概述
在密码学中，加密算法被分为两种主要类型：单向加密和双向加密。单向加密算法是不可逆的，主要用于数据完整性验证和密码存储，其中包括MD5、SHA等摘要算法。双向加密算法允许加密和解密过程，分为对称加密和非对称加密。对称加密使用相同的密钥进行加密和解密，包括AES加密、DES加密等；而非对称加密则使用公钥和私钥进行加密和解密。
AES（Advanced Encryption Standard）是一种高级加密标准，也称为Rijndael加密法。它是美国联邦政府采用的一种区块加密标准，旨在取代原先的DES。目前，AES已经被全世界广泛应用，成为对称密钥加密中最受欢迎的算法之一。AES支持三种不同长度的密钥：128位、192位和256位，这使得它在安全性和灵活性方面具有优势。
原理
-
密钥： 密钥是AES算法实现加密和解密的基础。对称加密算法之所以称为对称，是因为加密和解密过程都需要使用相同的密钥。AES支持三种不同长度的密钥：128位、192位和256位。常见的术语如AES128、AES192和AES256实际上指的就是AES算法使用不同长度密钥的变体。
-
填充： 为了理解填充的概念，需要先了解AES的分组加密特性。AES算法将明文分割成一个个独立的块，每个块的长度为128位（16字节）。这些明文块经过AES加密器进行处理后生成独立的密文块，最终组合在一起形成最终的加密结果。如果明文长度不是128位的整数倍，就需要对最后一个明文块进行填充以满足128位的要求。常见的填充模式有：
填充（Padding）是在加密过程中为了使数据达到特定长度而向数据末尾添加额外字节的过程。在AES加密中，有三种常见的填充模式： -
NoPadding：
- 不进行任何填充，但要求明文长度必须是16字节（128位）的整数倍。如果明文长度不是16字节的整数倍，则会抛出错误。
-
PKCS5Padding（默认）：
- 如果明文块长度少于16个字节（128位），则在明文块末尾补足相应数量的字节，使明文长度达到16字节，并且每个字节的值等于缺少的字节数。例如，如果明文为{1,2,3,4,5,a,b,c,d,e}，缺少6个字节，则补全为{1,2,3,4,5,a,b,c,d,e,6,6,6,6,6,6}。
-
ISO10126Padding：
- 如果明文块长度少于16个字节（128位），则在明文块末尾补足相应数量的字节，其中最后一个字节的值等于缺少的字节数，而其他字节填充随机数。例如，如果明文为{1,2,3,4,5,a,b,c,d,e}，缺少6个字节，则可能补全为{1,2,3,4,5,a,b,c,d,e,5,c,3,G,$,6}。
算法流程
-
字节替代（SubBytes）：
- 通过一个S盒（S-Box）进行替换，将输入的每个字节替换为另一个预定义的字节，实现非线性混淆。
-
行移位（ShiftRows）：
- 对每一行进行循环移位操作，第一行保持不变，第二行向左移动一个字节，第三行向左移动两个字节，第四行向左移动三个字节。
-
列混淆（MixColumns）：
- 将每一列看作一个多项式，通过乘以一个固定的矩阵来进行列混淆，从而增加加密的复杂性。
-
轮密钥加（AddRoundKey）：
- 将当前轮的状态矩阵与对应的轮密钥进行按位异或（XOR）操作，轮密钥是由种子密钥经过密钥扩展算法生成的。
这些操作在加密和解密过程中都会被执行。解密算法的每个步骤都是加密算法步骤的逆操作，并且加密和解密的操作顺序完全相反。这种设计保证了算法的正确性和安全性。加密和解密中的每一轮都会使用不同的轮密钥，而明文、密文和轮密钥都以一个4x4的矩阵表示。
代码实现
AES-256 密钥长度为 256 位，提供了极高的安全性。由于其密钥长度更长，因此具有更大的密钥空间，从而增加了破解的难度，即使是通过蛮力攻击也是很不好破解。
下表显示了不同 AES 密钥长度的可能组合随着密钥大小的增加而指数增加的情况：
可以看出，随着密钥长度的增加，可能的按键组合数量呈指数增加。
下面的代码实现了AES-256的加密与解密：
#include "string.h"
#include "AES.h"
AES::AES(unsigned char* key)
{
unsigned char sBox[] =
{ /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
0x63,0x7c,0x77,0x7b,0xf2,0x6b,0x6f,0xc5,0x30,0x01,0x67,0x2b,0xfe,0xd7,0xab,0x76, /*0*/
0xca,0x82,0xc9,0x7d,0xfa,0x59,0x47,0xf0,0xad,0xd4,0xa2,0xaf,0x9c,0xa4,0x72,0xc0, /*1*/
0xb7,0xfd,0x93,0x26,0x36,0x3f,0xf7,0xcc,0x34,0xa5,0xe5,0xf1,0x71,0xd8,0x31,0x15, /*2*/
0x04,0xc7,0x23,0xc3,0x18,0x96,0x05,0x9a,0x07,0x12,0x80,0xe2,0xeb,0x27,0xb2,0x75, /*3*/
0x09,0x83,0x2c,0x1a,0x1b,0x6e,0x5a,0xa0,0x52,0x3b,0xd6,0xb3,0x29,0xe3,0x2f,0x84, /*4*/
