3way.cpp

// 3way.cpp - modified by Wei Dai from Joan Daemen's 3way.c
// The original code and all modifications are in the public domain.

#include "pch.h"
#include "3way.h"
#include "misc.h"

NAMESPACE_BEGIN(CryptoPP)

#if defined(CRYPTOPP_DEBUG) && !defined(CRYPTOPP_DOXYGEN_PROCESSING)
void ThreeWay_TestInstantiations()
{
    ThreeWay::Encryption x1;
    ThreeWay::Decryption x2;
}
#endif

namespace
{
    const word32 START_E = 0x0b0b; // round constant of first encryption round
    const word32 START_D = 0xb1b1; // round constant of first decryption round
}

static inline word32 reverseBits(word32 a)
{
    a = ((a & 0xAAAAAAAA) >> 1) | ((a & 0x55555555) << 1);
    a = ((a & 0xCCCCCCCC) >> 2) | ((a & 0x33333333) << 2);
    return ((a & 0xF0F0F0F0) >> 4) | ((a & 0x0F0F0F0F) << 4);
}

#define mu(a0, a1, a2)              \
{                                   \
    a1 = reverseBits(a1);           \
    word32 t = reverseBits(a0);     \
    a0 = reverseBits(a2);           \
    a2 = t;                         \
}

#define pi_gamma_pi(a0, a1, a2)   \
{                                 \
    word32 b0, b2;                          \
    b2 = rotlConstant<1>(a2);               \
    b0 = rotlConstant<22>(a0);              \
    a0 = rotlConstant<1>(b0 ^ (a1|(~b2)));  \
    a2 = rotlConstant<22>(b2 ^ (b0|(~a1))); \
    a1 ^= (b2|(~b0));                       \
}

// thanks to Paulo Barreto for this optimized theta()
#define theta(a0, a1, a2)                                   \
{                                                           \
    word32 b0, b1, c;                                       \
    c = a0 ^ a1 ^ a2;                                       \
    c = rotlConstant<16>(c) ^ rotlConstant<8>(c);           \
    b0 = (a0 << 24) ^ (a2 >> 8) ^ (a1 << 8) ^ (a0 >> 24);   \
    b1 = (a1 << 24) ^ (a0 >> 8) ^ (a2 << 8) ^ (a1 >> 24);   \
    a0 ^= c ^ b0;                                           \
    a1 ^= c ^ b1;                                           \
    a2 ^= c ^ (b0 >> 16) ^ (b1 << 16);                      \
}

#define rho(a0, a1, a2)         \
{                               \
    theta(a0, a1, a2);          \
    pi_gamma_pi(a0, a1, a2);    \
}

void ThreeWay::Base::UncheckedSetKey(const byte *uk, unsigned int length, const NameValuePairs &params)
{
    AssertValidKeyLength(length);

    m_rounds = GetRoundsAndThrowIfInvalid(params, this);

    for (unsigned int i=0; i<3; i++)
        m_k[i] = (word32)uk[4*i+3] | ((word32)uk[4*i+2]<<8) | ((word32)uk[4*i+1]<<16) | ((word32)uk[4*i]<<24);

    if (!IsForwardTransformation())
    {
        theta(m_k[0], m_k[1], m_k[2]);
        mu(m_k[0], m_k[1], m_k[2]);
        m_k[0] = ByteReverse(m_k[0]);
        m_k[1] = ByteReverse(m_k[1]);
        m_k[2] = ByteReverse(m_k[2]);
    }
}

void ThreeWay::Enc::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
    typedef BlockGetAndPut<word32, BigEndian> Block;

    word32 a0, a1, a2;
    Block::Get(inBlock)(a0)(a1)(a2);

    word32 rc = START_E;

    for(unsigned i=0; i<m_rounds; i++)
    {
        a0 ^= m_k[0] ^ (rc<<16);
        a1 ^= m_k[1];
        a2 ^= m_k[2] ^ rc;
        rho(a0, a1, a2);

        rc <<= 1;
        if (rc&0x10000) rc ^= 0x11011;
    }
    a0 ^= m_k[0] ^ (rc<<16);
    a1 ^= m_k[1];
    a2 ^= m_k[2] ^ rc;
    theta(a0, a1, a2);

    Block::Put(xorBlock, outBlock)(a0)(a1)(a2);
}

void ThreeWay::Dec::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
    typedef BlockGetAndPut<word32, LittleEndian> Block;

    word32 a0, a1, a2;
    Block::Get(inBlock)(a0)(a1)(a2);

    word32 rc = START_D;

    mu(a0, a1, a2);
    for(unsigned i=0; i<m_rounds; i++)
    {
        a0 ^= m_k[0] ^ (rc<<16);
        a1 ^= m_k[1];
        a2 ^= m_k[2] ^ rc;
        rho(a0, a1, a2);

        rc <<= 1;
        if (rc&0x10000) rc ^= 0x11011;
    }
    a0 ^= m_k[0] ^ (rc<<16);
    a1 ^= m_k[1];
    a2 ^= m_k[2] ^ rc;
    theta(a0, a1, a2);
    mu(a0, a1, a2);

    Block::Put(xorBlock, outBlock)(a0)(a1)(a2);
}

NAMESPACE_END