DESアルゴリズムC言語実装

132815 ワード

DESアルゴリズムC言語実装
アルゴリズムの概要
DESアルゴリズムは対称ブロック暗号化法であり,暗号化と復号化の両方に長さ64ビットの鍵を用いる.64ビットを1パケット長とし、各パケットについて、置換、Feistel輪関数、サブ鍵生成などの一連の動作により、64ビットの暗号文を出力する.復号中は,サブキー入力の順序を交換することで,元の明文を解くことができる.
全体構造
  • 入力された64ビット暗号文を一度IP置換してL 0 R 0 L_を得る0R_0 L0​R0​
  • はIP置換の結果を16回反復し,反復の規則はL i=R(i−1),R i=L(i−1)f(R(i−1),K i)L_である.i = R_(i-1), R_i = L_(i-1)\bigoplus f(R_(i-1),K_i) Li​=R(​i−1),Ri​=L(​i−1)⨁f(R(​i−1),Ki​)
  • サブ鍵の生成は入力された64鍵を元にPC 1置換,循環シフト,PC 2置換などの過程を経て16個の48ビットのワード鍵を生成し,Feistel関数に順次入力する.
  • 16回の反復が完了した後、前32ビットと後32ビットの交換位置をIP逆置換し、最終的な暗号文を得る.

  • コード実装
  • tables.h:DESアルゴリズムプロセスで使用されるすべての配列を定義する
  • utility.h:すべてのモジュール関数の定義と実装
  • main.cpp:入出力を処理します.
  • #pragma once
    #include 
    
    int IP_Table[64] = {
    	58, 50, 42, 34, 26, 18, 10, 2,
    	60, 52, 44, 36, 28, 20, 12, 4,
    	62, 54, 46, 38, 30, 22, 14, 6,
    	64, 56, 48, 40, 32, 24, 16, 8,
    	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 };
    
    int IP_Reverse_Table[64] = {
    	40, 8, 48, 16, 56, 24, 64, 32,
    	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 };
    
    int Extension_Table[48] = {
    	32, 1, 2, 3, 4, 5,
    	4, 5, 6, 7, 8, 9,
    	8, 9, 10, 11, 12, 13,
    	12, 13, 14, 15, 16, 17,
    	16, 17, 18, 19, 20, 21,
    	20, 21, 22, 23, 24, 25,
    	24, 25, 26, 27, 28, 29,
    	28, 29, 30, 31, 32, 1 };
    
    int S_Box[8][64] = {
    	{
    		14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7,
    		0, 15, 7, 4, 15, 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
    	},
    	{
    		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
    	},
    	{
    		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
    	},
    	{
    		7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15,
    		12, 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
    	},
    	{
    		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
    	},
    	{
    		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
    	},
    	{
    		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
    	},
    	{
    		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
    	}
    };
    
    
    int PC1_Table[56] = {
    	57, 49, 41, 33, 25, 17, 9,
    	1, 58, 50, 42, 34, 26, 18,
    	10, 2, 59, 51, 43, 35, 27,
    	19, 11, 3, 60, 52, 44, 36,
    	63, 55, 47, 39, 31, 23, 15,
    	7, 62, 54, 46, 38, 30, 22,
    	14, 6, 61, 53, 45, 37, 29,
    	21, 13, 5, 28, 20, 12, 4 };
    
    int PC2_Table[48] = {
    	14, 17, 11, 24, 1, 5,
    	3, 28, 15, 6, 21, 10,
    	23, 19, 12, 4, 26, 8,
    	16, 7, 27, 20, 13, 2,
    	41, 52, 31, 37, 47, 55,
    	30, 40, 51, 45, 33, 48,
    	44, 49, 39, 56, 34, 53,
    	46, 42, 50, 36, 29, 32
    };
    
    int P_Table[32] = {
    	16, 7, 20, 21,
    	29, 12, 28, 17,
    	1, 15, 23, 26,
    	5, 18, 31, 10,
    	2, 8, 24, 14,
    	32, 27, 3, 9,
    	19, 13, 30, 6,
    	22, 11, 4, 25
    };
    
