## File: twofish.cpp

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libcrypto++ 8.2.0-2
 `123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171` ``````// twofish.cpp - modified by Wei Dai from Matthew Skala's twofish.c // The original code and all modifications are in the public domain. #include "pch.h" #include "twofish.h" #include "secblock.h" #include "misc.h" NAMESPACE_BEGIN(CryptoPP) // compute (c * x^4) mod (x^4 + (a + 1/a) * x^3 + a * x^2 + (a + 1/a) * x + 1) // over GF(256) static inline unsigned int Mod(unsigned int c) { static const unsigned int modulus = 0x14d; unsigned int c2 = (c<<1) ^ ((c & 0x80) ? modulus : 0); unsigned int c1 = c2 ^ (c>>1) ^ ((c & 1) ? (modulus>>1) : 0); return c | (c1 << 8) | (c2 << 16) | (c1 << 24); } // compute RS(12,8) code with the above polynomial as generator // this is equivalent to multiplying by the RS matrix static word32 ReedSolomon(word32 high, word32 low) { for (unsigned int i=0; i<8; i++) { high = Mod(high>>24) ^ (high<<8) ^ (low>>24); low <<= 8; } return high; } inline word32 Twofish::Base::h0(word32 x, const word32 *key, unsigned int kLen) { x = x | (x<<8) | (x<<16) | (x<<24); switch(kLen) { #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) case 4: x = Q(1, 0, 0, 1, x) ^ key[6]; // fall through case 3: x = Q(1, 1, 0, 0, x) ^ key[4]; // fall through case 2: x = Q(0, 1, 0, 1, x) ^ key[2]; x = Q(0, 0, 1, 1, x) ^ key[0]; } return x; } inline word32 Twofish::Base::h(word32 x, const word32 *key, unsigned int kLen) { x = h0(x, key, kLen); return mds[0][GETBYTE(x,0)] ^ mds[1][GETBYTE(x,1)] ^ mds[2][GETBYTE(x,2)] ^ mds[3][GETBYTE(x,3)]; } void Twofish::Base::UncheckedSetKey(const byte *userKey, unsigned int keylength, const NameValuePairs &) { AssertValidKeyLength(keylength); unsigned int len = (keylength <= 16 ? 2 : (keylength <= 24 ? 3 : 4)); SecBlock key(len*2); GetUserKey(LITTLE_ENDIAN_ORDER, key.begin(), len*2, userKey, keylength); unsigned int i; for (i=0; i<40; i+=2) { word32 a = h(i, key, len); word32 b = rotlConstant<8>(h(i + 1, key + 1, len)); m_k[i] = a+b; m_k[i + 1] = rotlConstant<9>(a + 2 * b); } SecBlock svec(2*len); for (i=0; i(c); \ (d) = rotlConstant<1>(d) ^ y #define ENCCYCLE(n) \ ENCROUND (2 * (n), a, b, c, d); \ ENCROUND (2 * (n) + 1, c, d, a, b) #define DECROUND(n, a, b, c, d) \ x = G1 (a); y = G2 (b); \ x += y; y += x; \ (d) ^= y + k[2 * (n) + 1]; \ (d) = rotrConstant<1>(d); \ (c) = rotlConstant<1>(c); \ (c) ^= (x + k[2 * (n)]) #define DECCYCLE(n) \ DECROUND (2 * (n) + 1, c, d, a, b); \ DECROUND (2 * (n), a, b, c, d) typedef BlockGetAndPut Block; void Twofish::Enc::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const { word32 x, y, a, b, c, d; Block::Get(inBlock)(a)(b)(c)(d); a ^= m_k[0]; b ^= m_k[1]; c ^= m_k[2]; d ^= m_k[3]; const word32 *k = m_k+8; ENCCYCLE (0); ENCCYCLE (1); ENCCYCLE (2); ENCCYCLE (3); ENCCYCLE (4); ENCCYCLE (5); ENCCYCLE (6); ENCCYCLE (7); c ^= m_k[4]; d ^= m_k[5]; a ^= m_k[6]; b ^= m_k[7]; Block::Put(xorBlock, outBlock)(c)(d)(a)(b); } void Twofish::Dec::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const { word32 x, y, a, b, c, d; Block::Get(inBlock)(c)(d)(a)(b); c ^= m_k[4]; d ^= m_k[5]; a ^= m_k[6]; b ^= m_k[7]; const word32 *k = m_k+8; DECCYCLE (7); DECCYCLE (6); DECCYCLE (5); DECCYCLE (4); DECCYCLE (3); DECCYCLE (2); DECCYCLE (1); DECCYCLE (0); a ^= m_k[0]; b ^= m_k[1]; c ^= m_k[2]; d ^= m_k[3]; Block::Put(xorBlock, outBlock)(a)(b)(c)(d); } NAMESPACE_END ``````