什麼是對稱加密：對稱加密就是指，加密和解密使用同一個密鑰的加密方式。
發送方使用密鑰將明文數據加密成密文，然後發送出去，接收方收到密文後，使用同一個密鑰將密文解密成明文讀取。對稱加密計算量小、速度塊，適合對大量數據進行加密的場景。
常見的對稱加密算法有DES、3DES和AES。
對稱加密的缺點
密鑰傳輸問題：如上所說，由於對稱加密的加密和解密使用的是同一個密鑰，所以對稱加密的安全性就不僅僅取決於加密算法本身的強度，更取決於密鑰是否被安全的保管，因此加密者如何把密鑰安全的傳遞到解密者手裏，就成了對稱加密面臨的關鍵問題。密鑰一般都使用非對稱加密加密後再傳輸。
密鑰管理問題：再者隨着密鑰數量的增多，密鑰的管理問題會逐漸顯現出來。比如我們在加密用戶的信息時，不可能所有用戶都用同一個密鑰加密解密吧，這樣的話，一旦密鑰泄漏，就相當於泄露了所有用戶的信息，因此需要爲每一個用戶單獨的生成一個密鑰並且管理，這樣密鑰管理的代價也會非常大。會非常的耗費資源。
對稱加密的流程如下所示：
#include<stdio.h>
#include<string.h>
#include<unistd.h>
#include<stdlib.h>
#define Max 1024
int S[16][16] = ///s盒
{
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 S2[16][16] = ///逆s盒
{
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
};
///文件存儲區
void getString(char *str,int len) ///判斷文件內容的結尾的位置
{
int i=0;
int slen = read(0,str,len);
for(i=0; i<slen; i++,str++){
if(*str=='\n'){
*str='\0';
break;
}
}
}
void readPlainText(char *str,int *len) ///讀取文件內容的長度
{
int plen;
while(1){
getString(str,Max);
plen=strlen(str);
if(plen!=0&&plen%16==0){
printf("你輸入的明文爲:%s！\n",str);
break;
}
else
printf("明文長度必須爲16的倍數，現在的長度爲%d！\n",plen);
}
*len=plen;
}
void writeStrToFile(char *str, int len, char *fileName) ///將字符串寫入文件
{
FILE *fp;
int i = 0;
printf("Plain text is: %s\n", str);
fp = fopen(fileName, "wb");
for(i = 0; i < len; i++)
putc(str[i], fp);
fclose(fp);
}
void printASCCI(char *str, int len)///輸出字符串
{
int c, i = 0;
for(i = 0; i < len; i++){
c = (int)*str++;
c = c & 0x000000ff;
printf("The length of the plaintext must be a multiple of 16"
". The current length is 0x%x\n",c);
//明文長度必須爲16的倍數，現在的長度爲0x%x
}
}
int readStrFromFile(char *fileName, char *str) ///判斷解密文件是否存在
{
FILE *fp = fopen(fileName, "rb");
if(fp == NULL){
printf("%s %d \n",__func__,__LINE__);
printf("open file error！\n");
exit(0);
}
int i;
for(i = 0; i < Max && (str[i] = getc(fp)) != EOF; i++);
if(i >= Max){
printf("%s %d \n",__func__,__LINE__);
printf("file size too big！\n");
exit(0);
}
printf("%s %d %d\n",__func__,__LINE__,i);
str[i] = '\0';
fclose(fp);
return i;
}
///功能實現區
int checkKeyLen(int len) ///檢查密鑰長度
{
if(len == 16)
return 1;
else
return 0;
}
int getIntFromChar(char c) ///把一個字符化爲整型
{
int result = (int) c;
return result & 0x000000ff;
}
int getWordFromStr(char *str) ///密鑰擴展--密鑰化爲二進制
{
int one = getIntFromChar(str[0]);
one = one << 24;
int two = getIntFromChar(str[1]);
two = two << 16;
int three = getIntFromChar(str[2]);
three = three << 8;
int four = getIntFromChar(str[3]);
return one | two | three | four;
}
void splitIntToArray(int num, int array[4])
///把一個4字節的數的第一、二、三、四個字節取出，入進一個4個元素的整型數組裏面。
{
int one = num >> 24;
array[0] = one & 0x000000ff;
int two = num >> 16;
array[1] = two & 0x000000ff;
int three = num >> 8;
array[2] = three & 0x000000ff;
array[3] = num & 0x000000ff;
}
