aes加密算法python語言實作_128位AES算法加密、解密檔案流程及C語言實作

前言

AES加密算法根據密鑰長度不同可分為128位，192位和256位，下面主要介紹128位對稱AES算法的實作。

AES算法流程

AES加密算法主要步驟有：

輪密鑰加：AddRoundKey

位元組替代：ByteSub

行移位： ShiftRow

列混肴： MixColumns

步驟詳解及實作代碼

我們用

明文：0123456789abcdeffedcba9876543210

密鑰：0f1571c947d9e8590cb7add6af7f6798

密文：ff0b844a0853bf7c6934ab4364148fb9

來示範。

将待加密/解密的輸入轉換成4x4矩陣，記為state;

1.位元組替代

位元組替代作用是将state矩陣的資料替換為S盒中的資料，state矩陣中每個元素的第一位作為S盒的行索引，第二位作為S盒的列索引。将擷取到的S盒中的值賦給state矩陣。

例如：state中某一進制素為ab，則用S盒中第a行第b列的資料0x62替換0xab。

過位元組替代後變為

S盒資料：

逆位元組替代就是用逆S盒來替換state矩陣中的資料，替換方法和位元組替代一緻。

逆S盒資料：

代碼：

void subBytes(int a[4][4], int encode){

// encode 為1 代表位元組替代，為0代表逆向位元組替代

for (int i = 0; i < 4; ++i) {

for (int j = 0; j < 4; ++j) {

int temp = a[i][j];

int row = temp / 16;

int column = temp % 16;

if (encode)

a[i][j] = S_BOX[row][column];

else

a[i][j] = INVERSE_S_BOX[row][column];

}

}

}

2.行移位

行移位操作是将矩陣的第k行循環左移k-1位。

經過行移位後變成

逆向行移位就是将矩陣的第k行循環右移k-1位。

代碼：

void shiftRows(int a[4][4], int encode){

//encode 為1代表行移位，為0代表逆向行移位

for (int i = 0; i < 4; ++i) {

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

if (encode) {

int temp = a[i][0];

a[i][0] = a[i][1];

a[i][1] = a[i][2];

a[i][2] = a[i][3];

a[i][3] = temp;

} else{

int temp = a[i][3];

a[i][3] = a[i][2];

a[i][2] = a[i][1];

a[i][1] = a[i][0];

a[i][0] = temp;

}

}

}

}

3.列混肴

首先介紹aes算法中的加法和乘法：

對于任意正整數c，都有

，再結合aes中的加法規則，便可得出任意兩個數相乘的結果。

例如：

列混淆變換是用一個常數矩陣去乘以矩陣state來得到新的state矩陣：

逆向列混淆使用另一個常數矩陣去乘以矩陣state來得到新的state矩陣：

代碼：

void mixColumns(int a[4][4], int encode){

//encode 為1代表列混淆，為0代表逆向列混淆

for (int i = 0; i < 4; ++i) {

int temp0 = a[0][i];

int temp1 = a[1][i];

int temp2 = a[2][i];

int temp3 = a[3][i];

if (encode) {

a[0][i] = aes_multiple(temp0, 2) ^ aes_multiple(temp1, 3) ^ temp2 ^ temp3;

a[1][i] = temp0 ^ (aes_multiple(temp1, 2)) ^ (temp2 ^ aes_multiple(temp2, 2)) ^ temp3;

a[2][i] = temp0 ^ temp1 ^ (aes_multiple(temp2, 2)) ^ (temp3 ^ aes_multiple(temp3, 2));

a[3][i] = temp0 ^ (aes_multiple(temp0, 2)) ^ temp1 ^ temp2 ^ aes_multiple(temp3, 2);