0x53,0xd1,0x00,0xed,0x20,0xfc,0xb1,0x5b,0x6a,0xcb,0xbe,0x39,0x4a,0x4c,0x58,0xcf, /*5*/
0xd0,0xef,0xaa,0xfb,0x43,0x4d,0x33,0x85,0x45,0xf9,0x02,0x7f,0x50,0x3c,0x9f,0xa8, /*6*/
0x51,0xa3,0x40,0x8f,0x92,0x9d,0x38,0xf5,0xbc,0xb6,0xda,0x21,0x10,0xff,0xf3,0xd2, /*7*/
0xcd,0x0c,0x13,0xec,0x5f,0x97,0x44,0x17,0xc4,0xa7,0x7e,0x3d,0x64,0x5d,0x19,0x73, /*8*/
0x60,0x81,0x4f,0xdc,0x22,0x2a,0x90,0x88,0x46,0xee,0xb8,0x14,0xde,0x5e,0x0b,0xdb, /*9*/
0xe0,0x32,0x3a,0x0a,0x49,0x06,0x24,0x5c,0xc2,0xd3,0xac,0x62,0x91,0x95,0xe4,0x79, /*a*/
0xe7,0xc8,0x37,0x6d,0x8d,0xd5,0x4e,0xa9,0x6c,0x56,0xf4,0xea,0x65,0x7a,0xae,0x08, /*b*/
0xba,0x78,0x25,0x2e,0x1c,0xa6,0xb4,0xc6,0xe8,0xdd,0x74,0x1f,0x4b,0xbd,0x8b,0x8a, /*c*/
0x70,0x3e,0xb5,0x66,0x48,0x03,0xf6,0x0e,0x61,0x35,0x57,0xb9,0x86,0xc1,0x1d,0x9e, /*d*/
0xe1,0xf8,0x98,0x11,0x69,0xd9,0x8e,0x94,0x9b,0x1e,0x87,0xe9,0xce,0x55,0x28,0xdf, /*e*/
0x8c,0xa1,0x89,0x0d,0xbf,0xe6,0x42,0x68,0x41,0x99,0x2d,0x0f,0xb0,0x54,0xbb,0x16 /*f*/
};
unsigned char invsBox[256] =
{ /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
0x52,0x09,0x6a,0xd5,0x30,0x36,0xa5,0x38,0xbf,0x40,0xa3,0x9e,0x81,0xf3,0xd7,0xfb, /*0*/
0x7c,0xe3,0x39,0x82,0x9b,0x2f,0xff,0x87,0x34,0x8e,0x43,0x44,0xc4,0xde,0xe9,0xcb, /*1*/
0x54,0x7b,0x94,0x32,0xa6,0xc2,0x23,0x3d,0xee,0x4c,0x95,0x0b,0x42,0xfa,0xc3,0x4e, /*2*/
0x08,0x2e,0xa1,0x66,0x28,0xd9,0x24,0xb2,0x76,0x5b,0xa2,0x49,0x6d,0x8b,0xd1,0x25, /*3*/
0x72,0xf8,0xf6,0x64,0x86,0x68,0x98,0x16,0xd4,0xa4,0x5c,0xcc,0x5d,0x65,0xb6,0x92, /*4*/
0x6c,0x70,0x48,0x50,0xfd,0xed,0xb9,0xda,0x5e,0x15,0x46,0x57,0xa7,0x8d,0x9d,0x84, /*5*/
0x90,0xd8,0xab,0x00,0x8c,0xbc,0xd3,0x0a,0xf7,0xe4,0x58,0x05,0xb8,0xb3,0x45,0x06, /*6*/
0xd0,0x2c,0x1e,0x8f,0xca,0x3f,0x0f,0x02,0xc1,0xaf,0xbd,0x03,0x01,0x13,0x8a,0x6b, /*7*/
0x3a,0x91,0x11,0x41,0x4f,0x67,0xdc,0xea,0x97,0xf2,0xcf,0xce,0xf0,0xb4,0xe6,0x73, /*8*/
0x96,0xac,0x74,0x22,0xe7,0xad,0x35,0x85,0xe2,0xf9,0x37,0xe8,0x1c,0x75,0xdf,0x6e, /*9*/
0x47,0xf1,0x1a,0x71,0x1d,0x29,0xc5,0x89,0x6f,0xb7,0x62,0x0e,0xaa,0x18,0xbe,0x1b, /*a*/
0xfc,0x56,0x3e,0x4b,0xc6,0xd2,0x79,0x20,0x9a,0xdb,0xc0,0xfe,0x78,0xcd,0x5a,0xf4, /*b*/
0x1f,0xdd,0xa8,0x33,0x88,0x07,0xc7,0x31,0xb1,0x12,0x10,0x59,0x27,0x80,0xec,0x5f, /*c*/
0x60,0x51,0x7f,0xa9,0x19,0xb5,0x4a,0x0d,0x2d,0xe5,0x7a,0x9f,0x93,0xc9,0x9c,0xef, /*d*/