int mergeArrayToInt(int array[4])
///把數組中的第一、二、三和四元素分別作爲4字節整型的第一、二、三和四字節，合併成一個4字節整型
{
int one = array[0] << 24;
int two = array[1] << 16;
int three = array[2] << 8;
int four = array[3];
return one | two | three | four;
}
void leftLoop4int(int array[4], int step) ///將數組中的元素循環左移step位
{
int temp[4];
int i = 0;
for(i = 0; i < 4; i++)
temp[i] = array[i];
int index = step % 4 == 0 ? 0 : step % 4;
for(i = 0; i < 4; i++){
array[i] = temp[index];
index++;
index = index % 4;
}
}
void rightLoop4int(int array[4], int step) ///將數組循環右移step位
{
int temp[4];
int i = 0;
for(i = 0; i < 4; i++)
temp[i] = array[i];
int index = step % 4 == 0 ? 0 : step % 4;
index = 3 - index;
for(i = 3; i >= 0; i--){
array[i] = temp[index];
index--;
index = index == -1 ? 3 : index;
}
}
int getLeft4Bit(int num) ///獲取八比特的前四位，並化爲十六進制
{
int left = num & 0x000000f0;
return left >> 4;
}
int getRight4Bit(int num) ///獲取八比特的後四位，並化爲十六進制
{
return num & 0x0000000f;
}
int getNumFromSBox(int index) ///從s盒獲取元素
{
int row = getLeft4Bit(index);
int col = getRight4Bit(index);
return S[row][col];
}
int getNumFromS1Box(int index) ///從逆s盒獲取元素
{
int row = getLeft4Bit(index);
int col = getRight4Bit(index);
return S2[row][col];
}
int Rcon[10] = ///常量輪值表
{
0x01000000, 0x02000000,
0x04000000, 0x08000000,
0x10000000, 0x20000000,
0x40000000, 0x80000000,
0x1b000000, 0x36000000
};
int T(int num, int round) ///密鑰擴展的T函數
{
int numArray[4];
int i = 0;
splitIntToArray(num, numArray);
leftLoop4int(numArray, 1);//字循環
//字節代換
for(i = 0; i < 4; i++){
numArray[i] = getNumFromSBox(numArray[i]);
}
int result = mergeArrayToInt(numArray);
return result ^ Rcon[round];
}
int w[45];
void extendKey(char *key) ///擴展密鑰長度
{
int i = 0,j = 0;
for(i = 0; i < 4; i++){
w[i] = getWordFromStr(key + i * 4);
}
for(i = 4, j = 0; i < 44; i++){
if( i % 4 == 0){
w[i] = w[i - 4] ^ T(w[i - 1], j);
j++;//下一輪
}else{
w[i] = w[i - 4] ^ w[i - 1];
}
}
}
void convertToIntArray(char *str, int pa[4][4])
///把字符轉化爲字節並按矩陣排列，中字節排序，先上後下，在左後右
{
int k = 0,i = 0,j = 0;
for(i = 0; i < 4; i++){
for(j = 0; j < 4; j++){
pa[j][i] = getIntFromChar(str[k]);
k++;
}
}
}
void convertArrayToStr(int array[4][4], char *str) ///把字節轉換爲字符
{
int i = 0,j = 0;
for(i = 0; i < 4; i++){
for(j = 0; j < 4; j++)
*str++ = (char)array[j][i];
}
}
int colM[4][4] = ///列混合所用到的矩陣
{
2, 3, 1, 1,
1, 2, 3, 1,
1, 1, 2, 3,
3, 1, 1, 2
};
int deColM[4][4] = ///逆列混合所用到的矩陣
{
0xe, 0xb, 0xd, 0x9,
0x9, 0xe, 0xb, 0xd,
0xd, 0x9, 0xe, 0xb,
0xb, 0xd, 0x9, 0xe
};
int GFMul2(int s) ///GF上對應的值
{
int result = s << 1;
int a7 = result & 0x00000100;
if(a7 != 0){
result = result & 0x000000ff;
result = result ^ 0x1b;
}
return result;
}
int GFMul3(int s)
{
return GFMul2(s) ^ s;
}
int GFMul4(int s)
{
return GFMul2(GFMul2(s));
}
int GFMul8(int s)
{