    
    #pragma once
    #include "tables.h"
    
    void charToBit(char * msg, int* msgBit) {
    	for (int i = 0; i < 8; i++) {
    		for (int j = 0; j < 8; j++) {
    			msgBit[(i + 1) * 8 - j - 1] = (msg[i] >> j) & 1;
    		}
    	}
    }
    
    void BitToChar(int* msgBit, char* msg) {
    	int sum = 0;
    	int count = 0;
    	for (int i = 0; i < 64; i++) {
    		sum = sum * 2 + msgBit[i];
    		if (i % 8 == 7) {
    			msg[count++] = sum;
    			sum = 0;
    		}
    	}
    }
    
    void IP_Permutation(int* input, int* output) {
    	for (int i = 0; i < 64; i++) {
    		output[i] = input[IP_Table[i] - 1];
    	}
    }
    
    void IP_Reverse_Permutation(int* input, int* output) {
    	for (int i = 0; i < 64; i++) {
    		output[i] = input[IP_Reverse_Table[i] - 1];
    	}
    }
    
    void devision(int* input, int *L, int* R) {
    	for (int i = 0; i < 32; i++) {
    		L[i] = input[i];
    		R[i] = input[i + 32];
    	}
    }
    
    void Extension(int* R, int* extendedR) {
    	for (int i = 0; i < 48; i++) {
    		extendedR[i] = R[Extension_Table[i] - 1];
    	}
    }
    
    void Xor48(int* R, int* subkey) {
    	for (int i = 0; i < 48; i++) {
    		if (R[i] != subkey[i]) {
    			R[i] = 1;
    		}
    		else {
    			R[i] = 0;
    		}
    	}
    }
    
    void Xor32(int* R, int* subkey) {
    	for (int i = 0; i < 32; i++) {
    		if (R[i] != subkey[i]) {
    			R[i] = 1;
    		}
    		else {
    			R[i] = 0;
    		}
    	}
    }
    
    void SBox(int* input, int start, int* output, int* SBox) {
    	int row = input[start] * 2 + input[start + 5];
    	int col = 0;
    	for (int i = 1; i <= 4; i++) {
    		col = col * 2 + input[start + i];
    	}
    	int result = SBox[row * 16 + col];
    	for (int i = 0; i < 4; i++) {
    		output[3 - i] = (result >> i) & 1;
    	}
    }
    
    void P_Permutation(int* input, int* output) {
    	for (int i = 0; i < 32; i++) {
    		output[i] = input[P_Table[i] - 1];
    	}
    }
    
    void Feistel(int* R, int* subkey, int* output) {
    	int extendedR[48] = { 0 };
    	Extension(R, extendedR);
    	Xor48(extendedR, subkey);
    
    	int SBoxResult[8][4] = { 0 };
    	for (int i = 0; i < 8; i++) {
    		SBox(extendedR, i * 6, SBoxResult[i], S_Box[i]);
    	}
    
    	// SBox      
    	int totalSBox[32] = { 0 };
    	for (int i = 0; i < 32; i++) {
    		totalSBox[i] = SBoxResult[i / 4][i % 4];
    	}
    	P_Permutation(totalSBox, output);
    }
    
    void leftShift(int* input) {
    	int first = input[0];
    	for (int i = 0; i < 27; i++) {
    		input[i] = input[i + 1];
    	}
    	input[27] = first;
    }
    
    void PC1(int* input, int* key) {
    	for (int i = 0; i < 56; i++) {
    		input[i] = key[PC1_Table[i] - 1];
    	}
    }
    
    void PC2(int* input, int* subkey) {
    	for (int i = 0; i < 48; i++) {
    		subkey[i] = input[PC2_Table[i] - 1];
    	}
    }
    
    void generateSubkeys(int key[64], int subkeys[16][48]) {
    	int pc1[56] = { 0 };
    	int pc2[56] = { 0 };
    	int C[28] = { 0 };
    	int D[28] = { 0 };
    
    	PC1(pc1, key);
    
    	for (int i = 0; i < 28; i++) {
    		C[i] = pc1[i];
    		D[i] = pc1[i + 28];
    	}
    
    	for (int i = 1; i < 17; i++) {
    		if (i == 1 || i == 2 || i == 9 || i == 16) {
    			leftShift(C);
    			leftShift(D);
    		}
    		else {
    			leftShift(C);
    			leftShift(C);
    			leftShift(D);
    			leftShift(D);
    		}
    
    		for (int i = 0; i < 28; i++) {
    			pc2[i] = C[i];
    			pc2[i + 28] = D[i];
    		}
    
