DES 加密算法的實作

概述

DES加密算法，算是密碼學裡入門的知識了，前段時間有興趣搞了一下，但是沒有做完。現在桌面實在是東西太多了，暫且丢到部落格裡，以後有空再來改一下。

一共三個檔案：

data.h 各種表組成的頭檔案
des.h DES加密算法的主要函數都在裡邊了
test.cpp 測試各個函數的測試檔案

貼代碼：

/*
 	下面是DES加密算法的各種置換表
 	由Halfish整理，2014.12.13
 */


//初始置換表IP
int IP_Table[64] = {  
	57,49,41,33,25,17,9,1,
	59,51,43,35,27,19,11,3,
	61,53,45,37,29,21,13,5,
	63,55,47,39,31,23,15,7,
	56,48,40,32,24,16,8,0,
	58,50,42,34,26,18,10,2,
	60,52,44,36,28,20,12,4,
	62,54,46,38,30,22,14,6
}; 

//逆初始置換表IP^-1
int IP_1_Table[64] = {
	39,7,47,15,55,23,63,31,
	38,6,46,14,54,22,62,30,
	37,5,45,13,53,21,61,29,
	36,4,44,12,52,20,60,28,
	35,3,43,11,51,19,59,27,
	34,2,42,10,50,18,58,26,
	33,1,41,9,49,17,57,25,
	32,0,40,8,48,16,56,24 
};

//擴充置換表E
int E_Table[48] = {
	31, 0, 1, 2, 3, 4,
	 3, 4, 5, 6, 7, 8,
	 7, 8, 9,10,11,12,
	11,12,13,14,15,16,
	15,16,17,18,19,20,
	19,20,21,22,23,24,
	23,24,25,26,27,28,
	27,28,29,30,31, 0 
};



//置換選擇1
int PC_1[56] = {
	56,48,40,32,24,16,8,
	0,57,49,41,33,25,17,
	9,1,58,50,42,34,26,
	18,10,2,59,51,43,35,
	62,54,46,38,30,22,14,
	6,61,53,45,37,29,21,
	13,5,60,52,44,36,28,
	20,12,4,27,19,11,3
};

//置換選擇2, 又叫做壓縮置換
int PC_2[48] = {
	13,16,10,23,0,4,2,27,
	14,5,20,9,22,18,11,3,
	25,7,15,6,26,19,12,1,
	40,51,30,36,46,54,29,39,
	50,44,32,46,43,48,38,55,
	33,52,45,41,49,35,28,31
};

//對左移次數的規定
int left_move_times[16] = {
	1,1,2,2, 2,2,2,2, 
	1,2,2,2, 2,2,2,1
};

//置換函數P
int P_Table[32] = {
	15, 6,19,20,28,11,27,16,
	 0,14,22,25, 4,17,30, 9,
	 1, 7,23,13,31,26, 2, 8,
	18,12,29, 5,21,10, 3,24 
};

//S盒
int S[8][64] =
			{
				//S1
				{
					14,4,13,1,2,15,11,8,3,10,6,12,5,9,0,7,
					0,15,7,4,14,2,13,1,10,6,12,11,9,5,3,8,
					4,1,14,8,13,6,2,11,15,12,9,7,3,10,5,0,
					15,12,8,2,4,9,1,7,5,11,3,14,10,0,6,13
				},

				//S2
				{
					15,1,8,14,6,11,3,4,9,7,2,13,12,0,5,10,
					3,13,4,7,15,2,8,14,12,0,1,10,6,9,11,5,
					0,14,7,11,10,4,13,1,5,8,12,6,9,3,2,15,
					13,8,10,1,3,15,4,2,11,6,7,12,0,5,14,9
				},

				//S3
				{
					10,0,9,14,6,3,15,5,1,13,12,7,11,4,2,8,
					13,7,0,9,3,4,6,10,2,8,5,14,12,11,15,1,
					13,6,4,9,8,15,3,0,11,1,2,12,5,10,14,7,
					1,10,13,0,6,9,8,7,4,15,14,3,11,5,2,12
				},

				//S4
				{
					7,13,14,3,0,6,9,10,1,2,8,5,11,12,4,15,
					13,8,11,5,6,15,0,3,4,7,2,12,1,10,14,9,
					10,6,9,0,12,11,7,13,15,1,3,14,5,2,8,4,
					3,15,0,6,10,1,13,8,9,4,5,11,12,7,2,14
				},

				//S5
				{
					2,12,4,1,7,10,11,6,8,5,3,15,13,0,14,9,
					14,11,2,12,4,7,13,1,5,0,15,10,3,9,8,6,
					4,2,1,11,10,13,7,8,15,9,12,5,6,3,0,14,
					11,8,12,7,1,14,2,13,6,15,0,9,10,4,5,3
				},

