tea.cpp

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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(const byte *userKey, unsigned int length, const NameValuePairs &params)
{
        AssertValidKeyLength(length);

        GetUserKey(BIG_ENDIAN_ORDER, m_k.begin(), 4, userKey, KEYLENGTH);
        m_limit = GetRoundsAndThrowIfInvalid(params, this) * 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(const byte *userKey, unsigned int length,  const NameValuePairs &params)
{
        AssertValidKeyLength(length);

        GetUserKey(BIG_ENDIAN_ORDER, m_k.begin(), 4, userKey, KEYLENGTH);
        m_limit = GetRoundsAndThrowIfInvalid(params, this) * DELTA;
}

void XTEA::Enc::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
        word32 y, z;
        Block::Get(inBlock)(y)(z);

#ifdef __SUNPRO_CC
        // workaround needed on Sun Studio 12u1 Sun C++ 5.10 SunOS_i386 128229-02 2009/09/21
        size_t sum = 0;
        while ((sum&0xffffffff) != m_limit)
#else
        word32 sum = 0;
        while (sum != m_limit)
#endif
        {
                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);

#ifdef __SUNPRO_CC
        // workaround needed on Sun Studio 12u1 Sun C++ 5.10 SunOS_i386 128229-02 2009/09/21
        size_t sum = m_limit;
        while ((sum&0xffffffff) != 0)
#else
        word32 sum = m_limit;
        while (sum != 0)
#endif
        {
                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
{
        CRYPTOPP_UNUSED(xorBlock);
        CRYPTOPP_ASSERT(IsAlignedOn(inBlock,GetAlignmentOf<word32>()));
        CRYPTOPP_ASSERT(IsAlignedOn(outBlock,GetAlignmentOf<word32>()));

        unsigned int n = m_blockSize / 4;
        word32 *v = (word32*)(void *)outBlock;
        ConditionalByteReverse(BIG_ENDIAN_ORDER, v, (const word32*)(void *)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
{
        CRYPTOPP_UNUSED(xorBlock);
        CRYPTOPP_ASSERT(IsAlignedOn(inBlock,GetAlignmentOf<word32>()));
        CRYPTOPP_ASSERT(IsAlignedOn(outBlock,GetAlignmentOf<word32>()));

        unsigned int n = m_blockSize / 4;
        word32 *v = (word32*)(void *)outBlock;
        ConditionalByteReverse(BIG_ENDIAN_ORDER, v, (const word32*)(void *)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