AES加解密算法Qt实现

【声明】

(1) 本文源码

在一位未署名网友源码基础上，利用Qt编程，实现了AES加解密算法，并添加了文件加解密功能。在此表示感谢！该源码仅供学习交流，请勿用于商业目的。

(2) 图片及描述

除图1外，图片及部分解析来自http://zh.wikipedia.org/wiki/%E9%AB%98%E7%BA%A7%E5%8A%A0%E5%AF%86%E6%A0%87%E5%87%86。图1为个人劳动成果，请勿盗用此图。

【简介】

AES（Advanced Encryption Standard，高级加密标准），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。

【算法描述】

AES的区块长度固定为128 比特，密钥长度则可以是128，192或256比特。AES加密过程是在一个4×4的字节矩阵上运作，这个矩阵又称为“体（state）”，其初值就是一个明文区块（矩阵中一个元素大小就是明文区块中的一个Byte）。加密时，各轮AES加密循环（除最后一轮外）均包含4个步骤： 1.AddRoundKey — 矩阵中的每一个字节都与该次轮密钥（round key）做XOR运算；每个子密钥由密钥生成方案产生。 2.SubBytes — 通过一个非线性的替换函数，用查找表的方式把每个字节替换成对应的字节。 3.ShiftRows — 将矩阵中的每个横列进行循环式移位。 4.MixColumns — 为了充分混合矩阵中各个直行的操作。这个步骤使用线性转换来混合每内联的四个字节。最后一个加密循环中省略MixColumns步骤，而以另一个AddRoundKey取代。 AES算法加解密流程如图1所示：

AES加解密算法Qt实现

图1 AES加密算法流程图

【算法解析】

1 常量定义

S-Box

const unsigned char AES::Sbox[16*16]=
{// populate the Sbox matrix
/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
/*0*/ 0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
/*1*/ 0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
/*2*/ 0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
/*3*/ 0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
/*4*/ 0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
/*5*/ 0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
/*6*/ 0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
/*7*/ 0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
/*8*/ 0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
/*9*/ 0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
/*a*/ 0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
/*b*/ 0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
/*c*/ 0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
/*d*/ 0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
/*e*/ 0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
/*f*/ 0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16
};

const unsigned char AES::Sbox[16*16]=

{// populate the Sbox matrix

 /* 0     1     2     3     4     5     6     7     8     9     a     b     c     d     e     f */

 /*0*/  0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,

 /*1*/  0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,

 /*2*/  0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,

 /*3*/  0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,

 /*4*/  0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,

 /*5*/  0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,

 /*6*/  0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,

 /*7*/  0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,

 /*8*/  0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,

 /*9*/  0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,

 /*a*/  0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,

 /*b*/  0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,

 /*c*/  0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,

 /*d*/  0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,

 /*e*/  0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,

 /*f*/  0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16

};

const unsigned char AES::iSbox[16*16]=
{
// populate the iSbox matrix
/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
/*0*/ 0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
/*1*/ 0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
/*2*/ 0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
/*3*/ 0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,
/*4*/ 0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,
/*5*/ 0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
/*6*/ 0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,
/*7*/ 0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,
/*8*/ 0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
/*9*/ 0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,
/*a*/ 0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
/*b*/ 0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
/*c*/ 0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,
/*d*/ 0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,
/*e*/ 0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
/*f*/ 0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d
};

const unsigned char AES::iSbox[16*16]=

{

    // populate the iSbox matrix

    /* 0     1     2     3     4     5     6     7     8     9     a     b     c     d     e     f */

    /*0*/  0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,

    /*1*/  0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,

    /*2*/  0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,

    /*3*/  0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,

    /*4*/  0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,

    /*5*/  0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,

    /*6*/  0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,

    /*7*/  0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,

    /*8*/  0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,

    /*9*/  0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,

    /*a*/  0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,

    /*b*/  0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,

    /*c*/  0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,

    /*d*/  0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,

    /*e*/  0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,

    /*f*/  0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d

};

