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Diffstat (limited to '')
| -rw-r--r-- | CryptoPP/twofish.cpp | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/CryptoPP/twofish.cpp b/CryptoPP/twofish.cpp new file mode 100644 index 000000000..064f16c44 --- /dev/null +++ b/CryptoPP/twofish.cpp @@ -0,0 +1,168 @@ +// 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 "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]; + case 3: x = Q(1, 1, 0, 0, x) ^ key[4]; + 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<word32> 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 = rotlFixed(h(i+1, key+1, len), 8); + m_k[i] = a+b; + m_k[i+1] = rotlFixed(a+2*b, 9); + } + + SecBlock<word32> svec(2*len); + for (i=0; i<len; i++) + svec[2*(len-i-1)] = ReedSolomon(key[2*i+1], key[2*i]); + for (i=0; i<256; i++) + { + word32 t = h0(i, svec, len); + m_s[0*256+i] = mds[0][GETBYTE(t, 0)]; + m_s[1*256+i] = mds[1][GETBYTE(t, 1)]; + m_s[2*256+i] = mds[2][GETBYTE(t, 2)]; + m_s[3*256+i] = mds[3][GETBYTE(t, 3)]; + } +} + +#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)]) +#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)]) + +#define ENCROUND(n, a, b, c, d) \ + x = G1 (a); y = G2 (b); \ + x += y; y += x + k[2 * (n) + 1]; \ + (c) ^= x + k[2 * (n)]; \ + (c) = rotrFixed(c, 1); \ + (d) = rotlFixed(d, 1) ^ 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) = rotrFixed(d, 1); \ + (c) = rotlFixed(c, 1); \ + (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<word32, LittleEndian> 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 |