)(y)(z);
}
#define MX (z>>5^y<<2)+(y>>3^z<<4)^(sum^y)+(m_k[p&3^e]^z)
void BTEA::Enc::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
unsigned int n = m_blockSize / 4;
word32 *v = (word32*)outBlock;
ConditionalByteReverse(BIG_ENDIAN_ORDER, v, (const word32*)inBlock, m_blockSize);
word32 y = v[0], z = v[n-1], e;
word32 p, q = 6+52/n;
word32 sum = 0;
while (q-- > 0)
{
sum += DELTA;
e = sum>>2 & 3;
for (p = 0; p < n-1; p++)
{
y = v[p+1];
z = v[p] += MX;
}
y = v[0];
z = v[n-1] += MX;
}
ConditionalByteReverse(BIG_ENDIAN_ORDER, v, v, m_blockSize);
}
void BTEA::Dec::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
unsigned int n = m_blockSize / 4;
word32 *v = (word32*)outBlock;
ConditionalByteReverse(BIG_ENDIAN_ORDER, v, (const word32*)inBlock, m_blockSize);
word32 y = v[0], z = v[n-1], e;
word32 p, q = 6+52/n;
word32 sum = q * DELTA;
while (sum != 0)
{
e = sum>>2 & 3;
for (p = n-1; p > 0; p--)
{
z = v[p-1];
y = v[p] -= MX;
}
z = v[n-1];
y = v[0] -= MX;
sum -= DELTA;
}
ConditionalByteReverse(BIG_ENDIAN_ORDER, v, v, m_blockSize);
}
NAMESPACE_END
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