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