Rcon

const unsigned char AES::Rcon[11*4]=
{
0x00, 0x00, 0x00, 0x00,
0x01, 0x00, 0x00, 0x00,
0x02, 0x00, 0x00, 0x00,
0x04, 0x00, 0x00, 0x00,
0x08, 0x00, 0x00, 0x00,
0x10, 0x00, 0x00, 0x00,
0x20, 0x00, 0x00, 0x00,
0x40, 0x00, 0x00, 0x00,
0x80, 0x00, 0x00, 0x00,
0x1b, 0x00, 0x00, 0x00,
0x36, 0x00, 0x00, 0x00
};

const unsigned char AES::Rcon[11*4]=

{

    0x00, 0x00, 0x00, 0x00,

    0x01, 0x00, 0x00, 0x00,

    0x02, 0x00, 0x00, 0x00,

    0x04, 0x00, 0x00, 0x00,

    0x08, 0x00, 0x00, 0x00,

    0x10, 0x00, 0x00, 0x00,

    0x20, 0x00, 0x00, 0x00,

    0x40, 0x00, 0x00, 0x00,

    0x80, 0x00, 0x00, 0x00,

    0x1b, 0x00, 0x00, 0x00,

    0x36, 0x00, 0x00, 0x00

};

2 密钥扩展（Expand Key） AES算法利用外部输入密钥Key(又称为基密钥，密钥串的字数为Nk)，通过密钥扩展可得到共4(Nk+1)字的扩展密钥w[4× (Nr+1)]，其中Nr为数据分组密钥的轮数。密钥扩展主要包括3个步骤： (1) 位置变换RotWord() 把一个4字节的基密钥序列[a0，a1，a2，a3]，左移一个字节变为[a1，a2，a3，a0]。

void AES::RotWord(unsigned char * word,unsigned char *result)
{
result[0] = word[1];
result[1] = word[2];
result[2] = word[3];
result[3] = word[0];
}

void AES::RotWord(unsigned char * word,unsigned char *result)

{

    result[0] = word[1];

    result[1] = word[2];

    result[2] = word[3];

    result[3] = word[0];

}

(2) SubWord() 对一个4字节的输入字[a0，a1，a2，a3]，每一个字节进行S盒变换。

void AES::SubWord(unsigned char * word,unsigned char* result)
{
result[0] = Sbox[ 16*(word[0] >> 4)+ (word[0] & 0x0f) ];
result[1] = Sbox[ 16*(word[1] >> 4)+ (word[1] & 0x0f) ];
result[2] = Sbox[ 16*(word[2] >> 4)+ (word[2] & 0x0f) ];
result[3] = Sbox[ 16*(word[3] >> 4)+ (word[3] & 0x0f) ];
}

void AES::SubWord(unsigned char * word,unsigned char* result)

{

    result[0] =  Sbox[ 16*(word[0] >> 4)+ (word[0] & 0x0f) ];

    result[1] =  Sbox[ 16*(word[1] >> 4)+ (word[1] & 0x0f) ];

    result[2] =  Sbox[ 16*(word[2] >> 4)+ (word[2] & 0x0f) ];

    result[3] =  Sbox[ 16*(word[3] >> 4)+ (word[3] & 0x0f) ];

}

(3) 变换Rcon[] Rcon[i]表示32比特字符串[x^i-1，00，00，00]。

temp[0] = (byte)( (int)temp[0] ^ (int) Rcon[4*(row/Nk)+0] );
temp[1] = (byte)( (int)temp[1] ^ (int) Rcon[4*(row/Nk)+1] );
temp[2] = (byte)( (int)temp[2] ^ (int) Rcon[4*(row/Nk)+2] );
temp[3] = (byte)( (int)temp[3] ^ (int) Rcon[4*(row/Nk)+3] );

temp[0] = (byte)( (int)temp[0] ^ (int) Rcon[4*(row/Nk)+0] );

temp[1] = (byte)( (int)temp[1] ^ (int) Rcon[4*(row/Nk)+1] );

temp[2] = (byte)( (int)temp[2] ^ (int) Rcon[4*(row/Nk)+2] );

temp[3] = (byte)( (int)temp[3] ^ (int) Rcon[4*(row/Nk)+3] );

