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AES.cpp
827 lines (548 loc) · 19.6 KB
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AES.cpp
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#include<stdio.h>
#include<string.h>
int Cipher_Round=0; // 加密運算執行回合數
int block=0; // 鑰匙的block數量
int mode; // 加解密方式
int count=0;// 做幾次加解密
unsigned char input[16]; // 加解密前字串
unsigned char output[16]; // 加解密後字串
unsigned char out_CO_8[16]; // CFB-8,OFB-8 加密後字串
unsigned char temp[16];
unsigned char IV[16]; // initialization vector
unsigned char process[4][4]; // 加密運算過程中的的矩陣
unsigned char Roundkey[240]; // 儲存主要鑰匙跟擴充鑰匙的陣列 ( 128...176, 192...208, 256...240 )
unsigned char key[32]; // 輸入的 Key
int S_Box[256] = {
0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16
};
int S_Box_Inverse[256] = {
0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,
0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,
0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,
0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,
0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,
0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,
0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,
0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d
};
/*
GF(2^8)
KeyExpansion 會用到
*/
int Rcon[11] = {
0x87, // 10000111
0x01, // 00000001
0x02, // 00000010
0x04, // 00000100
0x08, // 00001000
0x10, // 00010000
0x20, // 00100000
0x40, // 01000000 ,256
0x80, // 10000000 ,192
0x1b, // 00011011
0x36 // 00110110 ,128
};
/* KeyExpansion */
void KeyExpansion() {
unsigned char temp[4];
unsigned char t;
int count_Round_Key = 0; // 第幾個 round
// 第一回合 Key ( 128...0~15, 192...0~23, 256...0~31 )
for (int i=0;i<block;i++) {
Roundkey[i*4] = key[i*4];
Roundkey[i*4+1] = key[i*4+1];
Roundkey[i*4+2] = key[i*4+2];
Roundkey[i*4+3] = key[i*4+3];
}
// 產生其他回合鑰匙 ( 128...44 words, 192...52 words, 256...60 words )
for (int i=block;i<(4*(Cipher_Round+1));i++) {
// 前一個 word ( 4 bytes )
for (int j=0;j<4;j++) temp[j] = Roundkey[(i-1)*4+j];
if ((i%block)==0) {
// left shift
t = temp[0];
temp[0] = temp[1];
temp[1] = temp[2];
temp[2] = temp[3];
temp[3] = t;
// S-Box
temp[0] = S_Box[(int)temp[0]];
temp[1] = S_Box[(int)temp[1]];
temp[2] = S_Box[(int)temp[2]];
temp[3] = S_Box[(int)temp[3]];
// 跟 [rcon 00 00 00] XOR ( XOR最左邊的byte )
temp[0] ^= Rcon[i/block];
}
else if (block==8 && (i%block)==4) {
//only AES-256, S-Box
temp[0] = S_Box[(int)temp[0]];
temp[1] = S_Box[(int)temp[1]];
temp[2] = S_Box[(int)temp[2]];
temp[3] = S_Box[(int)temp[3]];
}
// 跟前 block*4 的 byte XOR ( ex: if 128... roundkey[16] = roundkey[0]^temp[0] )
Roundkey[i*4+0] = Roundkey[count_Round_Key*4+0]^temp[0];
Roundkey[i*4+1] = Roundkey[count_Round_Key*4+1]^temp[1];
Roundkey[i*4+2] = Roundkey[count_Round_Key*4+2]^temp[2];
Roundkey[i*4+3] = Roundkey[count_Round_Key*4+3]^temp[3];
count_Round_Key++;
}
}
/* AddRoundKey */
void AddRoundKey(int round) {
// 看round來使用key ( 一個 round = 16 bytes )
for (int i=0;i<4;i++) {
for (int j=0;j<4;j++) process[j][i] ^= Roundkey[(i*4+j)+(round*16)];
}
}
/* S-Box */
void Sub_S_Box() {
for (int i=0;i<4;i++) {
for (int j=0;j<4;j++) process[i][j] = S_Box[process[i][j]];
}
}
/* S-Box Inverse */
void Sub_S_Box_Inv() {
