tea.cpp

// tea.cpp - modified by Wei Dai from code in the original paper
 
#include "pch.h"
#include "tea.h"
#include "misc.h"
 
// http://github.com/weidai11/cryptopp/issues/503
#if defined(__xlC__) || defined(__SUNPRO_CC)
# define MAYBE_VOLATILE(x) (*const_cast<volatile word32*>(&x))
#else
# define MAYBE_VOLATILE(x) (x)
#endif
 
NAMESPACE_BEGIN(CryptoPP)
 
static const word32 DELTA = 0x9e3779b9;
typedef BlockGetAndPut<word32, BigEndian> Block;
 
#define UINT32_CAST(x) ((word32*)(void*)(x))
#define CONST_UINT32_CAST(x) ((const word32*)(const void*)(x))
 
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, sum = 0;
        Block::Get(inBlock)(y)(z);
 
        // http://github.com/weidai11/cryptopp/issues/503
        while (MAYBE_VOLATILE(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, sum = m_limit;
        Block::Get(inBlock)(y)(z);
 
        // http://github.com/weidai11/cryptopp/issues/503
        while (MAYBE_VOLATILE(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, sum = 0;
        Block::Get(inBlock)(y)(z);
 
        // http://github.com/weidai11/cryptopp/issues/503
        while (MAYBE_VOLATILE(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, sum = m_limit;
        Block::Get(inBlock)(y)(z);
 
        // http://github.com/weidai11/cryptopp/issues/503
        while (MAYBE_VOLATILE(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
{
        CRYPTOPP_UNUSED(xorBlock);
        CRYPTOPP_ASSERT(IsAlignedOn(inBlock,GetAlignmentOf<word32>()));
        CRYPTOPP_ASSERT(IsAlignedOn(outBlock,GetAlignmentOf<word32>()));
 
        unsigned int n = m_blockSize / 4;
        word32 *v = UINT32_CAST(outBlock);
        ConditionalByteReverse(BIG_ENDIAN_ORDER, v, CONST_UINT32_CAST(inBlock), m_blockSize);
 
        word32 y, 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 = UINT32_CAST(outBlock);
        ConditionalByteReverse(BIG_ENDIAN_ORDER, v, CONST_UINT32_CAST(inBlock), m_blockSize);
 
        word32 y = v[0], z, 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