扩展密钥的前Nk个字就是基密钥Key；以后的字w[i]等于它前一个字w[i-1]与前第Nk个字w[i-Nk]的异或，即w[i]=w[i-1] XOR w[i-Nk]。但如果i是Nk的倍数，则w[i]=w[i-Nk] XOR SubWord(RotWord(w[i-1])) XOR Rcon[i/Nk]。

void AES::KeyExpansion()
{
unsigned char result[4],result2[4];
memset(w,0,16*15);//没有根据key的位数进行开辟空间，直接开辟了最大空间
int row;
for (row = 0; row < Nk; row++)//Nk=4,6,8得到初始密码
{
w[4*row+0] = key[4*row];
w[4*row+1] = key[4*row+1];
w[4*row+2] = key[4*row+2];
w[4*row+3] = key[4*row+3];
}
unsigned char temp[4];
for (row = Nk; row < Nb * (Nr+1); row++)//产生密匙顺序表
{
temp[0] = w[4*(row-1)+0];
temp[1] = w[4*(row-1)+1];
temp[2] = w[4*(row-1)+2];
temp[3] = w[4*(row-1)+3];
if (row % Nk == 0)
{
RotWord(temp,result);
SubWord(result,result2);
memcpy(temp,result2,4);//
//RotWord 例程非常简单，它接受 4 字节的数组并将它们向左旋转位移 1 位。
//因为轮回次序表 w[] 有四列，所以 RotWord 会将一行 w[] 向左旋转位移.
//SubWord 例程使用置换表 Sbox，针对密钥次序表 w[] 的给定行执行逐字节置换。
temp[0] = (byte)( (int)temp[0] ^ (int) Rcon[4*(row/Nk)+0] );
temp[1] = (byte)( (int)temp[1] ^ (int) Rcon[4*(row/Nk)+1] );
temp[2] = (byte)( (int)temp[2] ^ (int) Rcon[4*(row/Nk)+2] );
temp[3] = (byte)( (int)temp[3] ^ (int) Rcon[4*(row/Nk)+3] );
}
else if ( Nk > 6 && (row % Nk == 4) )
{
SubWord(temp,result);
memcpy(temp,result,4);
}
// w[row] = w[row-Nk] xor temp
w[4*row+0] = (byte) ( (int) w[4*(row-Nk)+0] ^ (int)temp[0] );
w[4*row+1] = (byte) ( (int) w[4*(row-Nk)+1] ^ (int)temp[1] );
w[4*row+2] = (byte) ( (int) w[4*(row-Nk)+2] ^ (int)temp[2] );
w[4*row+3] = (byte) ( (int) w[4*(row-Nk)+3] ^ (int)temp[3] );
} // for loop
} // KeyExpansion()

void AES::KeyExpansion()

{

    unsigned char result[4],result2[4];

    memset(w,0,16*15);//没有根据key的位数进行开辟空间，直接开辟了最大空间

    int row;

    for (row = 0; row < Nk; row++)//Nk=4,6,8得到初始密码

    {

        w[4*row+0] =  key[4*row];

        w[4*row+1] =  key[4*row+1];

        w[4*row+2] =  key[4*row+2];

        w[4*row+3] =  key[4*row+3];

    }

    unsigned char temp[4];

    for (row = Nk; row < Nb * (Nr+1); row++)//产生密匙顺序表

    {

        temp[0] =  w[4*(row-1)+0];

        temp[1] =  w[4*(row-1)+1];

        temp[2] =  w[4*(row-1)+2];

        temp[3] =  w[4*(row-1)+3];

        if (row % Nk == 0)

        {

            RotWord(temp,result);

            SubWord(result,result2);

            memcpy(temp,result2,4);//

            //RotWord 例程非常简单，它接受 4 字节的数组并将它们向左旋转位移 1 位。

            //因为轮回次序表 w[] 有四列，所以 RotWord 会将一行 w[] 向左旋转位移.