for (int i=0;i<4;i++) {
for (int j=0;j<4;j++) process[i][j] = S_Box_Inverse[process[i][j]];
}
}
/* left Shift (row) */
void ShiftRows() {
unsigned char temp;
// 2nd row ( 左移 1 個 )
temp = process[1][0];
process[1][0] = process[1][1];
process[1][1] = process[1][2];
process[1][2] = process[1][3];
process[1][3] = temp;
// 3th row ( 左移 2 個 )
temp = process[2][0];
process[2][0] = process[2][2];
process[2][2] = temp;
temp = process[2][1];
process[2][1] = process[2][3];
process[2][3] = temp;
// 4th row ( 左移 3 個 )
temp = process[3][0];
process[3][0] = process[3][3];
process[3][3] = process[3][2];
process[3][2] = process[3][1];
process[3][1] = temp;
}
/* right Shift inverse (row) */
void ShiftRows_Inv() {
unsigned char temp;
// 2nd row ( 右移 1 個 )
temp = process[1][3];
process[1][3] = process[1][2];
process[1][2] = process[1][1];
process[1][1] = process[1][0];
process[1][0] = temp;
// 3th row ( 右移 2 個 )
temp = process[2][0];
process[2][0] = process[2][2];
process[2][2] = temp;
temp = process[2][1];
process[2][1] = process[2][3];
process[2][3] = temp;
// 4th row ( 右移 3 個 )
temp = process[3][0];
process[3][0] = process[3][1];
process[3][1] = process[3][2];
process[3][2] = process[3][3];
process[3][3] = temp;
}
/*
shift XOR 乘法
(x << 1) shift 1 bit
(x >> 7) 第8個bit
(x >> 7) & 0x01 檢查第8個bit是否為 1
0x1b = 0001 1011 ( x^4 + x^3 + x + 1 )
*/
unsigned char SXOR(unsigned char x) {
return ((x << 1) ^ (((x >> 7) & 0x01)*0x1b));
}
/* MixColumns */
void MixColumns() {
unsigned char t0,t1,t2,t3;
for (int i=0;i<4;i++) {
t0 = process[0][i];
t1 = process[1][i];
t2 = process[2][i];
t3 = process[3][i];
// (02*process[0][i])^(03*process[1][i])^process[2][i]^process[3][i]
process[0][i] = SXOR(t0)^(t1^SXOR(t1))^t2^t3;
// process[0][i]^(02*process[1][i])^(03*process[2][i])^process[3][i]
process[1][i] = t0^SXOR(t1)^(t2^SXOR(t2))^t3;
// process[0][i]^process[1][i]^(02*process[2][i])^(03*process[3][i])
process[2][i] = t0^t1^SXOR(t2)^(t3^SXOR(t3));
// (03*process[0][i])^process[1][i]^process[2][i]^(02*process[3][i])
process[3][i] = (t0^SXOR(t0))^t1^t2^SXOR(t3);
}
}
/* InvMixColumns */
void MixColumns_Inv() {
unsigned char t0,t1,t2,t3;
unsigned char tt0,tt1,tt2,tt3;
for (int i=0;i<4;i++) {
t0 = process[0][i];
t1 = process[1][i];
t2 = process[2][i];
t3 = process[3][i];
// (0E*process[0][i])^(0B*process[1][i])^(0D*process[2][i])^(09*process[3][i])
tt0 = SXOR(t0)^SXOR(SXOR(t0))^SXOR(SXOR(SXOR(t0)));
tt1 = t1^SXOR(t1)^SXOR(SXOR(SXOR(t1)));
tt2 = t2^SXOR(SXOR(t2))^SXOR(SXOR(SXOR(t2)));
tt3 = t3^SXOR(SXOR(SXOR(t3)));
process[0][i] = tt0^tt1^tt2^tt3;
// (09*process[0][i])^(09*process[1][i])^(0B*process[2][i])^(0D*process[3][i])
tt0 = t0^SXOR(SXOR(SXOR(t0)));
tt1 = SXOR(t1)^SXOR(SXOR(t1))^SXOR(SXOR(SXOR(t1)));
tt2 = t2^SXOR(t2)^SXOR(SXOR(SXOR(t2)));
tt3 = t3^SXOR(SXOR(t3))^SXOR(SXOR(SXOR(t3)));
process[1][i] = tt0^tt1^tt2^tt3;
// (0D*process[0][i])^(09*process[1][i])^(0E*process[2][i])^(0B*process[3][i])
tt0 = t0^SXOR(SXOR(t0))^SXOR(SXOR(SXOR(t0)));
tt1 = t1^SXOR(SXOR(SXOR(t1)));
tt2 = SXOR(t2)^SXOR(SXOR(t2))^SXOR(SXOR(SXOR(t2)));
tt3 = t3^SXOR(t3)^SXOR(SXOR(SXOR(t3)));
process[2][i] = tt0^tt1^tt2^tt3;
// (0B*process[0][i])^(0D*process[1][i])^(09*process[2][i])^(0E*process[3][i])
tt0 = t0^SXOR(t0)^SXOR(SXOR(SXOR(t0)));