				//S6
				{
					12,1,10,15,9,2,6,8,0,13,3,4,14,7,5,11,
					10,15,4,2,7,12,9,5,6,1,13,14,0,11,3,8,
					9,14,15,5,2,8,12,3,7,0,4,10,1,13,11,6,
					4,3,2,12,9,5,15,10,11,14,1,7,6,0,8,13
				},

				//S7
				{
					4,11,2,14,15,0,8,13,3,12,9,7,5,10,6,1,
					13,0,11,7,4,9,1,10,14,3,5,12,2,15,8,6,
					1,4,11,13,12,3,7,14,10,15,6,8,0,5,9,2,
					6,11,13,8,1,4,10,7,9,5,0,15,14,2,3,12
				},

				//S8
				{
					13,2,8,4,6,15,11,1,10,9,3,14,5,0,12,7,
					1,15,13,8,10,3,7,4,12,5,6,11,0,14,9,2,
					7,11,4,1,9,12,14,2,0,6,10,13,15,3,5,8,
					2,1,14,7,4,10,8,13,15,12,9,0,3,5,6,11
				}
			};

des.h

/*
 * Halfish 
 * 2014 December
 */

#include <iostream>
#include <cstdio>
#include <cstring>
#include "data.h"
using namespace std;

const int EXTRA_BITS = 1;

void mstrcpy(char to[], char from[], int offset) {
	for (int i = 0; i < offset; ++i)
	{
		to[i] = from[i];
	}
}

// 初始置換
void initial_permutation(char plain_block[]) 
{
	char temp[64 + EXTRA_BITS];
	mstrcpy(temp, plain_block, 64);

	for (int i = 0; i < 64; ++ i) {
		plain_block[i] = temp[IP_Table[i]];	
	}
}

// 置換選擇1: subkey[56] <-- key[64]
void get_subkey(char subkey[], const char key[]) 
{
	for (int i = 0; i < 56; ++ i)
	{
		subkey[i] = key[PC_1[i]];
	}
}

void shift_subkey(int shift, char subkey[], int size)
{
	char temp0 = subkey[0];
	char temp1 = subkey[1];
	
	switch(shift) {
		case 1:
			for (int i = 0; i < size - 1; ++ i) {
				subkey[i] = subkey[i + 1];
			}
			subkey[size - 1] = temp0;
			break;
		case 2:
			for (int i = 0; i < size - 1; ++ i) {
				subkey[i] = subkey[i + 2];
			}
			subkey[size - 2] = temp0;
			subkey[size - 1] = temp1;
			break;
		default:
			break;
	}
}

// 擴充置換 expand_block[48] <-- plain_right[32]
void expand_permutation(char expand_block[], char plain_right[]) 
{
	for (int i = 0; i < 48; ++ i)
	{
		expand_block[i] = plain_right[ E_Table[i] ];
	}
}

// 壓縮置換後，得到48位的字密鑰
void compress_permutation(char comp_key[], char subkey[]) 
{
	for (int i = 0; i < 48; ++ i)
	{
		comp_key[i] = subkey[ PC_2[i] ];
	}
}

int char2int(char a[], int index, int offset) 
{
	int base = 1;
	int ret = 0;
	for (int i = offset - 1; i >= 0; -- i)
	{
		ret += (a[index + i] - '0') * base;
		base *= 2;
	}
	return ret;
}

void int2char(int num, char a[], int index, int offset)
{
	char temp[10];
	int i = 0;
	while(num) {
		temp[i] = num % 2 + '0';
		num = num / 2;
		++ i;
	}
	for (int j = 0; j < offset; ++ j)
	{
		a[index + j] = '0';
	}
	for (int j = 0; j < i; ++ j)
	{
		a[index + offset - j - 1] = temp[j];
	}
	//a[offset] = '\0';	
}

// S-盒置換 sbox_block[32] <-- expand_block[48] 
void sbox_substitution(char sbox_block[], char expand_block[]) 
{
	for (int i = 0; i < 8; ++ i)
	{
		int location = 0;
		char temp_int[2 + EXTRA_BITS];

		temp_int[0] = expand_block[i*6];
		temp_int[1] = expand_block[i*6 + 5];

		location += char2int(temp_int, 0, 2) * 16;
		location += char2int(expand_block, i * 6 + 1, 4);

		int2char(S[i][location], sbox_block, i * 4, 4);
	}
}

// P-盒置換 sbox
void pbox_substitution(char pbox_block[], char sbox_block[]) 
{
	for (int i = 0; i < 32; ++ i)
	{
		pbox_block[i] = sbox_block[ P_Table[i] ];
	}
}

void Xor(char c[], char a[], char b[], int size) 
{
	for (int i = 0; i < size; ++ i)
	{
		// 異或操作，相同為0，不同為1
		c[i] = (a[i] == b[i]) ? '0' : '1' ;
	}
}

void final_permutation(char cipher_block[], char plain_block[])
{
	for (int i = 0; i < 64; ++ i)
	{
		cipher_block[i] = plain_block[ IP_1_Table[i] ];
	}
}