}else{

a[0][i] = aes_multiple(temp0, 14) ^ aes_multiple(temp1, 11) ^ aes_multiple(temp2, 13) ^ aes_multiple(temp3, 9);

a[1][i] = aes_multiple(temp0, 9) ^ aes_multiple(temp1, 14) ^ aes_multiple(temp2, 11) ^ aes_multiple(temp3, 13);

a[2][i] = aes_multiple(temp0, 13) ^ aes_multiple(temp1, 9) ^ aes_multiple(temp2, 14) ^ aes_multiple(temp3, 11);

a[3][i] = aes_multiple(temp0, 11) ^ aes_multiple(temp1, 13) ^ aes_multiple(temp2, 9) ^ aes_multiple(temp3, 14);

}

}

}

//AES乘法計算

int aes_multiple(int a, int le){

int thr = le & 0x8;

int sec = le & 0x4;

int fir = le & 0x2;

int fir_mod = le % 2;

int result = 0;

if (thr){

int b = a;

for (int i = 1; i <=3 ; ++i) {

b = b<<1;

if (b >= 256)

b = b ^ 0x11b;

}

b = b % 256;

result = result ^ b;

}

if (sec){

int b = a;

for (int i = 1; i <=2 ; ++i) {

b = b<<1;

if (b >= 256)

b = b ^ 0x11b;

}

b = b % 256;

result = result ^ b;

}

if (fir){

int b = a << 1;

if (b >= 256)

b = b ^ 0x11b;

b = b % 256;

result = result ^ b;

}

if (fir_mod)

result = result ^ a;

return result;

}

4.密鑰擴充

密鑰擴充将16位元組的密鑰擴充成11*16位元組。設k0k1k2...k15為輸入的密鑰。密鑰擴充流程圖如下圖：

我們将w[44]存儲到w[11][4][4]類型的數組中，密鑰擴充代碼如下：

void keyExpansion(int key[4][4], int w[11][4][4]){

for (int i = 0; i < 4; ++i) {

for (int j = 0; j < 4; ++j) {

w[0][i][j] = key[j][i];

}

}

for (int i = 1; i < 11; ++i){

for (int j = 0; j < 4; ++j) {

int temp[4];

if (j == 0){

temp[0] = w[i-1][3][1];

temp[1] = w[i-1][3][2];

temp[2] = w[i-1][3][3];

temp[3] = w[i-1][3][0];

for (int k = 0; k < 4; ++k) {

int m = temp[k];

int row = m / 16;

int column = m % 16;

temp[k] = S_BOX[row][column];

if (k == 0){

temp[k] = temp[k] ^ RC[i-1];

}

}

} else{

temp[0] = w[i][j-1][0];

temp[1] = w[i][j-1][1];

temp[2] = w[i][j-1][2];

temp[3] = w[i][j-1][3];

}

for (int l = 0; l < 4; ++l) {

w[i][j][l] = w[i-1][j][l] ^ temp[l];

}

}

}

}

5.輪密鑰加

輪密鑰加操作是将state矩陣與密鑰矩陣相加，即

代碼：

void addRoundKey(int a[4][4], int k[4][4]){

// 由于用w[11][4][4]表示W[44]導緻行列轉置，是以在進行異或操作的時候應該是a[i，j] 異或 k[j,i]

for (int i = 0; i < 4; ++i) {

for (int j = 0; j < 4; ++j) {

a[i][j] = a[i][j] ^ k[i][j];

}

}

}

總代碼

#include

#include

#include

void aes(char*, char*, char*, int);

void aes_detail(int[4][4], int[4][4], int);

void subBytes(int [4][4], int);

void shiftRows(int [4][4], int);

void mixColumns(int [4][4], int);

void addRoundKey(int [4][4], int[4][4]);

int aes_multiple(int, int);

void keyExpansion(int key[4][4], int w[11][4][4]);

int c2i(char );

static const int S_BOX[16][16] = { 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 };

static const int INVERSE_S_BOX[16][16] = { 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 };

int RC[10] = {0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36};

int main(){

int method = 0;//1表示加密， 0表示解密

//待加密/解密檔案存放路徑

char * source_path = "G:\\aes2.txt";

// 加密/解密後檔案存放路徑

char *des_path = "G:\\aes3.txt";

// 32位16進制密鑰

char * password = "0f1571c947d9e8590cb7add6af7f6798";

aes(source_path, des_path, password, method);

printf("success!!!!!!!!!!");