0xa0,0xe0,0x3b,0x4d,0xae,0x2a,0xf5,0xb0,0xc8,0xeb,0xbb,0x3c,0x83,0x53,0x99,0x61, /*e*/
0x17,0x2b,0x04,0x7e,0xba,0x77,0xd6,0x26,0xe1,0x69,0x14,0x63,0x55,0x21,0x0c,0x7d /*f*/
};
memcpy(Sbox, sBox, 256);
memcpy(InvSbox, invsBox, 256);
KeyExpansion(key, w);
}
AES::~AES()
{
}
unsigned char* AES::Cipher(unsigned char* input)
{
unsigned char state[4][4];
int i,r,c;
for(r=0; r<4; r++)
{
for(c=0; c<4 ;c++)
{
state[r][c] = input[c*4+r];
}
}
AddRoundKey(state,w[0]);
for(i=1; i<=10; i++)
{
SubBytes(state);
ShiftRows(state);
if(i!=10)MixColumns(state);
AddRoundKey(state,w[i]);
}
for(r=0; r<4; r++)
{
for(c=0; c<4 ;c++)
{
input[c*4+r] = state[r][c];
}
}
return input;
}
unsigned char* AES::InvCipher(unsigned char* input)
{
unsigned char state[4][4];
int i,r,c;
for(r=0; r<4; r++)
{
for(c=0; c<4 ;c++)
{
state[r][c] = input[c*4+r];
}
}
AddRoundKey(state, w[10]);
for(i=9; i>=0; i--)
{
InvShiftRows(state);
InvSubBytes(state);
AddRoundKey(state, w[i]);
if(i)
{
InvMixColumns(state);
}
}
for(r=0; r<4; r++)
{
for(c=0; c<4 ;c++)
{
input[c*4+r] = state[r][c];
}
}
return input;
}
void* AES::Cipher(void* input, int length)
{
unsigned char* in = (unsigned char*) input;
int i;
if(!length)
{
while(*(in+length++));
in = (unsigned char*) input;
}
for(i=0; i<length; i+=16)
{
Cipher(in+i);
}
return input;
}
void* AES::InvCipher(void* input, int length)
{
unsigned char* in = (unsigned char*) input;
int i;
for(i=0; i<length; i+=16)
{
InvCipher(in+i);
}
return input;
}
void AES::KeyExpansion(unsigned char* key, unsigned char w[][4][4])
{
int i,j,r,c;
unsigned char rc[] = {0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36};
for(r=0; r<4; r++)
{
for(c=0; c<4; c++)
{
w[0][r][c] = key[r+c*4];
}
}
for(i=1; i<=10; i++)
{
for(j=0; j<4; j++)
{
unsigned char t[4];
for(r=0; r<4; r++)
{
t[r] = j ? w[i][r][j-1] : w[i-1][r][3];
}
if(j == 0)
{
unsigned char temp = t[0];
for(r=0; r<3; r++)
{
t[r] = Sbox[t[(r+1)%4]];
}
t[3] = Sbox[temp];
t[0] ^= rc[i-1];
}
for(r=0; r<4; r++)
{
w[i][r][j] = w[i-1][r][j] ^ t[r];
}
}
}
}
unsigned char AES::FFmul(unsigned char a, unsigned char b)
{
unsigned char bw[4];
unsigned char res=0;
int i;
bw[0] = b;
for(i=1; i<4; i++)
{
bw[i] = bw[i-1]<<1;
if(bw[i-1]&0x80)
{
bw[i]^=0x1b;
}
}
for(i=0; i<4; i++)
{
if((a>>i)&0x01)
{
res ^= bw[i];
}
}
return res;
}
