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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"

NAMESPACE_BEGIN(CryptoPP)

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 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);        \
}                                                                                       

static void GenerateRoundConstants(word32 strt, word32 *rtab, unsigned int rounds)
{
        for(unsigned i=0; i<=rounds; i++)
        {
                rtab[i] = strt;
                strt <<= 1;
                if (strt&0x10000) strt ^= 0x11011;
        }
}

ThreeWayEncryption::ThreeWayEncryption(const byte *uk, unsigned int keylength, unsigned int rounds)
        : rounds(rounds), rc(rounds+1)
{
        assert(keylength == 0 || keylength == KEYLENGTH);
        GenerateRoundConstants(START_E, rc, rounds);
        for (int i=0; i<3; i++)
                k[i] = (word32)uk[4*i+3] | ((word32)uk[4*i+2]<<8) | ((word32)uk[4*i+1]<<16) | ((word32)uk[4*i]<<24);
}

ThreeWayEncryption::~ThreeWayEncryption()
{
        k[0]=k[1]=k[2]=0;
}

void ThreeWayEncryption::ProcessBlock(const byte *in, byte * out) const
{
        word32 a0, a1, a2;

#ifdef IS_LITTLE_ENDIAN
        a0 = byteReverse(*(word32 *)in);
        a1 = byteReverse(*(word32 *)(in+4));
        a2 = byteReverse(*(word32 *)(in+8));
#else
        a0 = *(word32 *)in;
        a1 = *(word32 *)(in+4);
        a2 = *(word32 *)(in+8);
#endif

        for(unsigned i=0; i<rounds; i++)
        {
                a0 ^= k[0] ^ (rc[i]<<16);
                a1 ^= k[1];
                a2 ^= k[2] ^ rc[i];
                rho(a0, a1, a2);
        }
        a0 ^= k[0] ^ (rc[rounds]<<16);
        a1 ^= k[1];
        a2 ^= k[2] ^ rc[rounds];
        theta(a0, a1, a2);

#ifdef IS_LITTLE_ENDIAN
        *(word32 *)out = byteReverse(a0);
        *(word32 *)(out+4) = byteReverse(a1);
        *(word32 *)(out+8) = byteReverse(a2);
#else
        *(word32 *)out = a0;
        *(word32 *)(out+4) = a1;
        *(word32 *)(out+8) = a2;
#endif
}

ThreeWayDecryption::ThreeWayDecryption(const byte *uk, unsigned int keylength, unsigned int rounds)
        : rounds(rounds), rc(rounds+1)
{
        assert(keylength == 0 || keylength == KEYLENGTH);
        GenerateRoundConstants(START_D, rc, rounds);
        for (int i=0; i<3; i++)
                k[i] = (word32)uk[4*i+3] | ((word32)uk[4*i+2]<<8) | ((word32)uk[4*i+1]<<16) | ((word32)uk[4*i]<<24);
        theta(k[0], k[1], k[2]);
        mu(k[0], k[1], k[2]);
        k[0] = byteReverse(k[0]);
        k[1] = byteReverse(k[1]);
        k[2] = byteReverse(k[2]);
}

ThreeWayDecryption::~ThreeWayDecryption()
{
        k[0]=k[1]=k[2]=0;
}

void ThreeWayDecryption::ProcessBlock(const byte *in, byte * out) const
{
        word32 a0, a1, a2;

#ifndef IS_LITTLE_ENDIAN
        a0 = byteReverse(*(word32 *)in);
        a1 = byteReverse(*(word32 *)(in+4));
        a2 = byteReverse(*(word32 *)(in+8));
#else
        a0 = *(word32 *)in;
        a1 = *(word32 *)(in+4);
        a2 = *(word32 *)(in+8);
#endif

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

#ifndef IS_LITTLE_ENDIAN
        *(word32 *)out = byteReverse(a0);
        *(word32 *)(out+4) = byteReverse(a1);
        *(word32 *)(out+8) = byteReverse(a2);
#else
        *(word32 *)out = a0;
        *(word32 *)(out+4) = a1;
        *(word32 *)(out+8) = a2;
#endif
}

NAMESPACE_END

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