square.cpp

// square.cpp - originally written and placed in the public domain by Wei Dai
// Based on Paulo S.L.M. Barreto's public domain implementation
 
#include "pch.h"
#include "config.h"
 
#include "square.h"
#include "misc.h"
#include "gf256.h"
 
#if CRYPTOPP_MSC_VERSION
# pragma warning(disable: 4244)
#endif
 
#if CRYPTOPP_GCC_DIAGNOSTIC_AVAILABLE
# pragma GCC diagnostic ignored "-Wmissing-braces"
#endif
 
NAMESPACE_BEGIN(CryptoPP)
 
// apply theta to a roundkey
static void SquareTransform (word32 in[4], word32 out[4])
{
    static const byte G[4][4] =
    {
        {0x02U, 0x01U, 0x01U, 0x03U},
        {0x03U, 0x02U, 0x01U, 0x01U},
        {0x01U, 0x03U, 0x02U, 0x01U},
        {0x01U, 0x01U, 0x03U, 0x02U}
    };
 
    GF256 gf256(0xf5);
 
    for (int i = 0; i < 4; i++)
    {
        word32 temp = 0;
        for (unsigned int j = 0; j < 4; j++)
            for (unsigned int k = 0; k < 4; k++)
                temp ^= (word32)gf256.Multiply(GETBYTE(in[i], 3-k), G[k][j]) << ((3-j)*8);
        out[i] = temp;
    }
}
 
#define roundkeys(i, j)     m_roundkeys[(i)*4+(j)]
#define roundkeys4(i)       (m_roundkeys+(i)*4)
 
void Square::Base::UncheckedSetKey(const byte *userKey, unsigned int length, const NameValuePairs &)
{
    AssertValidKeyLength(length);
 
    static const word32 offset[ROUNDS] = {
    0x01000000UL, 0x02000000UL, 0x04000000UL, 0x08000000UL,
    0x10000000UL, 0x20000000UL, 0x40000000UL, 0x80000000UL,
    };
 
    GetUserKey(BIG_ENDIAN_ORDER, m_roundkeys.data(), KEYLENGTH/4, userKey, KEYLENGTH);
 
    /* apply the key evolution function */
    for (int i = 1; i < ROUNDS+1; i++)
    {
        roundkeys(i, 0) = roundkeys(i-1, 0) ^ rotlConstant<8>(roundkeys(i-1, 3)) ^ offset[i-1];
        roundkeys(i, 1) = roundkeys(i-1, 1) ^ roundkeys(i, 0);
        roundkeys(i, 2) = roundkeys(i-1, 2) ^ roundkeys(i, 1);
        roundkeys(i, 3) = roundkeys(i-1, 3) ^ roundkeys(i, 2);
    }
 
    /* produce the round keys */
    if (IsForwardTransformation())
    {
        for (int i = 0; i < ROUNDS; i++)
            SquareTransform (roundkeys4(i), roundkeys4(i));
    }
    else
    {
        for (int i = 0; i < ROUNDS/2; i++)
            for (int j = 0; j < 4; j++)
                std::swap(roundkeys(i, j), roundkeys(ROUNDS-i, j));
        SquareTransform (roundkeys4(ROUNDS), roundkeys4(ROUNDS));
    }
}
 
#define MSB(x) (((x) >> 24) & 0xffU)    /* most  significant byte */
#define SSB(x) (((x) >> 16) & 0xffU)    /* second in significance */
#define TSB(x) (((x) >>  8) & 0xffU)    /* third  in significance */
#define LSB(x) (((x)      ) & 0xffU)    /* least significant byte */
 
#define squareRound(text, temp, T0, T1, T2, T3, roundkey) \
{ \
    temp[0] = T0[MSB (text[0])] \
            ^ T1[MSB (text[1])] \
            ^ T2[MSB (text[2])] \
            ^ T3[MSB (text[3])] \
            ^ roundkey[0]; \
    temp[1] = T0[SSB (text[0])] \
            ^ T1[SSB (text[1])] \
            ^ T2[SSB (text[2])] \
            ^ T3[SSB (text[3])] \
            ^ roundkey[1]; \
    temp[2] = T0[TSB (text[0])] \
            ^ T1[TSB (text[1])] \
            ^ T2[TSB (text[2])] \
            ^ T3[TSB (text[3])] \
            ^ roundkey[2]; \
    temp[3] = T0[LSB (text[0])] \
            ^ T1[LSB (text[1])] \
            ^ T2[LSB (text[2])] \
            ^ T3[LSB (text[3])] \
            ^ roundkey[3]; \
} /* squareRound */
 