}

void aes(char* source_path, char* des_path, char* password, int method){

//将密鑰轉換成4*4數組

int p[4][4];

for (int m = 0; m < 4; ++m) {

for (int i = 0; i < 4; ++i) {

int indx = 4 * i + m;

p[i][m] = 16 * c2i(password[indx]) + c2i(password[indx + 1]);

}

}

FILE *file = fopen(source_path, "r"); //擷取檔案的指針

fseek(file, 0, SEEK_END); //移動檔案的指針到檔案結尾

int len = ftell(file); //擷取檔案的長度

rewind(file); //将檔案指針移動回檔案開始

// 如果檔案長度不是128位(16位元組)的整數倍，則補齊

int size = len;

if (len % 16 != 0) {

size = (len / 16 + 1) * 16;

}

unsigned char content[size];

//讀取檔案内容指派給content

fread(content, 1, len, file);

for (int j = len; j < size; ++j) {

content[j] = 0;

}

fclose(file);

//存儲結果

unsigned char encry[size];

//将檔案轉換成16位元組的int型數組加密、解密

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

int content_to_int[4][4];

for (int j = 0; j < 4; ++j) {

for (int k = 0; k < 4; ++k) {

content_to_int[j][k] = content[j * 4 + k + 16 * i];

}

}

aes_detail(content_to_int, p, method);

for (int j = 0; j < 4; ++j) {

for (int k = 0; k < 4; ++k) {

encry[j * 4 + k + 16 * i] = content_to_int[j][k];

}

}

}

FILE *file1 = fopen(des_path, "w");

fwrite(encry, size, 1, file1);

fflush(file1);

fclose(file1);

}

void aes_detail(int content[4][4], int password[4][4], int encode){

int p[11][4][4];

keyExpansion(password, p);

if (encode) {

addRoundKey(content, p[0]);

for (int i = 1; i <= 10; ++i) {

subBytes(content, encode);

shiftRows(content, encode);

if (i != 10) {

mixColumns(content, encode);

}

addRoundKey(content, p[i]);

}

}else {

addRoundKey(content, p[10]);

for (int i = 9; i >= 0; --i) {

shiftRows(content, encode);

subBytes(content, encode);

addRoundKey(content, p[i]);

if (i != 0) {

mixColumns(content, encode);

}

}

}

}

void subBytes(int a[4][4], int encode){

// encode 為1 代表位元組替代，為0代表逆向位元組替代

for (int i = 0; i < 4; ++i) {

for (int j = 0; j < 4; ++j) {

int temp = a[i][j];

int row = temp / 16;

int column = temp % 16;

if (encode)

a[i][j] = S_BOX[row][column];

else

a[i][j] = INVERSE_S_BOX[row][column];

}

}

}

void shiftRows(int a[4][4], int encode){

//encode 為1代表行移位，為0代表逆向行移位

for (int i = 0; i < 4; ++i) {

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

if (encode) {

int temp = a[i][0];

a[i][0] = a[i][1];

a[i][1] = a[i][2];

a[i][2] = a[i][3];

a[i][3] = temp;

} else{

int temp = a[i][3];

a[i][3] = a[i][2];

a[i][2] = a[i][1];

a[i][1] = a[i][0];

a[i][0] = temp;

}

}

}

}

void mixColumns(int a[4][4], int encode){

//encode 為1代表列混淆，為0代表逆向列混淆

for (int i = 0; i < 4; ++i) {

int temp0 = a[0][i];

int temp1 = a[1][i];

int temp2 = a[2][i];

int temp3 = a[3][i];

if (encode) {

a[0][i] = aes_multiple(temp0, 2) ^ aes_multiple(temp1, 3) ^ temp2 ^ temp3;

a[1][i] = temp0 ^ (aes_multiple(temp1, 2)) ^ (temp2 ^ aes_multiple(temp2, 2)) ^ temp3;

a[2][i] = temp0 ^ temp1 ^ (aes_multiple(temp2, 2)) ^ (temp3 ^ aes_multiple(temp3, 2));

a[3][i] = temp0 ^ (aes_multiple(temp0, 2)) ^ temp1 ^ temp2 ^ aes_multiple(temp3, 2);

