【密码学】C语言实现AES核心步骤

Python010

【密码学】C语言实现AES核心步骤,第1张

按照AES算法,完成AES算法S盒、行移位、列混合、轮密钥加操作

高级加密标准(英语:Advanced Encryption Standard,缩写:AES),在密码学中又称Rijndael加密法,是美国联邦政府采用的一种区块加密标准。这个标准用来替代原先的DES,已经被多方分析且广为全世界所使用。经过五年的甄选流程,高级加密标准由美国国家标准与技术研究院(NIST)于2001年11月26日发布于FIPS PUB 197,并在2002年5月26日成为有效的标准。2006年,高级加密标准已然成为对称密钥加密中最流行的算法之一。

AES采用对称分组密码体制,密钥的长度最少支持为128、192、256,分组长度128位,算法应易于各种硬件和软件实现。

AES加密数据块分组长度必须为128比特,密钥长度可以是128比特、192比特、256比特中的任意一个(如果数据块及密钥长度不足时,会补齐)。AES加密有很多轮的重复和变换。大致步骤如下:1、密钥扩展(KeyExpansion),2、初始轮(Initial Round),3、重复轮(Rounds),每一轮又包括:字节替代(SubBytes)、行移位(ShiftRows)、列混合(MixColumns)、轮密钥加(AddRoundKey),4、最终轮(Final Round),最终轮没有MixColumns。

AES算法的加密整体结构

字节替代(SubBytes):使用一个S盒进行非线性置换,S盒是一个16×16的矩阵,如表4-9所示。字节替代将输入的状态矩阵的每一个字节通过一个简单查表操作,映射为另外一个字节。

输入字节的前4bits指定S盒的行值,后4bits指定S盒的列值,行和列所确定S盒位置的元素作为输出,例如输入字节“03”,行值为0,列值为3,根据表4-9可知第0行第3列对应的值为 “7B”,因此输出字节为“7B”。

举例

在上面的示例中,第1个基本元素为”F5”,它将被S盒行为第”F行”、列为第”5”列的元素“E6“代替,其余的输出也用相同的方法确定。

状态阵列的4个行循环以字节为基本单位进行左移,而每行循环做移的偏移量是由明文分组的大小和所在行数共同确定,即列数Nb和行号确定。

举例

举例

轮密钥加操作是将密钥与明文按比特异或,轮密钥通过密钥扩展得到

和fips-192(AES)的标准一样

完整的!

#include "stdio.h"

#include "memory.h"

#include "time.h"

#include "stdlib.h"

#define PLAIN_FILE_OPEN_ERROR -1

#define KEY_FILE_OPEN_ERROR -2

#define CIPHER_FILE_OPEN_ERROR -3

#define OK 1

typedef char ElemType

/*初始置换表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}

/*逆初始置换表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}

/*扩充置换表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}

/*置换函数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][4][16] =

/*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}}}

/*置换选择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}

/*置换选择2*/

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}

/*对左移次数的规定*/

int MOVE_TIMES[16] = {1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1}

int ByteToBit(ElemType ch,ElemType bit[8])

int BitToByte(ElemType bit[8],ElemType *ch)

int Char8ToBit64(ElemType ch[8],ElemType bit[64])

int Bit64ToChar8(ElemType bit[64],ElemType ch[8])

int DES_MakeSubKeys(ElemType key[64],ElemType subKeys[16][48])

int DES_PC1_Transform(ElemType key[64], ElemType tempbts[56])

int DES_PC2_Transform(ElemType key[56], ElemType tempbts[48])

int DES_ROL(ElemType data[56], int time)

int DES_IP_Transform(ElemType data[64])

int DES_IP_1_Transform(ElemType data[64])

int DES_E_Transform(ElemType data[48])

int DES_P_Transform(ElemType data[32])

int DES_SBOX(ElemType data[48])

int DES_XOR(ElemType R[48], ElemType L[48],int count)

int DES_Swap(ElemType left[32],ElemType right[32])

int DES_EncryptBlock(ElemType plainBlock[8], ElemType subKeys[16][48], ElemType cipherBlock[8])

int DES_DecryptBlock(ElemType cipherBlock[8], ElemType subKeys[16][48], ElemType plainBlock[8])

int DES_Encrypt(char *plainFile, char *keyStr,char *cipherFile)

int DES_Decrypt(char *cipherFile, char *keyStr,char *plainFile)

/*字节转换成二进制*/

int ByteToBit(ElemType ch, ElemType bit[8]){

int cnt

for(cnt = 0cnt <8cnt++){

*(bit+cnt) = (ch>>cnt)&1

}

return 0

}

/*二进制转换成字节*/

int BitToByte(ElemType bit[8],ElemType *ch){

int cnt

for(cnt = 0cnt <8cnt++){

*ch |= *(bit + cnt)<<cnt

}

return 0

}

/*将长度为8的字符串转为二进制位串*/

int Char8ToBit64(ElemType ch[8],ElemType bit[64]){

int cnt

for(cnt = 0cnt <8cnt++){

ByteToBit(*(ch+cnt),bit+(cnt<<3))

