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169 lines
4.1 KiB
169 lines
4.1 KiB
![]()
4 years ago
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// twofish.cpp - modified by Wei Dai from Matthew Skala's twofish.c
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// The original code and all modifications are in the public domain.
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#include "pch.h"
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#include "twofish.h"
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#include "misc.h"
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NAMESPACE_BEGIN(CryptoPP)
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// compute (c * x^4) mod (x^4 + (a + 1/a) * x^3 + a * x^2 + (a + 1/a) * x + 1)
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// over GF(256)
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static inline unsigned int Mod(unsigned int c)
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{
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static const unsigned int modulus = 0x14d;
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unsigned int c2 = (c<<1) ^ ((c & 0x80) ? modulus : 0);
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unsigned int c1 = c2 ^ (c>>1) ^ ((c & 1) ? (modulus>>1) : 0);
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return c | (c1 << 8) | (c2 << 16) | (c1 << 24);
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}
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// compute RS(12,8) code with the above polynomial as generator
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// this is equivalent to multiplying by the RS matrix
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static word32 ReedSolomon(word32 high, word32 low)
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{
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for (unsigned int i=0; i<8; i++)
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{
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high = Mod(high>>24) ^ (high<<8) ^ (low>>24);
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low <<= 8;
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}
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return high;
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}
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inline word32 Twofish::Base::h0(word32 x, const word32 *key, unsigned int kLen)
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{
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x = x | (x<<8) | (x<<16) | (x<<24);
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switch(kLen)
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{
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#define Q(a, b, c, d, t) q[a][GETBYTE(t,0)] ^ (q[b][GETBYTE(t,1)] << 8) ^ (q[c][GETBYTE(t,2)] << 16) ^ (q[d][GETBYTE(t,3)] << 24)
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case 4: x = Q(1, 0, 0, 1, x) ^ key[6];
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case 3: x = Q(1, 1, 0, 0, x) ^ key[4];
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case 2: x = Q(0, 1, 0, 1, x) ^ key[2];
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x = Q(0, 0, 1, 1, x) ^ key[0];
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}
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return x;
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}
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inline word32 Twofish::Base::h(word32 x, const word32 *key, unsigned int kLen)
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{
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x = h0(x, key, kLen);
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return mds[0][GETBYTE(x,0)] ^ mds[1][GETBYTE(x,1)] ^ mds[2][GETBYTE(x,2)] ^ mds[3][GETBYTE(x,3)];
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}
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void Twofish::Base::UncheckedSetKey(const byte *userKey, unsigned int keylength, const NameValuePairs &)
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{
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AssertValidKeyLength(keylength);
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unsigned int len = (keylength <= 16 ? 2 : (keylength <= 24 ? 3 : 4));
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SecBlock<word32> key(len*2);
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GetUserKey(LITTLE_ENDIAN_ORDER, key.begin(), len*2, userKey, keylength);
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unsigned int i;
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for (i=0; i<40; i+=2)
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{
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word32 a = h(i, key, len);
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word32 b = rotlFixed(h(i+1, key+1, len), 8);
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m_k[i] = a+b;
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m_k[i+1] = rotlFixed(a+2*b, 9);
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}
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SecBlock<word32> svec(2*len);
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for (i=0; i<len; i++)
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svec[2*(len-i-1)] = ReedSolomon(key[2*i+1], key[2*i]);
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for (i=0; i<256; i++)
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{
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word32 t = h0(i, svec, len);
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m_s[0*256+i] = mds[0][GETBYTE(t, 0)];
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m_s[1*256+i] = mds[1][GETBYTE(t, 1)];
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m_s[2*256+i] = mds[2][GETBYTE(t, 2)];
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m_s[3*256+i] = mds[3][GETBYTE(t, 3)];
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}
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}
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#define G1(x) (m_s[0*256+GETBYTE(x,0)] ^ m_s[1*256+GETBYTE(x,1)] ^ m_s[2*256+GETBYTE(x,2)] ^ m_s[3*256+GETBYTE(x,3)])
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#define G2(x) (m_s[0*256+GETBYTE(x,3)] ^ m_s[1*256+GETBYTE(x,0)] ^ m_s[2*256+GETBYTE(x,1)] ^ m_s[3*256+GETBYTE(x,2)])
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#define ENCROUND(n, a, b, c, d) \
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x = G1 (a); y = G2 (b); \
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x += y; y += x + k[2 * (n) + 1]; \
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(c) ^= x + k[2 * (n)]; \
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(c) = rotrFixed(c, 1); \
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(d) = rotlFixed(d, 1) ^ y
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#define ENCCYCLE(n) \
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ENCROUND (2 * (n), a, b, c, d); \
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ENCROUND (2 * (n) + 1, c, d, a, b)
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#define DECROUND(n, a, b, c, d) \
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x = G1 (a); y = G2 (b); \
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x += y; y += x; \
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(d) ^= y + k[2 * (n) + 1]; \
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(d) = rotrFixed(d, 1); \
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(c) = rotlFixed(c, 1); \
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(c) ^= (x + k[2 * (n)])
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#define DECCYCLE(n) \
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DECROUND (2 * (n) + 1, c, d, a, b); \
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DECROUND (2 * (n), a, b, c, d)
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typedef BlockGetAndPut<word32, LittleEndian> Block;
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void Twofish::Enc::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
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{
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word32 x, y, a, b, c, d;
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Block::Get(inBlock)(a)(b)(c)(d);
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a ^= m_k[0];
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b ^= m_k[1];
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c ^= m_k[2];
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d ^= m_k[3];
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const word32 *k = m_k+8;
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ENCCYCLE (0);
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ENCCYCLE (1);
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ENCCYCLE (2);
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ENCCYCLE (3);
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ENCCYCLE (4);
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ENCCYCLE (5);
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ENCCYCLE (6);
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ENCCYCLE (7);
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c ^= m_k[4];
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d ^= m_k[5];
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a ^= m_k[6];
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b ^= m_k[7];
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Block::Put(xorBlock, outBlock)(c)(d)(a)(b);
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}
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void Twofish::Dec::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
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{
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word32 x, y, a, b, c, d;
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Block::Get(inBlock)(c)(d)(a)(b);
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c ^= m_k[4];
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d ^= m_k[5];
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a ^= m_k[6];
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b ^= m_k[7];
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const word32 *k = m_k+8;
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DECCYCLE (7);
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DECCYCLE (6);
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DECCYCLE (5);
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DECCYCLE (4);
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DECCYCLE (3);
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DECCYCLE (2);
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DECCYCLE (1);
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DECCYCLE (0);
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a ^= m_k[0];
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b ^= m_k[1];
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c ^= m_k[2];
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d ^= m_k[3];
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Block::Put(xorBlock, outBlock)(a)(b)(c)(d);
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}
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NAMESPACE_END
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