}else{

a[0][i] = aes_multiple(temp0, 14) ^ aes_multiple(temp1, 11) ^ aes_multiple(temp2, 13) ^ aes_multiple(temp3, 9);

a[1][i] = aes_multiple(temp0, 9) ^ aes_multiple(temp1, 14) ^ aes_multiple(temp2, 11) ^ aes_multiple(temp3, 13);

a[2][i] = aes_multiple(temp0, 13) ^ aes_multiple(temp1, 9) ^ aes_multiple(temp2, 14) ^ aes_multiple(temp3, 11);

a[3][i] = aes_multiple(temp0, 11) ^ aes_multiple(temp1, 13) ^ aes_multiple(temp2, 9) ^ aes_multiple(temp3, 14);

}

}

}

void addRoundKey(int a[4][4], int k[4][4]){

// 由于用w[11][4][4]表示W[44]導緻行列轉置，是以在進行異或操作的時候應該是a[i，j] 異或 k[j,i]

for (int i = 0; i < 4; ++i) {

for (int j = 0; j < 4; ++j) {

a[i][j] = a[i][j] ^ k[j][i];

}

}

}

//AES乘法計算

int aes_multiple(int a, int le){

int thr = le & 0x8;

int sec = le & 0x4;

int fir = le & 0x2;

int fir_mod = le % 2;

int result = 0;

if (thr){

int b = a;

for (int i = 1; i <=3 ; ++i) {

b = b<<1;

if (b >= 256)

b = b ^ 0x11b;

}

b = b % 256;

result = result ^ b;

}

if (sec){

int b = a;

for (int i = 1; i <=2 ; ++i) {

b = b<<1;

if (b >= 256)

b = b ^ 0x11b;

}

b = b % 256;

result = result ^ b;

}

if (fir){

int b = a << 1;

if (b >= 256)

b = b ^ 0x11b;

b = b % 256;

result = result ^ b;

}

if (fir_mod)

result = result ^ a;

return result;

}

void keyExpansion(int key[4][4], int w[11][4][4]){

for (int i = 0; i < 4; ++i) {

for (int j = 0; j < 4; ++j) {

w[0][i][j] = key[j][i];

}

}

for (int i = 1; i < 11; ++i){

for (int j = 0; j < 4; ++j) {

int temp[4];

if (j == 0){

temp[0] = w[i-1][3][1];

temp[1] = w[i-1][3][2];

temp[2] = w[i-1][3][3];

temp[3] = w[i-1][3][0];

for (int k = 0; k < 4; ++k) {

int m = temp[k];

int row = m / 16;

int column = m % 16;

temp[k] = S_BOX[row][column];

if (k == 0){

temp[k] = temp[k] ^ RC[i-1];

}

}

} else{

temp[0] = w[i][j-1][0];

temp[1] = w[i][j-1][1];

temp[2] = w[i][j-1][2];

temp[3] = w[i][j-1][3];

}

for (int l = 0; l < 4; ++l) {

w[i][j][l] = w[i-1][j][l] ^ temp[l];

}

}

}

}

//将字元轉換為數值

int c2i(char ch) {

// 如果是數字，則用數字的ASCII碼減去48, 如果ch = '2' ,則 '2' - 48 = 2

if(isdigit(ch))

return ch - 48;

// 如果是字母，但不是A~F,a~f則傳回

if( ch < 'A' || (ch > 'F' && ch < 'a') || ch > 'z' )

return -1;

// 如果是大寫字母，則用數字的ASCII碼減去55, 如果ch = 'A' ,則 'A' - 55 = 10

// 如果是小寫字母，則用數字的ASCII碼減去87, 如果ch = 'a' ,則 'a' - 87 = 10

if(isalpha(ch))

return isupper(ch) ? ch - 55 : ch - 87;

return -1;

}