3way.cpp

// 3way.cpp - modifed 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)

void ThreeWay_TestInstantiations()
{
        ThreeWay::Encryption x1;
        ThreeWay::Decryption x2;
}

static const word32 START_E = 0x0b0b; // round constant of first encryption round
static const word32 START_D = 0xb1b1; // round constant of first decryption round
static const word32 RC_MODULUS = 0x11011;

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 = rotlFixed(a2, 1U);                         \
        b0 = rotlFixed(a0, 22U);                                \
        a0 = rotlFixed(b0 ^ (a1|(~b2)), 1U);    \
        a2 = rotlFixed(b2 ^ (b0|(~a1)), 22U);\
        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 = rotlFixed(c, 16U) ^ rotlFixed(c, 8U);                               \
        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(CipherDir dir, const byte *uk, unsigned int length, unsigned int r)
{
        AssertValidKeyLength(length);
        AssertValidRounds(r);

        m_rounds = r;

        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 (dir == DECRYPTION)
        {
                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

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