void AES::SubBytes(unsigned char state[][4])
{
int r,c;
for(r=0; r<4; r++)
{
for(c=0; c<4; c++)
{
state[r][c] = Sbox[state[r][c]];
}
}
}
void AES::ShiftRows(unsigned char state[][4])
{
unsigned char t[4];
int r,c;
for(r=1; r<4; r++)
{
for(c=0; c<4; c++)
{
t[c] = state[r][(c+r)%4];
}
for(c=0; c<4; c++)
{
state[r][c] = t[c];
}
}
}
void AES::MixColumns(unsigned char state[][4])
{
unsigned char t[4];
int r,c;
for(c=0; c< 4; c++)
{
for(r=0; r<4; r++)
{
t[r] = state[r][c];
}
for(r=0; r<4; r++)
{
state[r][c] = FFmul(0x02, t[r])
^ FFmul(0x03, t[(r+1)%4])
^ FFmul(0x01, t[(r+2)%4])
^ FFmul(0x01, t[(r+3)%4]);
}
}
}
void AES::AddRoundKey(unsigned char state[][4], unsigned char k[][4])
{
int r,c;
for(c=0; c<4; c++)
{
for(r=0; r<4; r++)
{
state[r][c] ^= k[r][c];
}
}
}
void AES::InvSubBytes(unsigned char state[][4])
{
int r,c;
for(r=0; r<4; r++)
{
for(c=0; c<4; c++)
{
state[r][c] = InvSbox[state[r][c]];
}
}
}
void AES::InvShiftRows(unsigned char state[][4])
{
unsigned char t[4];
int r,c;
for(r=1; r<4; r++)
{
for(c=0; c<4; c++)
{
t[c] = state[r][(c-r+4)%4];
}
for(c=0; c<4; c++)
{
state[r][c] = t[c];
}
}
}
void AES::InvMixColumns(unsigned char state[][4])
{
unsigned char t[4];
int r,c;
for(c=0; c< 4; c++)
{
for(r=0; r<4; r++)
{
t[r] = state[r][c];
}
for(r=0; r<4; r++)
{
state[r][c] = FFmul(0x0e, t[r])
^ FFmul(0x0b, t[(r+1)%4])
^ FFmul(0x0d, t[(r+2)%4])
^ FFmul(0x09, t[(r+3)%4]);
}
}
}
解密代码：
#include "DeAesCode.h"
DeAesCode::DeAesCode(unsigned char* key)
{
unsigned char sBox[] =
{ /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
0x63,0x7c,0x77,0x7b,0xf2,0x6b,0x6f,0xc5,0x30,0x01,0x67,0x2b,0xfe,0xd7,0xab,0x76, /*0*/
0xca,0x82,0xc9,0x7d,0xfa,0x59,0x47,0xf0,0xad,0xd4,0xa2,0xaf,0x9c,0xa4,0x72,0xc0, /*1*/
0xb7,0xfd,0x93,0x26,0x36,0x3f,0xf7,0xcc,0x34,0xa5,0xe5,0xf1,0x71,0xd8,0x31,0x15, /*2*/
0x04,0xc7,0x23,0xc3,0x18,0x96,0x05,0x9a,0x07,0x12,0x80,0xe2,0xeb,0x27,0xb2,0x75, /*3*/
0x09,0x83,0x2c,0x1a,0x1b,0x6e,0x5a,0xa0,0x52,0x3b,0xd6,0xb3,0x29,0xe3,0x2f,0x84, /*4*/
0x53,0xd1,0x00,0xed,0x20,0xfc,0xb1,0x5b,0x6a,0xcb,0xbe,0x39,0x4a,0x4c,0x58,0xcf, /*5*/
0xd0,0xef,0xaa,0xfb,0x43,0x4d,0x33,0x85,0x45,0xf9,0x02,0x7f,0x50,0x3c,0x9f,0xa8, /*6*/
0x51,0xa3,0x40,0x8f,0x92,0x9d,0x38,0xf5,0xbc,0xb6,0xda,0x21,0x10,0xff,0xf3,0xd2, /*7*/
0xcd,0x0c,0x13,0xec,0x5f,0x97,0x44,0x17,0xc4,0xa7,0x7e,0x3d,0x64,0x5d,0x19,0x73, /*8*/