tt1 = t1^SXOR(SXOR(t1))^SXOR(SXOR(SXOR(t1)));
tt2 = t2^SXOR(SXOR(SXOR(t2)));
tt3 = SXOR(t3)^SXOR(SXOR(t3))^SXOR(SXOR(SXOR(t3)));
process[3][i] = tt0^tt1^tt2^tt3;
}
}
/* 加密 */
void Encryption() {
// input 轉換成 column 型式
for (int i=0;i<4;i++) {
for (int j=0;j<4;j++) {
if(mode==0 || mode==1) process[j][i] = input[i*4+j];
else if (mode==3 || mode==5 || mode==6) process[j][i] = IV[i*4+j];
}
}
AddRoundKey(0);
//CBC
if (mode==1) {
for (int i=0;i<4;i++) {
for (int j=0;j<4;j++) {
if (count==1) process[j][i] ^= IV[i*4+j];
else process[j][i] ^= output[i*4+j];
}
}
}
for (int round=1;round<Cipher_Round;round++) {
Sub_S_Box();
ShiftRows();
MixColumns();
AddRoundKey(round);
}
Sub_S_Box();
ShiftRows();
AddRoundKey(Cipher_Round);
for(int i=0;i<4;i++) {
for(int j=0;j<4;j++) output[i*4+j]=process[j][i];
}
}
/* 解密 */
void Decryption() {
// input 轉換成 column 型式
for (int i=0;i<4;i++) {
for (int j=0;j<4;j++) {
if(mode==0 || mode==1) process[j][i] = input[i*4+j];
}
}
AddRoundKey(Cipher_Round);
for (int round=Cipher_Round-1;round>0;round--) {
ShiftRows_Inv();
Sub_S_Box_Inv();
AddRoundKey(round);
MixColumns_Inv();
}
ShiftRows_Inv();
Sub_S_Box_Inv();
AddRoundKey(0);
//CBC
if (mode==1) {
for (int i=0;i<4;i++) {
for (int j=0;j<4;j++) {
if (count==1) process[j][i] ^= IV[i*4+j];
else process[j][i] ^= temp[i*4+j];
}
}
}
for(int i=0;i<4;i++) {
for(int j=0;j<4;j++) output[i*4+j]=process[j][i];
}
}
/* 檢查輸入 character 正確於否 */
int Input(unsigned char *inputArray, int num) {
char check[num];
char check_again;
int dcheck=0;
for (int cha=0;cha<num;cha++) {
scanf("%c",&inputArray[cha]);
check[cha] = inputArray[cha];
// 檢查輸入的 character 是否為 enter 鍵
if (inputArray[cha]=='\n') return 0;
}
// 檢查有沒有超過 character 數量
while (true) {
scanf("%c",&check_again);
if (check_again=='\n') break;
dcheck++;
}
if (dcheck==0) return 1;
else return 0;
}
int main () {
int EoD; // encryption or decryption
int check; // 檢查輸入的 character 是否正確
char enter; // 吃 enter 鍵
char c; // 抓看看 file 裡下一個是否有 character
int Key_size=0;
int flag=0; // 看 file 裡還有沒有 character
unsigned char input_key[32]; // 存 key
while (true) {
printf("Encryption(1) or Decryption(0): ");
scanf("%d",&EoD);
if (EoD<0 || EoD>1) printf("\n 1 OR 0 \n\n");
else break;
}
while (true) {
printf("\n選擇模式\n( ECB: 0 CBC: 1 CFB-1: 2 CFB-8: 3 OFB-1: 4 OFB-8: 5 CTR: 6 ):");
scanf("%d",&mode);
scanf("%c",&enter);
if ( (mode<0) || (mode>6) ) {
printf("\n[ Please enter 0 ~ 6 ]\n\n");
continue;
}
else if (mode!=0) {
while (true) {
printf("\n輸入 Initialization Vector ( 16 characters ):");
check = Input(IV,16);
if (check==0) {
printf("\n[ 請輸入指定 character 數 ]\n\n");
continue;
}
else break;
}
}
break;
}
if (EoD==1) printf("\n~ AES Encryption ~\n");
else printf("\n~ AES Decryption ~\n");
while (true) {
printf("輸入 AES key size ( 128 , 192 , 256) : ");
scanf("%d",&Key_size);
scanf("%c",&enter);
if (Key_size!=128 && Key_size!=192 && Key_size!=256) printf("\n[ Please enter 128 , 192 or 256 ]\n\n");
else break;
}
block=Key_size/32; // key block數量 ( 128...4, 192...6, 256...8 )
Cipher_Round=block+6; // 回和數
while (true) {
if (Key_size==128) {
printf("\n輸入 AES KEY (16 characters) : ");
check = Input(key,16);
}
else if (Key_size==192) {
printf("\n輸入 AES KEY (24 characters) : ");