}

return 0

}

/*将二进制位串转为长度为8的字符串*/

int Bit64ToChar8(ElemType bit[64],ElemType ch[8]){

int cnt

memset(ch,0,8)

for(cnt = 0cnt <8cnt++){

BitToByte(bit+(cnt<<3),ch+cnt)

}

return 0

}

/*生成子密钥*/

int DES_MakeSubKeys(ElemType key[64],ElemType subKeys[16][48]){

ElemType temp[56]

int cnt

DES_PC1_Transform(key,temp)/*PC1置换*/

for(cnt = 0cnt <16cnt++){/*16轮跌代,产生16个子密钥*/

DES_ROL(temp,MOVE_TIMES[cnt])/*循环左移*/

DES_PC2_Transform(temp,subKeys[cnt])/*PC2置换,产生子密钥*/

}

return 0

}

/*密钥置换1*/

int DES_PC1_Transform(ElemType key[64], ElemType tempbts[56]){

int cnt

for(cnt = 0cnt <56cnt++){

tempbts[cnt] = key[PC_1[cnt]]

}

return 0

}

/*密钥置换2*/

int DES_PC2_Transform(ElemType key[56], ElemType tempbts[48]){

int cnt

for(cnt = 0cnt <48cnt++){

tempbts[cnt] = key[PC_2[cnt]]

}

return 0

}

/*循环左移*/

int DES_ROL(ElemType data[56], int time){

ElemType temp[56]

/*保存将要循环移动到右边的位*/

memcpy(temp,data,time)

memcpy(temp+time,data+28,time)

/*前28位移动*/

memcpy(data,data+time,28-time)

memcpy(data+28-time,temp,time)

/*后28位移动*/

memcpy(data+28,data+28+time,28-time)

memcpy(data+56-time,temp+time,time)

return 0

}

/*IP置换*/

int DES_IP_Transform(ElemType data[64]){

int cnt

ElemType temp[64]

for(cnt = 0cnt <64cnt++){

temp[cnt] = data[IP_Table[cnt]]

}

memcpy(data,temp,64)

return 0

}

/*IP逆置换*/

int DES_IP_1_Transform(ElemType data[64]){

int cnt

ElemType temp[64]

for(cnt = 0cnt <64cnt++){

temp[cnt] = data[IP_1_Table[cnt]]

}

memcpy(data,temp,64)

return 0

}

/*扩展置换*/

int DES_E_Transform(ElemType data[48]){

int cnt

ElemType temp[48]

for(cnt = 0cnt <48cnt++){

temp[cnt] = data[E_Table[cnt]]

}

memcpy(data,temp,48)

return 0

}

/*P置换*/

int DES_P_Transform(ElemType data[32]){

int cnt

ElemType temp[32]

for(cnt = 0cnt <32cnt++){

temp[cnt] = data[P_Table[cnt]]

}

memcpy(data,temp,32)

return 0

}

/*异或*/

int DES_XOR(ElemType R[48], ElemType L[48] ,int count){

int cnt

for(cnt = 0cnt <countcnt++){

R[cnt] ^= L[cnt]

}

return 0

}

/*S盒置换*/

int DES_SBOX(ElemType data[48]){

int cnt

int line,row,output

int cur1,cur2

for(cnt = 0cnt <8cnt++){

cur1 = cnt*6

cur2 = cnt<<2

/*计算在S盒中的行与列*/

line = (data[cur1]<<1) + data[cur1+5]

row = (data[cur1+1]<<3) + (data[cur1+2]<<2)

+ (data[cur1+3]<<1) + data[cur1+4]

output = S[cnt][line][row]

/*化为2进制*/

data[cur2] = (output&0X08)>>3

data[cur2+1] = (output&0X04)>>2

data[cur2+2] = (output&0X02)>>1

data[cur2+3] = output&0x01

}

return 0

}

/*交换*/

int DES_Swap(ElemType left[32], ElemType right[32]){

ElemType temp[32]

memcpy(temp,left,32)

memcpy(left,right,32)

memcpy(right,temp,32)

return 0

}

/*加密单个分组*/

int DES_EncryptBlock(ElemType plainBlock[8], ElemType subKeys[16][48], ElemType cipherBlock[8]){

ElemType plainBits[64]

ElemType copyRight[48]

int cnt

Char8ToBit64(plainBlock,plainBits)

/*初始置换(IP置换)*/

DES_IP_Transform(plainBits)

/*16轮迭代*/

for(cnt = 0cnt <16cnt++){

memcpy(copyRight,plainBits+32,32)

/*将右半部分进行扩展置换,从32位扩展到48位*/

DES_E_Transform(copyRight)

/*将右半部分与子密钥进行异或操作*/

DES_XOR(copyRight,subKeys[cnt],48)

/*异或结果进入S盒,输出32位结果*/

DES_SBOX(copyRight)

/*P置换*/

DES_P_Transform(copyRight)

/*将明文左半部分与右半部分进行异或*/

DES_XOR(plainBits,copyRight,32)

if(cnt != 15){

/*最终完成左右部的交换*/

DES_Swap(plainBits,plainBits+32)

