AES加密算法之字节替换操作

来源：互联网发布：上海学声乐知乎编辑：程序博客网时间：2024/06/05 11:48

字节替换的基本原理：

使用一个表(被称为S盒)对分组进行逐一字节替换。S盒是AES算法定义的矩阵，把State中每个字节的高4位作为行值，低4位作为列值，然后取出S一盒中对应行列的元素作为输出。这个步骤提供了AES算法加密的非线性变换能力。S盒与有限域乘法逆元有关，具有良好的非线性特性。为了避免简单代数攻击，S盒结合了乘法逆元及可逆的仿射变换矩阵建构而成。

C语言实现过程直接使用S盒进行查表操作，附上字节替换（S盒）C语言源码：

#include <iostream>using namespace std;unsigned char sbox[]={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,  };void PrintMatrix(unsigned char m[4][4]){for(int i=0;i<4;i++){for(int j=0;j<4;j++){printf("%4x",m[i][j]);if(j%4==3)puts("");}}}void SubByte(unsigned char state[][4]){for(int i=0;i<4;i++){for(int j=0;j<4;j++){state[i][j]=sbox[state[i][j]];      //S盒查表操作}}}int main(){unsigned char state[4][4]={0,4,8,12,1,5,9,13,2,6,10,14,3,7,11,15,};printf("明文为:\n");PrintMatrix(state);SubByte(state);            //调用SubByte函数printf("经过S盒后输出:\n");PrintMatrix(state);return 0;}

程序运行结果如下：

1 0