0x60,0x81,0x4f,0xdc,0x22,0x2a,0x90,0x88,0x46,0xee,0xb8,0x14,0xde,0x5e,0x0b,0xdb, /*9*/
0xe0,0x32,0x3a,0x0a,0x49,0x06,0x24,0x5c,0xc2,0xd3,0xac,0x62,0x91,0x95,0xe4,0x79, /*a*/
0xe7,0xc8,0x37,0x6d,0x8d,0xd5,0x4e,0xa9,0x6c,0x56,0xf4,0xea,0x65,0x7a,0xae,0x08, /*b*/
0xba,0x78,0x25,0x2e,0x1c,0xa6,0xb4,0xc6,0xe8,0xdd,0x74,0x1f,0x4b,0xbd,0x8b,0x8a, /*c*/
0x70,0x3e,0xb5,0x66,0x48,0x03,0xf6,0x0e,0x61,0x35,0x57,0xb9,0x86,0xc1,0x1d,0x9e, /*d*/
0xe1,0xf8,0x98,0x11,0x69,0xd9,0x8e,0x94,0x9b,0x1e,0x87,0xe9,0xce,0x55,0x28,0xdf, /*e*/
0x8c,0xa1,0x89,0x0d,0xbf,0xe6,0x42,0x68,0x41,0x99,0x2d,0x0f,0xb0,0x54,0xbb,0x16 /*f*/
};
unsigned char invsBox[256] =
{ /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
0x52,0x09,0x6a,0xd5,0x30,0x36,0xa5,0x38,0xbf,0x40,0xa3,0x9e,0x81,0xf3,0xd7,0xfb, /*0*/
0x7c,0xe3,0x39,0x82,0x9b,0x2f,0xff,0x87,0x34,0x8e,0x43,0x44,0xc4,0xde,0xe9,0xcb, /*1*/
0x54,0x7b,0x94,0x32,0xa6,0xc2,0x23,0x3d,0xee,0x4c,0x95,0x0b,0x42,0xfa,0xc3,0x4e, /*2*/
0x08,0x2e,0xa1,0x66,0x28,0xd9,0x24,0xb2,0x76,0x5b,0xa2,0x49,0x6d,0x8b,0xd1,0x25, /*3*/
0x72,0xf8,0xf6,0x64,0x86,0x68,0x98,0x16,0xd4,0xa4,0x5c,0xcc,0x5d,0x65,0xb6,0x92, /*4*/
0x6c,0x70,0x48,0x50,0xfd,0xed,0xb9,0xda,0x5e,0x15,0x46,0x57,0xa7,0x8d,0x9d,0x84, /*5*/
0x90,0xd8,0xab,0x00,0x8c,0xbc,0xd3,0x0a,0xf7,0xe4,0x58,0x05,0xb8,0xb3,0x45,0x06, /*6*/
0xd0,0x2c,0x1e,0x8f,0xca,0x3f,0x0f,0x02,0xc1,0xaf,0xbd,0x03,0x01,0x13,0x8a,0x6b, /*7*/
0x3a,0x91,0x11,0x41,0x4f,0x67,0xdc,0xea,0x97,0xf2,0xcf,0xce,0xf0,0xb4,0xe6,0x73, /*8*/
0x96,0xac,0x74,0x22,0xe7,0xad,0x35,0x85,0xe2,0xf9,0x37,0xe8,0x1c,0x75,0xdf,0x6e, /*9*/
0x47,0xf1,0x1a,0x71,0x1d,0x29,0xc5,0x89,0x6f,0xb7,0x62,0x0e,0xaa,0x18,0xbe,0x1b, /*a*/
0xfc,0x56,0x3e,0x4b,0xc6,0xd2,0x79,0x20,0x9a,0xdb,0xc0,0xfe,0x78,0xcd,0x5a,0xf4, /*b*/
0x1f,0xdd,0xa8,0x33,0x88,0x07,0xc7,0x31,0xb1,0x12,0x10,0x59,0x27,0x80,0xec,0x5f, /*c*/
0x60,0x51,0x7f,0xa9,0x19,0xb5,0x4a,0x0d,0x2d,0xe5,0x7a,0x9f,0x93,0xc9,0x9c,0xef, /*d*/
0xa0,0xe0,0x3b,0x4d,0xae,0x2a,0xf5,0xb0,0xc8,0xeb,0xbb,0x3c,0x83,0x53,0x99,0x61, /*e*/
0x17,0x2b,0x04,0x7e,0xba,0x77,0xd6,0x26,0xe1,0x69,0x14,0x63,0x55,0x21,0x0c,0x7d /*f*/
};
memcpy(Sbox, sBox, 256);
memcpy(InvSbox, invsBox, 256);
KeyExpansion(key, w);
}
DeAesCode::~DeAesCode()
{
}
unsigned char* DeAesCode::Cipher(unsigned char* input)
