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#include "des.h"
#include "des_key.h"
#include "des_data.h"
#include "des_lookup.h"
#include <memory>
//#pragma GCC push_options
#ifndef _MSC_VER
#pragma GCC optimize ("unroll-loops")
#endif
DES::DES(ui64 key)
{
keygen(key);
}
DES::DES(ui64* sub_key)
{
set_sub_key(sub_key);
}
void DES::set_sub_key(ui64 *sub_key)
{
std::memcpy(this->sub_key, sub_key, 128);
}
ui64 DES::encrypt(ui64 block)
{
return des(block, false);
}
ui64 DES::decrypt(ui64 block)
{
return des(block, true);
}
ui64 DES::encrypt(ui64 block, ui64 key)
{
DES des(key);
return des.des(block, false);
}
ui64 DES::decrypt(ui64 block, ui64 key)
{
DES des(key);
return des.des(block, true);
}
void DES::keygen(ui64 key)
{
// initial key schedule calculation
ui64 permuted_choice_1 = 0; // 56 bits
for (ui8 i = 0; i < 56; i++)
{
permuted_choice_1 <<= 1;
permuted_choice_1 |= (key >> (64-PC1[i])) & LB64_MASK;
}
// 28 bits
ui32 C = (ui32) ((permuted_choice_1 >> 28) & 0x000000000fffffff);
ui32 D = (ui32) (permuted_choice_1 & 0x000000000fffffff);
// Calculation of the 16 keys
for (ui8 i = 0; i < 16; i++)
{
// key schedule, shifting Ci and Di
for (ui8 j = 0; j < ITERATION_SHIFT[i]; j++)
{
C = (0x0fffffff & (C << 1)) | (0x00000001 & (C >> 27));
D = (0x0fffffff & (D << 1)) | (0x00000001 & (D >> 27));
}
ui64 permuted_choice_2 = (((ui64) C) << 28) | (ui64) D;
sub_key[i] = 0; // 48 bits (2*24)
for (ui8 j = 0; j < 48; j++)
{
sub_key[i] <<= 1;
sub_key[i] |= (permuted_choice_2 >> (56-PC2[j])) & LB64_MASK;
}
}
}
ui64 DES::des(ui64 block, bool mode)
{
// applying initial permutation
block = ip(block);
// dividing T' into two 32-bit parts
ui32 L = (ui32) (block >> 32) & L64_MASK;
ui32 R = (ui32) (block & L64_MASK);
// 16 rounds
for (ui8 i = 0; i < 16; i++)
{
ui32 F = mode ? f(R, sub_key[15-i]) : f(R, sub_key[i]);
feistel(L, R, F);
}
// swapping the two parts
block = (((ui64) R) << 32) | (ui64) L;
// applying final permutation
return fp(block);
}
ui64 DES::ip(ui64 block)
{
// initial permutation
ui64 result = 0;
for (ui8 i = 0; i < 64; i++)
{
result <<= 1;
result |= (block >> (64-IP[i])) & LB64_MASK;
}
return result;
}
ui64 DES::fp(ui64 block)
{
// inverse initial permutation
ui64 result = 0;
for (ui8 i = 0; i < 64; i++)
{
result <<= 1;
result |= (block >> (64-FP[i])) & LB64_MASK;
}
return result;
}
void DES::feistel(ui32 &L, ui32 &R, ui32 F)
{
ui32 temp = R;
R = L ^ F;
L = temp;
}
ui32 DES::f(ui32 R, ui64 k) // f(R,k) function
{
// applying expansion permutation and returning 48-bit data
ui64 s_input = 0;
for (ui8 i = 0; i < 48; i++)
{
s_input <<= 1;
s_input |= (ui64) ((R >> (32-EXPANSION[i])) & LB32_MASK);
}
// XORing expanded Ri with Ki, the round key
s_input = s_input ^ k;
// applying S-Boxes function and returning 32-bit data
ui32 s_output = 0;
for (ui8 i = 0; i < 8; i++)
{
// Outer bits
char row = (char) ((s_input & (0x0000840000000000 >> 6*i)) >> (42-6*i));
row = (row >> 4) | (row & 0x01);
// Middle 4 bits of input
char column = (char) ((s_input & (0x0000780000000000 >> 6*i)) >> (43-6*i));
s_output <<= 4;
s_output |= (ui32) (SBOX[i][16*row + column] & 0x0f);
}
// applying the round permutation
ui32 f_result = 0;
for (ui8 i = 0; i < 32; i++)
{
f_result <<= 1;
f_result |= (s_output >> (32 - PBOX[i])) & LB32_MASK;
}
return f_result;
}
//#pragma GCC pop_options
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