check = Input(key,24);
}
else if (Key_size==256) {
printf("\n輸入 AES KEY (32 characters) : ");
check = Input(key,32);
}
if (check==1) break;
else printf("\n[ 請輸入指定 character 數 ]\n\n");
}
KeyExpansion();
// 加密
if (EoD==1) {
char file[30];
FILE *fp,*wp;
while (true) {
printf("\n輸入 plaintext file name => ");
scanf("%s", &file);
// 找 file
if ((fp=fopen(file,"rb"))==NULL) {
printf("\n[ 找不到此檔案 ]\n");
continue;
}
break;
}
printf("\n輸入 Ciphertext file name => ");
scanf("%s",&file);
wp=fopen(file,"wb");
flag=1;
while(flag==1) {
count++; //第幾次加密
for (int c=0;c<16;c++) {
input[c] = fgetc(fp); // 從 file 抓一個 character
// 最後讀取時剩下的陣列內容設為 0
if (feof(fp)) {
for (int padding = c;padding<16;padding++) input[padding] = 0x00;
flag = 0; // 表示 file 裡 character 以抓完
}
}
// CFB-8
if (mode==3) {
for (int i=0;i<16;i++) {
Encryption();
temp[0] = output[0];
temp[0] ^= input[i];
out_CO_8[i] = temp[0]; // 只保留最左邊 1 byte ( 8 bits )
// 新 IV
for (int j=0;j<15;j++) IV[j] = IV[j+1];
IV[15] = temp[0];
}
}
// OFB-8
else if (mode==5) {
for (int i=0;i<16;i++) {
Encryption();
temp[0] = output[0];
// 新 IV
for (int j=0;j<15;j++) IV[j] = IV[j+1];
IV[15] = temp[0];
temp[0] ^= input[i];
out_CO_8[i] = temp[0]; // 只保留最左邊 1 byte ( 8 bits )
}
}
else Encryption();
// CTR
if (mode==6) {
for (int i=15;i>=0;i--) {
// 進位
if (IV[i]==255) {
IV[i] == 0;
continue;
}
IV[i]++; //counter + 1
}
for (int i=0;i<16;i++) output[i] ^= input[i];
}
// 密文輸出到檔案上
for(int c=0;c<16;c++) {
if (mode==3 || mode==5) fprintf(wp,"%c",out_CO_8[c]);
else fprintf(wp,"%c",output[c]);
}
if ((c=fgetc(fp))==EOF) flag = 0;
else ungetc(c, fp);
}
fclose(fp);
rewind(wp);
fclose(wp);
}
// 解密
else {
char file[50];
FILE *fp,*wp;
while (true) {
printf("\n輸入 Ciphertext file name => ");
scanf("%s",&file);
// 找 file
if ((fp = fopen(file,"rb"))==NULL) {
printf("\n[ 找不到此檔案 ]\n");
continue;
}
break;
}
printf("\n輸入 Plaintext file name => ");
scanf("%s", &file);
wp = fopen(file,"wb");
flag = 1;
while(flag==1) {
count++; //第幾次解密
if (mode==1) for (int i=0;i<16;i++) temp[i] = input[i];
for (int c=0;c<16;c++) input[c] = fgetc(fp);
// CFB-8
if (mode==3) {
for (int i=0;i<16;i++) {
Encryption();
temp[0] = input[i];
// 新 IV
for (int j=0;j<15;j++) IV[j] = IV[j+1];
IV[15] = temp[0];
temp[0] ^= output[0];
out_CO_8[i] = temp[0]; // 只保留最左邊 1 byte ( 8 bits )
}
}
// OFB-8
else if (mode==5) {
for (int i=0;i<16;i++) {
Encryption();
temp[0] = output[0];
// 新 IV
for (int j=0;j<15;j++) IV[j] = IV[j+1];
IV[15] = temp[0];
temp[0] ^= input[i];
out_CO_8[i] = temp[0]; // 只保留最左邊 1 byte ( 8 bits )
}
}
// CTR
else if (mode==6) {
Encryption();
for (int i=15;i>=0;i--) {
// 進位
if (IV[i]==255) {
IV[i] == 0;
continue;
}
IV[i]++; //counter + 1
}
for (int i=0;i<16;i++) output[i] ^= input[i];
}
else Decryption();
for (int c=0;c<16;c++) {
// 處理後面空白字
if (output[c]==0x00 && (mode==0 || mode==1) ) {
flag = 0;
break;
}
else if (out_CO_8[c]==0x00 && (mode==3 || mode==5) ) {
flag = 0;
break;
}
if (mode==3 || mode==5) fprintf(wp,"%c",out_CO_8[c]);
else fprintf(wp,"%c",output[c]);
}
if ((c = fgetc(fp)) == EOF) flag = 0;
else ungetc(c, fp);
}
fclose(fp);
rewind(wp);
fclose(wp);
}
if (EoD == 1) printf("\nEncryption process success !! \n");
else printf("\nDecryption process success !! \n");
return 0;
}