{
unsigned char state[4][4];
int i, r, c;
for (r = 0; r<4; r++)
{
for (c = 0; c<4; c++)
{
state[r][c] = input[c * 4 + r];
}
}
AddRoundKey(state, w[0]);
for (i = 1; i <= 10; i++)
{
SubBytes(state);
ShiftRows(state);
if (i != 10)MixColumns(state);
AddRoundKey(state, w[i]);
}
for (r = 0; r<4; r++)
{
for (c = 0; c<4; c++)
{
input[c * 4 + r] = state[r][c];
}
}
return input;
}
unsigned char* DeAesCode::InvCipher(unsigned char* input)
{
unsigned char state[4][4];
int i, r, c;
for (r = 0; r<4; r++)
{
for (c = 0; c<4; c++)
{
state[r][c] = input[c * 4 + r];
}
}
AddRoundKey(state, w[10]);
for (i = 9; i >= 0; i--)
{
InvShiftRows(state);
InvSubBytes(state);
AddRoundKey(state, w[i]);
if (i)
{
InvMixColumns(state);
}
}
for (r = 0; r<4; r++)
{
for (c = 0; c<4; c++)
{
input[c * 4 + r] = state[r][c];
}
}
return input;
}
void* DeAesCode::Cipher(void* input, int length)
{
unsigned char* in = (unsigned char*)input;
int i;
if (!length)
{
while (*(in + length++));
in = (unsigned char*)input;
}
for (i = 0; i<length; i += 16)
{
Cipher(in + i);
}
return input;
}
void* DeAesCode::InvCipher(void* input, int length)
{
unsigned char* in = (unsigned char*)input;
int i;
for (i = 0; i<length; i += 16)
{
InvCipher(in + i);
}
return input;
}
void DeAesCode::KeyExpansion(unsigned char* key, unsigned char w[][4][4])
{
int i, j, r, c;
unsigned char rc[] = { 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36 };
for (r = 0; r<4; r++)
{
for (c = 0; c<4; c++)
{
w[0][r][c] = key[r + c * 4];
}
}
for (i = 1; i <= 10; i++)
{
for (j = 0; j<4; j++)
{
unsigned char t[4];
for (r = 0; r<4; r++)
{
t[r] = j ? w[i][r][j - 1] : w[i - 1][r][3];
}
if (j == 0)
{
unsigned char temp = t[0];
for (r = 0; r<3; r++)
{
t[r] = Sbox[t[(r + 1) % 4]];
}
t[3] = Sbox[temp];
t[0] ^= rc[i - 1];
}
for (r = 0; r<4; r++)
{
w[i][r][j] = w[i - 1][r][j] ^ t[r];
}
}
}
}
unsigned char DeAesCode::FFmul(unsigned char a, unsigned char b)
{
unsigned char bw[4];
unsigned char res = 0;
int i;
bw[0] = b;
for (i = 1; i<4; i++)
{
bw[i] = bw[i - 1] << 1;
if (bw[i - 1] & 0x80)
{
bw[i] ^= 0x1b;
}
}
for (i = 0; i<4; i++)
{
if ((a >> i) & 0x01)
{
res ^= bw[i];
}
}
return res;
}
void DeAesCode::SubBytes(unsigned char state[][4])
{
int r, c;
for (r = 0; r<4; r++)
{
for (c = 0; c<4; c++)
{
state[r][c] = Sbox[state[r][c]];
}
}
}