            //SubWord 例程使用置换表 Sbox，针对密钥次序表 w[] 的给定行执行逐字节置换。

            temp[0] = (byte)( (int)temp[0] ^ (int) Rcon[4*(row/Nk)+0] );

            temp[1] = (byte)( (int)temp[1] ^ (int) Rcon[4*(row/Nk)+1] );

            temp[2] = (byte)( (int)temp[2] ^ (int) Rcon[4*(row/Nk)+2] );

            temp[3] = (byte)( (int)temp[3] ^ (int) Rcon[4*(row/Nk)+3] );

        }

        else if ( Nk > 6 && (row % Nk == 4) )

        {

            SubWord(temp,result);

            memcpy(temp,result,4);

        }

        // w[row] = w[row-Nk] xor temp

        w[4*row+0] = (byte) ( (int) w[4*(row-Nk)+0] ^ (int)temp[0] );

        w[4*row+1] = (byte) ( (int) w[4*(row-Nk)+1] ^ (int)temp[1] );

        w[4*row+2] = (byte) ( (int) w[4*(row-Nk)+2] ^ (int)temp[2] );

        w[4*row+3] = (byte) ( (int) w[4*(row-Nk)+3] ^ (int)temp[3] );

    }  // for loop

}  // KeyExpansion()

3 轮密钥加(Add Round Key) 如图2所示，经过扩展的密钥，根据加密的轮数用相应的扩展密钥的4个数据项和中间状态矩阵上的列进行按位异或：

[s(0,c)’, s(1,c)’, s(2,c)’, s(3,c)’]= [s(0,c), s(1,c), s(2,c), s(3,c)] XOR [W(round×Nb+c)]。

AES加解密算法Qt实现

图2 Add Round Key

void AES::AddRoundKey(int round)
{
int r,c;
for (r = 0; r < 4; r++)
{
for (c = 0; c < 4; c++)
{//w: 4*x+y
State[r][c]=(unsigned char)((int)State[r][c]^(int)w[4*((round*4)+c)+r]);
}
}
} // AddRoundKey()

void AES::AddRoundKey(int round)

{

    int r,c;

    for (r = 0; r < 4; r++)

    {

        for (c = 0; c < 4; c++)

        {//w:    4*x+y

            State[r][c]=(unsigned char)((int)State[r][c]^(int)w[4*((round*4)+c)+r]);

        }

    }

}  // AddRoundKey()

4 字节替代(Substitute Bytes) 如图3所示，从S-Box中找出S[A]=S[x,y]的值，其中A为输入矩阵任一元素。将

AES加解密算法Qt实现

转换为

AES加解密算法Qt实现

图3 Substitute Bytes

void AES::SubBytes()
{
int r,c;
for (r = 0; r < 4; r++)
{
for (c = 0; c < 4; c++)
{
State[r][c] = Sbox[ 16*(State[r][c] >> 4)+ ( State[r][c] & 0x0f) ];
}
}
} // SubBytes
void AES::InvSubBytes()
{
int r,c;
for (r = 0; r < 4; r++)
{
for (c = 0; c < 4; c++)
{
State[r][c] = iSbox[ 16*( State[r][c] >> 4)+( State[r][c] & 0x0f) ];
}
}
} // InvSubBytes

void AES::SubBytes()

{

    int r,c;

    for (r = 0; r < 4; r++)

    {

        for (c = 0; c < 4; c++)

        {

            State[r][c] =  Sbox[ 16*(State[r][c] >> 4)+ ( State[r][c] & 0x0f) ];

        }

    }

}  // SubBytes

void AES::InvSubBytes()

{

    int r,c;

    for (r = 0; r < 4; r++)

    {

        for (c = 0; c < 4; c++)

        {

            State[r][c] =  iSbox[ 16*( State[r][c] >> 4)+( State[r][c] & 0x0f) ];

        }

    }

}  // InvSubBytes

5 行移位(Shift Rows) 如图4所示，将矩阵中的每一个横列进行循环式移位。移位的规则是：第一行维持不变，第二、第三、第四行的每个字节向左循环移位的偏移量分别为1格，2格，3格。

