void RC6Encryption::ProcessBlock(const byte *in, byte *out) const
{
const RC6_WORD *sptr = sTable;
RC6_WORD a, b, c, d, t, u;
GetBlockLittleEndian(in, a, b, c, d);
b += sptr[0];
d += sptr[1];
sptr += 2;
for(unsigned i=0; i<r; i++)
{
t = rotlFixed(b*(2*b+1), 5);
u = rotlFixed(d*(2*d+1), 5);
a = rotlMod(a^t,u) + sptr[0];
c = rotlMod(c^u,t) + sptr[1];
t = a; a = b; b = c; c = d; d = t;
sptr += 2;
}
a += sptr[0];
c += sptr[1];
PutBlockLittleEndian(out, a, b, c, d);
}
void RC6::Enc::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
const RC6_WORD *sptr = sTable;
RC6_WORD a, b, c, d, t, u;
Block::Get(inBlock)(a)(b)(c)(d);
b += sptr[0];
d += sptr[1];
sptr += 2;
for(unsigned i=0; i<r; i++)
{
t = rotlFixed(b*(2*b+1), 5);
u = rotlFixed(d*(2*d+1), 5);
a = rotlMod(a^t,u) + sptr[0];
c = rotlMod(c^u,t) + sptr[1];
t = a; a = b; b = c; c = d; d = t;
sptr += 2;
}
a += sptr[0];
c += sptr[1];
Block::Put(xorBlock, outBlock)(a)(b)(c)(d);
}
RC6Base::RC6Base(const byte *k, unsigned int keylen, unsigned int rounds)
: r(rounds), sTable((2*r)+4)
{
assert(keylen == KeyLength(keylen));
static const RC6_WORD MAGIC_P = 0xb7e15163L; // magic constant P for wordsize
static const RC6_WORD MAGIC_Q = 0x9e3779b9L; // magic constant Q for wordsize
static const int U=sizeof(RC6_WORD);
const unsigned int c=(keylen-1)/U + 1;
SecBlock<RC6_WORD> l(c);
GetUserKeyLittleEndian(l.ptr, c, k, keylen);
sTable[0] = MAGIC_P;
for (unsigned j=1; j<sTable.size;j++)
sTable[j] = sTable[j-1] + MAGIC_Q;
RC6_WORD a=0, b=0;
const unsigned n = 3*STDMAX(sTable.size,c);
for (unsigned h=0; h < n; h++)
{
a = sTable[h % sTable.size] = rotlFixed((sTable[h % sTable.size] + a + b), 3);
b = l[h % c] = rotlMod((l[h % c] + a + b), (a+b));
}
}
void RC6::Base::UncheckedSetKey(CipherDir direction, const byte *k, unsigned int keylen, unsigned int rounds)
{
AssertValidKeyLength(keylen);
AssertValidRounds(rounds);
r = rounds;
sTable.New(2*(r+2));
static const RC6_WORD MAGIC_P = 0xb7e15163L; // magic constant P for wordsize
static const RC6_WORD MAGIC_Q = 0x9e3779b9L; // magic constant Q for wordsize
static const int U=sizeof(RC6_WORD);
const unsigned int c = STDMAX((keylen+U-1)/U, 1U); // RC6 paper says c=1 if keylen==0
SecBlock<RC6_WORD> l(c);
GetUserKey(LITTLE_ENDIAN_ORDER, l.begin(), c, k, keylen);
sTable[0] = MAGIC_P;
for (unsigned j=1; j<sTable.size();j++)
sTable[j] = sTable[j-1] + MAGIC_Q;
RC6_WORD a=0, b=0;
const unsigned n = 3*STDMAX((unsigned int)sTable.size(), c);
for (unsigned h=0; h < n; h++)
{
a = sTable[h % sTable.size()] = rotlFixed((sTable[h % sTable.size()] + a + b), 3);
b = l[h % c] = rotlMod((l[h % c] + a + b), (a+b));
}
}
void RC5::Base::UncheckedSetKey(const byte *k, unsigned int keylen, const NameValuePairs ¶ms)
{
AssertValidKeyLength(keylen);
r = GetRoundsAndThrowIfInvalid(params, this);
sTable.New(2*(r+1));
static const RC5_WORD MAGIC_P = 0xb7e15163L; // magic constant P for wordsize
static const RC5_WORD MAGIC_Q = 0x9e3779b9L; // magic constant Q for wordsize
static const int U=sizeof(RC5_WORD);
const unsigned int c = STDMAX((keylen+U-1)/U, 1U); // RC6 paper says c=1 if keylen==0
SecBlock<RC5_WORD> l(c);
GetUserKey(LITTLE_ENDIAN_ORDER, l.begin(), c, k, keylen);
sTable[0] = MAGIC_P;
for (unsigned j=1; j<sTable.size();j++)
sTable[j] = sTable[j-1] + MAGIC_Q;
RC5_WORD a=0, b=0;
const unsigned n = 3*STDMAX((unsigned int)sTable.size(), c);
for (unsigned h=0; h < n; h++)
{
a = sTable[h % sTable.size()] = rotlConstant<3>((sTable[h % sTable.size()] + a + b));
b = l[h % c] = rotlMod((l[h % c] + a + b), (a+b));
}
}
void RC5::Enc::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
const RC5_WORD *sptr = sTable;
RC5_WORD a, b;
Block::Get(inBlock)(a)(b);
a += sptr[0];
b += sptr[1];
sptr += 2;
for(unsigned i=0; i<r; i++)
{
a = rotlMod(a^b,b) + sptr[2*i+0];
b = rotlMod(a^b,a) + sptr[2*i+1];
}
Block::Put(xorBlock, outBlock)(a)(b);
}
void GOST::Base::PrecalculateSTable()
{
if (!sTableCalculated)
{
for (unsigned i = 0; i < 4; i++)
for (unsigned j = 0; j < 256; j++)
{
word32 temp = sBox[2*i][j%16] | (sBox[2*i+1][j/16] << 4);
sTable[i][j] = rotlMod(temp, 11+8*i);
}
sTableCalculated=true;
}
}