#define squareFinal(text, temp, S, roundkey) \
{ \
    text[0] = ((word32) (S[MSB (temp[0])]) << 24) \
            ^ ((word32) (S[MSB (temp[1])]) << 16) \
            ^ ((word32) (S[MSB (temp[2])]) <<  8) \
            ^  (word32) (S[MSB (temp[3])]) \
            ^ roundkey[0]; \
    text[1] = ((word32) (S[SSB (temp[0])]) << 24) \
            ^ ((word32) (S[SSB (temp[1])]) << 16) \
            ^ ((word32) (S[SSB (temp[2])]) <<  8) \
            ^  (word32) (S[SSB (temp[3])]) \
            ^ roundkey[1]; \
    text[2] = ((word32) (S[TSB (temp[0])]) << 24) \
            ^ ((word32) (S[TSB (temp[1])]) << 16) \
            ^ ((word32) (S[TSB (temp[2])]) <<  8) \
            ^  (word32) (S[TSB (temp[3])]) \
            ^ roundkey[2]; \
    text[3] = ((word32) (S[LSB (temp[0])]) << 24) \
            ^ ((word32) (S[LSB (temp[1])]) << 16) \
            ^ ((word32) (S[LSB (temp[2])]) <<  8) \
            ^  (word32) (S[LSB (temp[3])]) \
            ^ roundkey[3]; \
} /* squareFinal */
 
typedef BlockGetAndPut<word32, BigEndian> Block;
 
void Square::Enc::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
    word32 text[4], temp[4];
    Block::Get(inBlock)(text[0])(text[1])(text[2])(text[3]);
 
    /* initial key addition */
    text[0] ^= roundkeys(0, 0);
    text[1] ^= roundkeys(0, 1);
    text[2] ^= roundkeys(0, 2);
    text[3] ^= roundkeys(0, 3);
 
    /* ROUNDS - 1 full rounds */
    for (int i=1; i+1<ROUNDS; i+=2)
    {
        squareRound (text, temp, Te[0], Te[1], Te[2], Te[3], roundkeys4(i));
        squareRound (temp, text, Te[0], Te[1], Te[2], Te[3], roundkeys4(i+1));
    }
    squareRound (text, temp, Te[0], Te[1], Te[2], Te[3], roundkeys4(ROUNDS-1));
 
    /* last round (diffusion becomes only transposition) */
    squareFinal (text, temp, Se, roundkeys4(ROUNDS));
 
    Block::Put(xorBlock, outBlock)(text[0])(text[1])(text[2])(text[3]);
}
 
void Square::Dec::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
    word32 text[4], temp[4];
    Block::Get(inBlock)(text[0])(text[1])(text[2])(text[3]);
 
    /* initial key addition */
    text[0] ^= roundkeys(0, 0);
    text[1] ^= roundkeys(0, 1);
    text[2] ^= roundkeys(0, 2);
    text[3] ^= roundkeys(0, 3);
 
    /* ROUNDS - 1 full rounds */
    for (int i=1; i+1<ROUNDS; i+=2)
    {
        squareRound (text, temp, Td[0], Td[1], Td[2], Td[3], roundkeys4(i));
        squareRound (temp, text, Td[0], Td[1], Td[2], Td[3], roundkeys4(i+1));
    }
    squareRound (text, temp, Td[0], Td[1], Td[2], Td[3], roundkeys4(ROUNDS-1));
 
    /* last round (diffusion becomes only transposition) */
    squareFinal (text, temp, Sd, roundkeys4(ROUNDS));
 
    Block::Put(xorBlock, outBlock)(text[0])(text[1])(text[2])(text[3]);
}
 
NAMESPACE_END