AES加解密算法Qt实现

图4 Shift Rows

void AES::ShiftRows()
{
unsigned char temp[4*4];
int r,c;
for (r = 0; r < 4; r++) // copy State into temp[]
{
for (c = 0; c < 4; c++)
{
temp[4*r+c] = State[r][c];
}
}
for (r = 1; r < 4; r++) // shift temp into State
{
for (c = 0; c < 4; c++)
{
State[r][c] = temp[ 4*r+ (c + r) % Nb ];
}
}
} // ShiftRows()
void AES::InvShiftRows()
{
unsigned char temp[4*4];
int r,c;
for (r = 0; r < 4; r++) // copy State into temp[]
{
for (c = 0; c < 4; c++)
{
temp[4*r+c] = State[r][c];
}
}
for (r = 1; r < 4; r++) // shift temp into State
{
for (c = 0; c < 4; c++)
{
State[r][ (c + r) % Nb ] = temp[4*r+c];
}
}
} // InvShiftRows()

void AES::ShiftRows()

{

    unsigned char temp[4*4];

    int r,c;

    for (r = 0; r < 4; r++)  // copy State into temp[]

    {

        for (c = 0; c < 4; c++)

        {

            temp[4*r+c] =  State[r][c];

        }

    }

    for (r = 1; r < 4; r++)  // shift temp into State

    {

        for (c = 0; c < 4; c++)

        {

            State[r][c] = temp[ 4*r+ (c + r) % Nb ];

        }

    }

}  // ShiftRows()

void AES::InvShiftRows()

{

    unsigned char temp[4*4];

    int r,c;

    for (r = 0; r < 4; r++)  // copy State into temp[]

    {

        for (c = 0; c < 4; c++)

        {

            temp[4*r+c] =  State[r][c];

        }

    }

    for (r = 1; r < 4; r++)  // shift temp into State

    {

        for (c = 0; c < 4; c++)

        {

            State[r][ (c + r) % Nb ] = temp[4*r+c];

        }

    }

}  // InvShiftRows()

6 列混淆(Mix Columns) 如图5所示，列变换的中间状态矩阵State如下所示：

AES加解密算法Qt实现

经过上述变换，原来的列被混淆为新列。 AES加解密算法Qt实现

图5 Mix Column

void AES::MixColumns()
{
unsigned char temp[4*4];
int r,c;
for (r = 0; r < 4; r++) // copy State into temp[]
{
for (c = 0; c < 4; c++)
{
temp[4*r+c] = State[r][c];
}
}
for (c = 0; c < 4; c++)
{
State[0][c] = (unsigned char) ( (int)gfmultby02(temp[0+c]) ^ (int)gfmultby03(temp[4*1+c]) ^
(int)gfmultby01(temp[4*2+c]) ^ (int)gfmultby01(temp[4*3+c]) );
State[1][c] = (unsigned char) ( (int)gfmultby01(temp[0+c]) ^ (int)gfmultby02(temp[4*1+c]) ^
(int)gfmultby03(temp[4*2+c]) ^ (int)gfmultby01(temp[4*3+c]) );
State[2][c] = (unsigned char) ( (int)gfmultby01(temp[0+c]) ^ (int)gfmultby01(temp[4*1+c]) ^
(int)gfmultby02(temp[4*2+c]) ^ (int)gfmultby03(temp[4*3+c]) );
State[3][c] = (unsigned char) ( (int)gfmultby03(temp[0+c]) ^ (int)gfmultby01(temp[4*1+c]) ^
(int)gfmultby01(temp[4*2+c]) ^ (int)gfmultby02(temp[4*3+c]) );
}
} // MixColumns
void AES::InvMixColumns()
{
unsigned char temp[4*4];
int r,c;
for (r = 0; r < 4; r++) // copy State into temp[]
{
for (c = 0; c < 4; c++)
{
temp[4*r+c] = State[r][c];
}
}
for (c = 0; c < 4; c++)
{
State[0][c] = (unsigned char) ( (int)gfmultby0e(temp[c]) ^ (int)gfmultby0b(temp[4+c]) ^
(int)gfmultby0d(temp[4*2+c]) ^ (int)gfmultby09(temp[4*3+c]) );
State[1][c] = (unsigned char) ( (int)gfmultby09(temp[c]) ^ (int)gfmultby0e(temp[4+c]) ^
(int)gfmultby0b(temp[4*2+c]) ^ (int)gfmultby0d(temp[4*3+c]) );
State[2][c] = (unsigned char) ( (int)gfmultby0d(temp[c]) ^ (int)gfmultby09(temp[4+c]) ^
(int)gfmultby0e(temp[4*2+c]) ^ (int)gfmultby0b(temp[4*3+c]) );
State[3][c] = (unsigned char) ( (int)gfmultby0b(temp[c]) ^ (int)gfmultby0d(temp[4+c]) ^
(int)gfmultby09(temp[4*2+c]) ^ (int)gfmultby0e(temp[4*3+c]) );
}
} // InvMixColumns
unsigned char AES::gfmultby01(unsigned char b)
{
return b;
}
unsigned char AES::gfmultby02(unsigned char b)
{
if (b < 0x80)
return (unsigned char)(int)(b <<1);
else
return (unsigned char)( (int)(b << 1) ^ (int)(0x1b) );
}
unsigned char AES::gfmultby03(unsigned char b)
{
return (unsigned char) ( (int)gfmultby02(b) ^ (int)b );
}
unsigned char AES::gfmultby09(unsigned char b)
{
return (unsigned char)( (int)gfmultby02(gfmultby02(gfmultby02(b))) ^
(int)b );
}
unsigned char AES::gfmultby0b(unsigned char b)
{
return (unsigned char)( (int)gfmultby02(gfmultby02(gfmultby02(b))) ^
(int)gfmultby02(b) ^
(int)b );
}
unsigned char AES::gfmultby0d(unsigned char b)
{
return (unsigned char)( (int)gfmultby02(gfmultby02(gfmultby02(b))) ^
(int)gfmultby02(gfmultby02(b)) ^
(int)(b) );
}
unsigned char AES::gfmultby0e(unsigned char b)
{
return (unsigned char)( (int)gfmultby02(gfmultby02(gfmultby02(b))) ^
(int)gfmultby02(gfmultby02(b)) ^
(int)gfmultby02(b) );
}