    		PC2(pc2, subkeys[i - 1]);
    	}
    }
    
    void Swap(int* L, int * R) {
    	int* temp = L;
    	L = R;
    	R = temp;
    }
    
    void DES(int* msgBit, char* key) {
    
    	int keyBit[64] = { 0 };
    	int permutationBit[64] = { 0 };        //IP      
    	int L[32] = { 0 };                     // 32 
    	int R[32] = { 0 };                     // 32 
    	int subkeys[16][48] = { 0 };
    	int iterationL[32] = { 0 };            //    L R
    	int iterationR[32] = { 0 };
    	int cryptedMsg[64] = { 0 };
    
    	charToBit(key, keyBit);
    
    	IP_Permutation(msgBit, permutationBit);
    
    	devision(permutationBit, L, R);
    
    	generateSubkeys(keyBit, subkeys);
    
    	//  T
    	int FeistelResult[32] = { 0 };
    
    	for (int i = 0; i < 16; i++) {
    
    		for (int j = 0; j < 32; j++) {
    			iterationL[j] = R[j];
    			iterationR[j] = L[j];
    		}
    
    		Feistel(R, subkeys[i], FeistelResult);
    		Xor32(iterationR, FeistelResult);
    
    		for (int j = 0; j < 32; j++) {
    			L[j] = iterationL[j];
    			R[j] = iterationR[j];
    		}
    	}
    
    	//  L R      
    	int iterationTotal[64] = { 0 }; //       
    	for (int i = 0; i < 32; i++) {
    		iterationTotal[i] = iterationR[i];
    		iterationTotal[i + 32] = iterationL[i];
    	}
    	IP_Reverse_Permutation(iterationTotal, cryptedMsg);
    
    	printf("
    The crypeted message is :
    "
    ); for (int i = 0; i < 64; i++) { printf("%d", cryptedMsg[i]); } } void Decrypt(int* msgBit, char* key) { int keyBit[64] = { 0 }; int permutationBit[64] = { 0 }; //IP int L[32] = { 0 }; // 32 int R[32] = { 0 }; // 32 int subkeys[16][48] = { 0 }; int iterationL[32] = { 0 }; // L R int iterationR[32] = { 0 }; int decryptedBit[64] = { 0 }; charToBit(key, keyBit); IP_Permutation(msgBit, permutationBit); devision(permutationBit, L, R); generateSubkeys(keyBit, subkeys); // T int FeistelResult[32] = { 0 }; for (int i = 0; i < 16; i++) { for (int j = 0; j < 32; j++) { iterationL[j] = R[j]; iterationR[j] = L[j]; } Feistel(R, subkeys[15 - i], FeistelResult); Xor32(iterationR, FeistelResult); for (int j = 0; j < 32; j++) { L[j] = iterationL[j]; R[j] = iterationR[j]; } } // L R 。 int iterationTotal[64] = { 0 }; for (int i = 0; i < 32; i++) { iterationTotal[i] = iterationR[i]; iterationTotal[i + 32] = iterationL[i]; } IP_Reverse_Permutation(iterationTotal, decryptedBit); char decryptedMsg[9] = { 0 }; BitToChar(decryptedBit, decryptedMsg); printf("
    The decrypeted message is :
    "
    ); for (int i = 0; i < 8; i++) { printf("%c", decryptedMsg[i]); } printf("
    "
    ); }
    #include 
    #include 
    #include "utility.h"
    
    int main() {
    	char msg[9] = { 0 };
    	char key[9] = { 0 };
    
    	int msgBit[64] = { 0 };
    	
    	char cryptedMsg[65] = { 0 };
    	int cryptedMsgBit[64] = { 0 };
    
    	printf("Encrypting process

    "
    ); printf("Please enter the message:"); gets_s(msg); printf("Please enter the key:"); gets_s(key); charToBit(msg, msgBit); DES(msgBit, key); printf("

    Decrypting process

    "
    ); printf("Please enter the crypted message:
    "
    ); gets_s(cryptedMsg); for (int i = 0; i < 64; i++) { cryptedMsgBit[i] = cryptedMsg[i] - '0'; } printf("Please enter the key:"); gets_s(key); Decrypt(cryptedMsgBit,key); system("pause"); return 0; }