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