void AES::MixColumns()

{

    unsigned char temp[4*4];

    int r,c;

    for (r = 0; r < 4; r++)  // copy State into temp[]

    {

        for (c = 0; c < 4; c++)

        {

            temp[4*r+c] =  State[r][c];

        }

    }

    for (c = 0; c < 4; c++)

    {

        State[0][c] = (unsigned char) ( (int)gfmultby02(temp[0+c]) ^ (int)gfmultby03(temp[4*1+c]) ^

                                        (int)gfmultby01(temp[4*2+c]) ^ (int)gfmultby01(temp[4*3+c]) );

        State[1][c] = (unsigned char) ( (int)gfmultby01(temp[0+c]) ^ (int)gfmultby02(temp[4*1+c]) ^

                                        (int)gfmultby03(temp[4*2+c]) ^ (int)gfmultby01(temp[4*3+c]) );

        State[2][c] = (unsigned char) ( (int)gfmultby01(temp[0+c]) ^ (int)gfmultby01(temp[4*1+c]) ^

                                        (int)gfmultby02(temp[4*2+c]) ^ (int)gfmultby03(temp[4*3+c]) );

        State[3][c] = (unsigned char) ( (int)gfmultby03(temp[0+c]) ^ (int)gfmultby01(temp[4*1+c]) ^

                                        (int)gfmultby01(temp[4*2+c]) ^ (int)gfmultby02(temp[4*3+c]) );

    }

}  // MixColumns

void AES::InvMixColumns()

{

    unsigned char temp[4*4];

    int r,c;

    for (r = 0; r < 4; r++)  // copy State into temp[]

    {

        for (c = 0; c < 4; c++)

        {

            temp[4*r+c] =  State[r][c];

        }

    }

    for (c = 0; c < 4; c++)

    {

        State[0][c] = (unsigned char) ( (int)gfmultby0e(temp[c]) ^ (int)gfmultby0b(temp[4+c]) ^

                                        (int)gfmultby0d(temp[4*2+c]) ^ (int)gfmultby09(temp[4*3+c]) );

        State[1][c] = (unsigned char) ( (int)gfmultby09(temp[c]) ^ (int)gfmultby0e(temp[4+c]) ^

                                        (int)gfmultby0b(temp[4*2+c]) ^ (int)gfmultby0d(temp[4*3+c]) );