return GFMul2(GFMul4(s));
}
int GFMul9(int s)
{
return GFMul8(s) ^ s;
}
int GFMul11(int s)
{
return GFMul9(s) ^ GFMul2(s);
}
int GFMul12(int s)
{
return GFMul8(s) ^ GFMul4(s);
}
int GFMul13(int s)
{
return GFMul12(s) ^ s;
}
int GFMul14(int s)
{
return GFMul12(s) ^ GFMul2(s);
}
int GFMul(int n, int s) ///GF上的二元運算
{
int result;
if(n == 1)
result = s;
else if(n == 2)
result = GFMul2(s);
else if(n == 3)
result = GFMul3(s);
else if(n == 0x9)
result = GFMul9(s);
else if(n == 0xb)//11
result = GFMul11(s);
else if(n == 0xd)//13
result = GFMul13(s);
else if(n == 0xe)//14
result = GFMul14(s);
return result;
}
///1.加密
void addRoundKey(int array[4][4], int round) ///輪密鑰加
{
int i = 0,j = 0;
int warray[4];
for(i = 0; i < 4; i++){
splitIntToArray(w[ round * 4 + i], warray);
for(j = 0; j < 4; j++){
array[j][i] = array[j][i] ^ warray[j];
}
}
}
void subBytes(int array[4][4]) ///字節代換
{
int i = 0,j = 0;
for(i = 0; i < 4; i++){
for(j = 0; j < 4; j++)
array[i][j] = getNumFromSBox(array[i][j]);
}
}
void shiftRows(int array[4][4]) ///行移位
{
int i = 0;
int rowTwo[4], rowThree[4], rowFour[4];
//複製狀態矩陣的第2,3,4行
for(i = 0; i < 4; i++){
rowTwo[i] = array[1][i];
rowThree[i] = array[2][i];
rowFour[i] = array[3][i];
}
//循環左移相應的位數
leftLoop4int(rowTwo, 1);
leftLoop4int(rowThree, 2);
leftLoop4int(rowFour, 3);
//把左移後的行復制回狀態矩陣中
for(i = 0; i < 4; i++){
array[1][i] = rowTwo[i];
array[2][i] = rowThree[i];
array[3][i] = rowFour[i];
}
}
void mixColumns(int array[4][4]) ///列混合
{
int tempArray[4][4];
int i = 0,j = 0;
for(i = 0; i < 4; i++){
for(j = 0; j < 4; j++)
tempArray[i][j] = array[i][j];
}
for(i = 0; i < 4; i++){
for(j = 0; j < 4; j++)
{
array[i][j] = GFMul(colM[i][0],tempArray[0][j]) ^ GFMul(colM[i][1],tempArray[1][j])
^ GFMul(colM[i][2],tempArray[2][j]) ^ GFMul(colM[i][3], tempArray[3][j]);
}
}
}
///2.解密
void deSubBytes(int array[4][4]) ///逆字節變換
{
int i = 0,j = 0;
for(i = 0; i < 4; i++){
for(j = 0; j < 4; j++)
array[i][j] = getNumFromS1Box(array[i][j]);
}
}
void deShiftRows(int array[4][4]) ///逆行移位
{
int i = 0;
int rowTwo[4], rowThree[4], rowFour[4];
for(i = 0; i < 4; i++){
rowTwo[i] = array[1][i];
rowThree[i] = array[2][i];
rowFour[i] = array[3][i];
}
rightLoop4int(rowTwo, 1);
rightLoop4int(rowThree, 2);
rightLoop4int(rowFour, 3);
for(i = 0; i < 4; i++){
array[1][i] = rowTwo[i];
array[2][i] = rowThree[i];
array[3][i] = rowFour[i];
}
}
void deMixColumns(int array[4][4]) ///逆列混合
{
int i = 0,j = 0;
int tempArray[4][4];
for(i = 0; i < 4; i++){
for(j = 0; j < 4; j++){
tempArray[i][j] = array[i][j];
}
}
for(i = 0; i < 4; i++){
for(j = 0; j < 4; j++){
array[i][j] = GFMul(deColM[i][0],tempArray[0][j]) ^ GFMul(deColM[i][1],tempArray[1][j])
^ GFMul(deColM[i][2],tempArray[2][j]) ^ GFMul(deColM[i][3], tempArray[3][j]);
}
}
}