// for debug
void myprint(const char *funcName, char *arr, int size, int columns) 
{
	cout << funcName << endl;
	for (int i = 0; i < size; ++ i)
	{
		cout << *(arr ++) ;

		if ( (i + 1) % columns == 0) {	
			cout << endl; 
		}
	}
	cout << endl;
}

void encryption(char myplain_block[], char cipher_block[], char key[]) {
	char plain_block[64 + EXTRA_BITS];
	char plain_left[32 + EXTRA_BITS];
	char plain_right[32 + EXTRA_BITS];

	char subkey[56 + EXTRA_BITS];
	char comp_key[48 + EXTRA_BITS];

	char expand_block[48 + EXTRA_BITS];
	char sbox_block[32 + EXTRA_BITS];
	char pbox_block[32 + EXTRA_BITS];

	mstrcpy(plain_block, myplain_block, 64);
	// 初始置換
	initial_permutation(plain_block);

	strncpy(plain_left, plain_block, 32);
	strncpy(plain_right, plain_block + 32, 32);

	// 置換選擇1, 得到初始子密鑰
	get_subkey(subkey, key);

	for (int i = 0; i < 16; ++ i)
	{

		// 将56位的subkey左移一位或者兩位
		shift_subkey(left_move_times[i], subkey, 28);
		shift_subkey(left_move_times[i], subkey + 28, 28);

		// 壓縮置換，又稱為置換選擇2，将56位的subkey壓縮成48位的comp_key
		compress_permutation(comp_key, subkey);
			
		// 擴充置換，将32位的 plain_right 擴充成48位
		expand_permutation(expand_block, plain_right);		

		// 異或操作
		Xor(expand_block, expand_block, comp_key, 48);

		// S盒替換
		sbox_substitution(sbox_block, expand_block);

		if (i == 0)
		{
			myprint("sbox_substitution", sbox_block, 32, 8);
		}

		// P盒替換
		pbox_substitution(pbox_block, sbox_block);
		
		if (i == 0)
		{
			myprint("pbox_substitution", pbox_block, 32, 8);
		}

		char temp_right[32 + EXTRA_BITS];
		mstrcpy(temp_right, plain_right, 32);

		// 異或操作
		Xor(plain_right, pbox_block, plain_left, 32);

		if (i == 0)
		{
			myprint("pbox_block", pbox_block, 32, 8);
			myprint("L0", plain_left, 32, 8);
			myprint("R1", plain_right, 32, 8);
		}

		mstrcpy(plain_left, temp_right, 32);	

		if (i == 0 || i == 15)
		{
			cout << i << endl;
			myprint("R1", plain_right, 32, 8);
			myprint("L1", plain_left, 32, 8);
		}

	}

	mstrcpy(plain_block, plain_left, 32);
	mstrcpy(plain_block + 32, plain_right, 32);

	// 末置換
	final_permutation(cipher_block, plain_block);
	
}

void decreption(char key[], char plain_block[], char cipher_block[]) 
{

}

test.cpp

/*
 * test.cpp
 * Halfish, 2014, December
 */

#include <iostream>
#include "des.h"
using namespace std;

int main(int argc, char const *argv[])
{
	char plain_block[64 + EXTRA_BITS];		// 明文塊
	char cipher_block[64 + EXTRA_BITS];		// 密文塊
	char key[64 + EXTRA_BITS];				// 密鑰

	strcpy(plain_block, "0000000100100011010001010110011110001001101010111100110111101111"); 
	strcpy(key, 		"0001001100110100010101110111100110011011101111001101111111110001");	
	
	encryption(plain_block, cipher_block, key);

	myprint("plain_block", plain_block, 64, 8);
	myprint("key", key, 64, 8);
	myprint("cipher_block", cipher_block, 64, 8);

	return 0;
}

DES 加密算法的實作

概述

繼續閱讀

Codeforces 1417 D. Make Them Equal(思維+構造)

查找算法之二分查找查找算法之二分查找

查找算法學習之二分查找（Python版本）——BinarySearch

CQ V1.0分詞bates(基于雙數組tire樹)—應該是目前最快的中文分詞算法

Command Network(POJ 3164)---定根最小樹形圖模闆題題目描述輸入格式輸出格式輸入樣例輸出樣例分析源程式

開源低帶寬語音編解碼器

241 Different Ways to Add Parentheses（C代碼版）

【趨高機器視覺】機器視覺技術原了解析及解決方案

CSMA/CD1． CSMA/CD的概述2． CSMA 的工作原理3． CSMA/CD控制規程及特點4． CSMA/CD協定5． CSMA/CD的優點6．結束語

極大似然法(ML)與最大期望法(EM)

C++ 第十五周報告1--《冒泡法排序》

筆試面試題目：滑動視窗(二)

資料結構與算法（27）——排序（二）

Dijkstra--簡易版（最短路徑）

GitHub連夜封殺！這份阿裡 10W 字内部 Java 字面試手冊到底有多強？

hdu7108哈希