        State[2][c] = (unsigned char) ( (int)gfmultby0d(temp[c]) ^ (int)gfmultby09(temp[4+c]) ^

                                        (int)gfmultby0e(temp[4*2+c]) ^ (int)gfmultby0b(temp[4*3+c]) );

        State[3][c] = (unsigned char) ( (int)gfmultby0b(temp[c]) ^ (int)gfmultby0d(temp[4+c]) ^

                                        (int)gfmultby09(temp[4*2+c]) ^ (int)gfmultby0e(temp[4*3+c]) );

    }

}  // InvMixColumns

unsigned char AES::gfmultby01(unsigned char b)

{

    return b;

}

unsigned char AES::gfmultby02(unsigned char b)

{

    if (b < 0x80)

        return (unsigned char)(int)(b <<1);

    else

        return (unsigned char)( (int)(b << 1) ^ (int)(0x1b) );

}

unsigned char AES::gfmultby03(unsigned char b)

{

    return (unsigned char) ( (int)gfmultby02(b) ^ (int)b );

}

unsigned char AES::gfmultby09(unsigned char b)

{

    return (unsigned char)( (int)gfmultby02(gfmultby02(gfmultby02(b))) ^

                            (int)b );

}

unsigned char AES::gfmultby0b(unsigned char b)

{

    return (unsigned char)( (int)gfmultby02(gfmultby02(gfmultby02(b))) ^

                            (int)gfmultby02(b) ^

                            (int)b );

}

unsigned char AES::gfmultby0d(unsigned char b)

{

    return (unsigned char)( (int)gfmultby02(gfmultby02(gfmultby02(b))) ^

                            (int)gfmultby02(gfmultby02(b)) ^

                            (int)(b) );

}

unsigned char AES::gfmultby0e(unsigned char b)

{

    return (unsigned char)( (int)gfmultby02(gfmultby02(gfmultby02(b))) ^

                            (int)gfmultby02(gfmultby02(b)) ^

                            (int)gfmultby02(b) );

}

7 AES加密加密时，首先进行密钥扩展。密钥扩展的结果是将初始密钥按照一定的移位和置换操作扩展为11组128位的密钥，存储在一个W[44][4]的数组里。将输入的明文，按列顺序组合成4×4的矩阵，直接与第0组密钥W[0,3](即基密钥Key)进行异或，作为轮加密的输入。然后，循环10次进行字节替代(Substitute Bytes)、行位移(Shift Rows)、列混淆(Mix Columns)、轮密钥加运算(Add Round Key)。最后一轮运算不进行列混淆变换。最后，输出128位的密文比特流。

void AES::Cipher(unsigned char* input, unsigned char* output) // encipher 16-bit input
{
// state = input
memset(&State[0][0],0,16);
int i;
for (i = 0; i < (4 * Nb); i++)//
{
State[i % 4][ i / 4] = input[i];
}
AddRoundKey(0);
for (int round = 1; round <= (Nr - 1); round++) // main round loop
{
SubBytes();
ShiftRows();
MixColumns();
AddRoundKey(round);
} // main round loop
SubBytes();
ShiftRows();
AddRoundKey(Nr);
// output = state
for (i = 0; i < (4 * Nb); i++)
{
output[i] = State[i % 4][ i / 4];
}
} // Cipher()

void AES::Cipher(unsigned char* input, unsigned char* output)  // encipher 16-bit input

{

    // state = input

    memset(&State[0][0],0,16);

    int i;

    for (i = 0; i < (4 * Nb); i++)//

    {

        State[i % 4][ i / 4] = input[i];

    }

    AddRoundKey(0);

    for (int round = 1; round <= (Nr - 1); round++)  // main round loop

    {

        SubBytes();

        ShiftRows();

        MixColumns();

        AddRoundKey(round);

    }  // main round loop

    SubBytes();

    ShiftRows();

    AddRoundKey(Nr);

    // output = state

    for (i = 0; i < (4 * Nb); i++)

    {

        output[i] =  State[i % 4][ i / 4];

    }

}  // Cipher()