void getArrayFrom4W(int i, int array[4][4]) ///從4個32位的密鑰字中獲得4X4數組，用於進行逆列混合
{
int index = i * 4;
int colOne[4], colTwo[4], colThree[4], colFour[4];
splitIntToArray(w[index], colOne);
splitIntToArray(w[index + 1], colTwo);
splitIntToArray(w[index + 2], colThree);
splitIntToArray(w[index + 3], colFour);
for(i = 0; i < 4; i++){
array[i][0] = colOne[i];
array[i][1] = colTwo[i];
array[i][2] = colThree[i];
array[i][3] = colFour[i];
}
}
void addRoundTowArray(int aArray[4][4],int bArray[4][4]) ///逆輪密鑰加
{
int i = 0,j = 0;
for(i = 0; i < 4; i++){
for(j = 0; j < 4; j++){
aArray[i][j] = aArray[i][j] ^ bArray[i][j];
}
}
}
void aes(char *p, int plen, char *key)///AES加密
{
int keylen=strlen(key);
int k = 0,i=0;
printf("%s %d %d \n",__func__,__LINE__,plen);
if(plen == 0 || plen % 16 != 0){
printf("%s %d \n",__func__,__LINE__);
printf("明文字符長度必須爲16的倍數！\n");
exit(0);
}
if(!checkKeyLen(keylen)){
printf("%s %d \n",__func__,__LINE__);
printf("密鑰字符長度錯誤！長度必須爲16、24和32。當前長度爲%d\n",keylen);
exit(0);
}
extendKey(key);//擴展密鑰
int pArray[4][4];
for(k = 0; k < plen; k += 16){
convertToIntArray(p + k, pArray);//變成矩陣
addRoundKey(pArray, 0);//一開始的輪密鑰加
for(i = 1; i < 10; i++) {//前9輪
subBytes(pArray);//字節代換
shiftRows(pArray);//行移位
mixColumns(pArray);//列混合
addRoundKey(pArray, i);//輪密鑰加
}
//第10輪
subBytes(pArray);//字節代換
shiftRows(pArray);//行移位
addRoundKey(pArray, 10);//輪密鑰加
convertArrayToStr(pArray, p + k);
}
}
void deAes(char *c, int clen, char *key) ///AES解密
{
int keylen = strlen(key);
int k = 0,i = 9;
if(clen == 0 || clen % 16 != 0){
printf("The ciphertext character must be a multiple of 16!"
" Now the length is %d\n",clen);
//密文字符長度必須爲16的倍數！現在的長度爲%d
exit(0);
}
if(!checkKeyLen(keylen)){
printf("Key character length is wrong! Must be 16, 24,"
" and 32 in length. Current length is %d\n",keylen);
//密鑰字符長度錯誤！長度必須爲16、24和32。當前長度爲
exit(0);
}
extendKey(key);//擴展密鑰
int cArray[4][4];
for(k = 0; k < clen; k += 16){
convertToIntArray(c + k, cArray); //字符轉化爲字節，並以矩陣形式排列
addRoundKey(cArray, 10); //輪密鑰加
int wArray[4][4];
for(i = 9; i >= 1; i--){
deSubBytes(cArray); //逆字節替換
deShiftRows(cArray);//逆行移位
deMixColumns(cArray); //逆列混合
getArrayFrom4W(i, wArray);
deMixColumns(wArray);//逆列混合
addRoundTowArray(cArray, wArray);//逆輪密鑰加
}
deSubBytes(cArray);//逆字節替換
deShiftRows(cArray);//逆行移位
addRoundKey(cArray, 0);//逆密鑰加
convertArrayToStr(cArray, c + k);
}
}
void aesStrToFile(char *key) ///s操作，輸入明文，並加密後保存在文件裏
{
char p[Max] = {"qweqwerasdfzxcvbnghrasdfzxqwerasdqwerasdfzxcvbnghfzxcvbnghcvbngh"};
int plen;
printf("Please enter your plaintext. The length of the plaintext characters must be a multiple of 16.\n");
//請輸入你的明文，明文字符長度必須爲16的倍數
plen = strlen(p);
printf("AES encryption..................\n");
//進行AES加密
aes(p, plen, key);//AES加密
