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// serpent.cpp - originally written and placed in the public domain by Wei Dai
#include "pch.h"
#include "serpent.h"
#include "secblock.h"
#include "misc.h"
#include "serpentp.h"
NAMESPACE_BEGIN(CryptoPP)
void Serpent_KeySchedule(word32 *k, unsigned int rounds, const byte *userKey, size_t keylen)
{
FixedSizeSecBlock<word32, 8> k0;
GetUserKey(LITTLE_ENDIAN_ORDER, k0.begin(), 8, userKey, keylen);
if (keylen < 32)
k0[keylen/4] |= word32(1) << ((keylen%4)*8);
word32 t = k0[7];
unsigned int i;
for (i = 0; i < 8; ++i)
k[i] = k0[i] = t = rotlConstant<11>(k0[i] ^ k0[(i + 3) % 8] ^ k0[(i + 5) % 8] ^ t ^ 0x9e3779b9 ^ i);
for (i = 8; i < 4*(rounds+1); ++i)
k[i] = t = rotlConstant<11>(k[i-8] ^ k[i-5] ^ k[i-3] ^ t ^ 0x9e3779b9 ^ i);
k -= 20;
word32 a,b,c,d,e;
for (i=0; i<rounds/8; i++)
{
afterS2(LK); afterS2(S3); afterS3(SK);
afterS1(LK); afterS1(S2); afterS2(SK);
afterS0(LK); afterS0(S1); afterS1(SK);
beforeS0(LK); beforeS0(S0); afterS0(SK);
k += 8*4;
afterS6(LK); afterS6(S7); afterS7(SK);
afterS5(LK); afterS5(S6); afterS6(SK);
afterS4(LK); afterS4(S5); afterS5(SK);
afterS3(LK); afterS3(S4); afterS4(SK);
}
afterS2(LK); afterS2(S3); afterS3(SK);
}
void Serpent::Base::UncheckedSetKey(const byte *userKey, unsigned int keylen, const NameValuePairs &)
{
AssertValidKeyLength(keylen);
Serpent_KeySchedule(m_key, 32, userKey, keylen);
}
typedef BlockGetAndPut<word32, LittleEndian> Block;
void Serpent::Enc::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
word32 a, b, c, d, e;
Block::Get(inBlock)(a)(b)(c)(d);
const word32 *k = m_key;
unsigned int i=1;
do
{
beforeS0(KX); beforeS0(S0); afterS0(LT);
afterS0(KX); afterS0(S1); afterS1(LT);
afterS1(KX); afterS1(S2); afterS2(LT);
afterS2(KX); afterS2(S3); afterS3(LT);
afterS3(KX); afterS3(S4); afterS4(LT);
afterS4(KX); afterS4(S5); afterS5(LT);
afterS5(KX); afterS5(S6); afterS6(LT);
afterS6(KX); afterS6(S7);
if (i == 4)
break;
++i;
c = b;
b = e;
e = d;
d = a;
a = e;
k += 32;
beforeS0(LT);
}
while (true);
afterS7(KX);
Block::Put(xorBlock, outBlock)(d)(e)(b)(a);
}
void Serpent::Dec::ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
{
word32 a, b, c, d, e=0;
Block::Get(inBlock)(a)(b)(c)(d);
const word32 *k = m_key + 96;
unsigned int i=4;
beforeI7(KX);
goto start;
do
{
c = b;
b = d;
d = e;
k -= 32;
beforeI7(ILT);
start:
beforeI7(I7); afterI7(KX);
afterI7(ILT); afterI7(I6); afterI6(KX);
afterI6(ILT); afterI6(I5); afterI5(KX);
afterI5(ILT); afterI5(I4); afterI4(KX);
afterI4(ILT); afterI4(I3); afterI3(KX);
afterI3(ILT); afterI3(I2); afterI2(KX);
afterI2(ILT); afterI2(I1); afterI1(KX);
afterI1(ILT); afterI1(I0); afterI0(KX);
}
while (--i != 0);
Block::Put(xorBlock, outBlock)(a)(d)(b)(e);
}
NAMESPACE_END
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