8 AES解密解密时，进行加密过程逆运算，除轮密钥加和密钥扩展不变外，其余都需要进行相应的逆变换。当基密钥正确，并且采用正确的解密算法，点击解密，对文件进行正确解密。

void AES::InvCipher(unsigned char * input, unsigned char * output) // decipher 16-bit input
{
// state = input
int i;
memset(&State[0][0],0,16);
for (i = 0; i < (4 * Nb); i++)
{
State[i % 4][ i / 4] = input[i];
}
AddRoundKey(Nr);
for (int round = Nr-1; round >= 1; round--) // main round loop
{
InvShiftRows();
InvSubBytes();
AddRoundKey(round);
InvMixColumns();
} // end main round loop for InvCipher
InvShiftRows();
InvSubBytes();
AddRoundKey(0);
// output = state
for (i = 0; i < (4 * Nb); i++)
{
output[i] = State[i % 4][ i / 4];
}
} // InvCipher()

void AES::InvCipher(unsigned char * input, unsigned char * output)  // decipher 16-bit input

{

    // state = input

    int i;

    memset(&State[0][0],0,16);

    for (i = 0; i < (4 * Nb); i++)

    {

        State[i % 4][ i / 4] = input[i];

    }

    AddRoundKey(Nr);

    for (int round = Nr-1; round >= 1; round--)  // main round loop

    {

        InvShiftRows();

        InvSubBytes();

        AddRoundKey(round);

        InvMixColumns();

    }  // end main round loop for InvCipher

    InvShiftRows();

    InvSubBytes();

    AddRoundKey(0);

    // output = state

    for (i = 0; i < (4 * Nb); i++)

    {

        output[i] =  State[i % 4][ i / 4];

    }

}  // InvCipher()

【算法举例】

void print(const char *key, unsigned char* value)
{
int i;
printf("%s:\n", key);
for(i=0; i<16; i++)
{
printf("%s%#x ", value[i]>15 ? "" : "0", value[i]);
}
printf("\n");
}
unsigned char input[] =
{
0x32, 0x43, 0xf6, 0xa8,
0x88, 0x5a, 0x30, 0x8d,
0x31, 0x31, 0x98, 0xa2,
0xe0, 0x37, 0x07, 0x34
};
unsigned char output[16] = { 0 };
unsigned char key[] =
{
0x2b, 0x7e, 0x15, 0x16,
0x28, 0xae, 0xd2, 0xa6,
0xab, 0xf7, 0x15, 0x88,
0x09, 0xcf, 0x4f, 0x3c
};
AES aes(Bits128,key);
//-1-
print("Input", input);
aes.Cipher(input,output);
print("After Cipher", output);
aes.InvCipher(output,input);
print("After InvCipher", input);

void print(const char *key, unsigned char* value)

{

    int i;

    printf("%s:\n", key);

    for(i=0; i<16; i++)

    {

        printf("%s%#x ", value[i]>15 ? "" : "0", value[i]);

    }

    printf("\n");

}

unsigned char input[] =

{

        0x32, 0x43, 0xf6, 0xa8,

        0x88, 0x5a, 0x30, 0x8d,

        0x31, 0x31, 0x98, 0xa2,

        0xe0, 0x37, 0x07, 0x34

};

unsigned char output[16] = { 0 };

unsigned char key[] =

{

        0x2b, 0x7e, 0x15, 0x16,

        0x28, 0xae, 0xd2, 0xa6,

        0xab, 0xf7, 0x15, 0x88,

        0x09, 0xcf, 0x4f, 0x3c

};

AES aes(Bits128,key);

//-1-

print("Input", input);

aes.Cipher(input,output);

print("After Cipher", output);

aes.InvCipher(output,input);

print("After InvCipher", input);

【文件加密】

本文仅分析AES算法本身，不就AES文件加密进行分析。源码中的文件加密功能仅供测试用。实际使用时，文件加密可使用多线程，要考虑加锁、明文字节填充等问题。

【源码下载】

http://download.csdn.net/detail/tandesir/4613524

【参考文献】

1 http://zh.wikipedia.org/wiki/%E9%AB%98%E7%BA%A7%E5%8A%A0%E5%AF%86%E6%A0%87%E5%87%86

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AES加解密算法Qt实现

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