printf("The encrypted ASCCI in plaintext is\n");
//加密完後的明文的ASCCI爲
printASCCI(p, plen);
char fileName[64]= {"save.txt"};
writeStrToFile(p, plen, fileName);
//已經將密文寫進%s中了,可以在運行該程序的當前目錄中找到它。
printf("The ciphertext has been written into %s, and it can be found in the current directory where the program is run.\n", fileName);
}
void deAesFile(char *key) ///p操作，將存有密文的文件進行解密，並保存在文件裏
{
char fileName[64] = {"save.txt"};
char c[Max];//密文字符串
printf("Please enter the name of the file to be decrypted, "
"the file must be in the same directory as the program\n");
int clen = readStrFromFile(fileName,c);
printf("Start decrypting.........\n");
//開始解密
deAes(c, clen, key);
printf("The decrypted plaintext ASCII is:\n");
//解密後的明文ASCII爲
printASCCI(c, clen);
printf("Plain text is: %s\n", c);
//明文爲：
writeStrToFile(c,clen,fileName);
printf("You can now open %s to view the decrypted ciphertext!\n",fileName);
//現在可以打開%s來查看解密後的密文了
}
void aesFile(char *key) ///f操作，將某文件裏的內容進行加密
{
char fileName[64] = {"encrypt.txt"};
char fileP[Max];
printf("Please enter the name of the file to be encrypted, the file must be in the same directory as the program\n");
readStrFromFile(fileName,fileP);
int plen = strlen(fileP);
printf("Start encryption.....\n");//開始加密
printf("The ASCII of the characters in the file before encryption is:%s\n",key);//加密前文件中字符的ASCII爲
printASCCI(fileP, plen);
aes(fileP, plen, key);//開始加密
printf("The encrypted ciphertext ASCII is:%s\n",key);//加密後的密文ASCII爲
printASCCI(fileP, plen);
writeStrToFile(fileP,plen,fileName);
printf("The encrypted ciphertext has been written into %s\n",fileName); //已經將加密後的密文寫進%s中了
}
enum func{
SAVE,
ENCRYPT,
DECODE,
};
static void usage(void)
{
printf("./test 0 ------------Encrypt string and save to file\n"
"./test 1 ------------Encrypted file\n"
"./test 2 ------------Decrypt file\n");
//輸入1表示要加密輸入的字符串,並將加密後的內容寫入到文件
//輸入2表示要加密文件
//輸入3表示要解密文件
exit(0);
}
int main(char argc, char *argv[])
{
char key[17]={"abcdefghigkilmrd"};
printf("Please enter a 16-character key\n");//輸入一個16字節的密鑰
if(argc < 2){
usage();
}
int klen;
while(1){
//getString(key,17);
klen = strlen(key);
if(klen != 16){
printf("Please enter a 16-character key,the length of the current key is %d\n",klen);
//輸入一個16字節的密鑰,當前密鑰長度爲
}else{
printf("The key you entered is:%s\n",key);//密鑰爲
break;
}
}
switch(atoi(argv[1])){
case SAVE:
aesStrToFile(key);//用AES加密字符串，並將字符串寫進文件中
break;
case ENCRYPT:
aesFile(key);//用AES加密文件
break;
case DECODE:
deAesFile(key);//把文件中的密文解密，並寫回文件中
break;
default:
usage();
break;
}
return 0;
}
測試步驟：
- 創建一個名爲encrypt.txt的文件，並且在文件中寫入一些字符，並且保證文件的長度是16的倍數
- 輸入./aes 1會將encrypt.txt文件加密，並且將加密後的內容重新寫入到encrypt.txt中，此時文件中的數據都是加密後的密文
- 輸入./aes 2會將encrypt.txt文件解密，解密出來的就是原來的明文數據，我們再比較下加密出來的原文和之前寫入到文件中的原文是否一致，如果一致則表示加密解密正常