}

}

/*逆初始置换(IP^1置换)*/

DES_IP_1_Transform(plainBits)

Bit64ToChar8(plainBits,cipherBlock)

return 0

}

/*解密单个分组*/

int DES_DecryptBlock(ElemType cipherBlock[8], ElemType subKeys[16][48],ElemType plainBlock[8]){

ElemType cipherBits[64]

ElemType copyRight[48]

int cnt

Char8ToBit64(cipherBlock,cipherBits)

/*初始置换(IP置换)*/

DES_IP_Transform(cipherBits)

/*16轮迭代*/

for(cnt = 15cnt >= 0cnt--){

memcpy(copyRight,cipherBits+32,32)

/*将右半部分进行扩展置换,从32位扩展到48位*/

DES_E_Transform(copyRight)

/*将右半部分与子密钥进行异或操作*/

DES_XOR(copyRight,subKeys[cnt],48)

/*异或结果进入S盒,输出32位结果*/

DES_SBOX(copyRight)

/*P置换*/

DES_P_Transform(copyRight)

/*将明文左半部分与右半部分进行异或*/

DES_XOR(cipherBits,copyRight,32)

if(cnt != 0){

/*最终完成左右部的交换*/

DES_Swap(cipherBits,cipherBits+32)

}

}

/*逆初始置换(IP^1置换)*/

DES_IP_1_Transform(cipherBits)

Bit64ToChar8(cipherBits,plainBlock)

return 0

}

/*加密文件*/

int DES_Encrypt(char *plainFile, char *keyStr,char *cipherFile){

FILE *plain,*cipher

int count

ElemType plainBlock[8],cipherBlock[8],keyBlock[8]

ElemType bKey[64]

ElemType subKeys[16][48]

if((plain = fopen(plainFile,"rb")) == NULL){

return PLAIN_FILE_OPEN_ERROR

}

if((cipher = fopen(cipherFile,"wb")) == NULL){

return CIPHER_FILE_OPEN_ERROR

}

/*设置密钥*/

memcpy(keyBlock,keyStr,8)

/*将密钥转换为二进制流*/

Char8ToBit64(keyBlock,bKey)

/*生成子密钥*/

DES_MakeSubKeys(bKey,subKeys)

while(!feof(plain)){

/*每次读8个字节,并返回成功读取的字节数*/

if((count = fread(plainBlock,sizeof(char),8,plain)) == 8){

DES_EncryptBlock(plainBlock,subKeys,cipherBlock)

fwrite(cipherBlock,sizeof(char),8,cipher)

}

}

if(count){

/*填充*/

memset(plainBlock + count,'\0',7 - count)

/*最后一个字符保存包括最后一个字符在内的所填充的字符数量*/

plainBlock[7] = 8 - count

DES_EncryptBlock(plainBlock,subKeys,cipherBlock)

fwrite(cipherBlock,sizeof(char),8,cipher)

}

fclose(plain)

fclose(cipher)

return OK

}

/*解密文件*/

int DES_Decrypt(char *cipherFile, char *keyStr,char *plainFile){

FILE *plain, *cipher

int count,times = 0

long fileLen

ElemType plainBlock[8],cipherBlock[8],keyBlock[8]

ElemType bKey[64]

ElemType subKeys[16][48]

if((cipher = fopen(cipherFile,"rb")) == NULL){

return CIPHER_FILE_OPEN_ERROR

}

if((plain = fopen(plainFile,"wb")) == NULL){

return PLAIN_FILE_OPEN_ERROR

}

/*设置密钥*/

memcpy(keyBlock,keyStr,8)

/*将密钥转换为二进制流*/

Char8ToBit64(keyBlock,bKey)

/*生成子密钥*/

DES_MakeSubKeys(bKey,subKeys)

/*取文件长度 */

fseek(cipher,0,SEEK_END)/*将文件指针置尾*/

fileLen = ftell(cipher)/*取文件指针当前位置*/

rewind(cipher)/*将文件指针重指向文件头*/

while(1){

/*密文的字节数一定是8的整数倍*/

fread(cipherBlock,sizeof(char),8,cipher)

DES_DecryptBlock(cipherBlock,subKeys,plainBlock)

times += 8

if(times <fileLen){

fwrite(plainBlock,sizeof(char),8,plain)

}

else{

break

}

}

/*判断末尾是否被填充*/

if(plainBlock[7] <8){

for(count = 8 - plainBlock[7]count <7count++){

if(plainBlock[count] != '\0'){

break

}

}

}

if(count == 7){/*有填充*/

fwrite(plainBlock,sizeof(char),8 - plainBlock[7],plain)

}

else{/*无填充*/

fwrite(plainBlock,sizeof(char),8,plain)

}

fclose(plain)

fclose(cipher)

return OK

}

int main()

{

clock_t a,b

a = clock()

DES_Encrypt("1.txt","key.txt","2.txt")

b = clock()

printf("加密消耗%d毫秒\n",b-a)

system("pause")

a = clock()

DES_Decrypt("2.txt","key.txt","3.txt")

b = clock()

printf("解密消耗%d毫秒\n",b-a)

getchar()

return 0

}