void DeAesCode::ShiftRows(unsigned char state[][4])
{
unsigned char t[4];
int r, c;
for (r = 1; r<4; r++)
{
for (c = 0; c<4; c++)
{
t[c] = state[r][(c + r) % 4];
}
for (c = 0; c<4; c++)
{
state[r][c] = t[c];
}
}
}
void DeAesCode::MixColumns(unsigned char state[][4])
{
unsigned char t[4];
int r, c;
for (c = 0; c< 4; c++)
{
for (r = 0; r<4; r++)
{
t[r] = state[r][c];
}
for (r = 0; r<4; r++)
{
state[r][c] = FFmul(0x02, t[r])
^ FFmul(0x03, t[(r + 1) % 4])
^ FFmul(0x01, t[(r + 2) % 4])
^ FFmul(0x01, t[(r + 3) % 4]);
}
}
}
void DeAesCode::AddRoundKey(unsigned char state[][4], unsigned char k[][4])
{
int r, c;
for (c = 0; c<4; c++)
{
for (r = 0; r<4; r++)
{
state[r][c] ^= k[r][c];
}
}
}
void DeAesCode::InvSubBytes(unsigned char state[][4])
{
int r, c;
for (r = 0; r<4; r++)
{
for (c = 0; c<4; c++)
{
state[r][c] = InvSbox[state[r][c]];
}
}
}
void DeAesCode::InvShiftRows(unsigned char state[][4])
{
unsigned char t[4];
int r, c;
for (r = 1; r<4; r++)
{
for (c = 0; c<4; c++)
{
t[c] = state[r][(c - r + 4) % 4];
}
for (c = 0; c<4; c++)
{
state[r][c] = t[c];
}
}
}
void DeAesCode::InvMixColumns(unsigned char state[][4])
{
unsigned char t[4];
int r, c;
for (c = 0; c< 4; c++)
{
for (r = 0; r<4; r++)
{
t[r] = state[r][c];
}
for (r = 0; r<4; r++)
{
state[r][c] = FFmul(0x0e, t[r])
^ FFmul(0x0b, t[(r + 1) % 4])
^ FFmul(0x0d, t[(r + 2) % 4])
^ FFmul(0x09, t[(r + 3) % 4]);
}
}
}
代码调用测试：
#include "AES.h"
#include <string.h>
#include "DeAesCode.h"
void print(unsigned char* state);
int main(int argc, char* argv[])
{
unsigned char key[] =
{
0x2b, 0x7e, 0x15, 0x16,
0x28, 0xae, 0xd2, 0xa6,
0xab, 0xf7, 0x15, 0x88,
0x09, 0xcf, 0x4f, 0x3c
};
AES aes(key);
DeAesCode deace(key);
char str[] = "Hello, World!";
int l = strlen(str);
printf("输入:");
printf(str);
printf("\n加密后:");
aes.Cipher((void *)str);
for (int j = 0; j < l; j++)
{
printf("%X ", (unsigned char)str[j]);
}
printf("\n");
printf("密文：");
printf(str);
deace.InvCipher((void *)str,21);
printf("\n解密后:");
for (int j = 0; j < l; j++)
{
printf("%X ", (unsigned char)str[j]);
}
printf("\n");
printf(str);
return 0;
}
void print(unsigned char* state)
{
int i;
for(i=0; i<16; i++)
{
printf("%s%X ",state[i]>15 ? "" : "0", state[i]);
}
printf("\n");
}
源码下载地址：https://download.csdn.net/download/matt45m/88932923?spm=1001.2014.3001.5503