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要點(diǎn)
- 格式保持加密
- AES加密算法
格式保持加密
格式保持加密是指輸入的明文和輸出的密文是以保持相同的格式冀膝，就是說密文的長度不變悉抵，而格式也與明文相同术羔。如果不保持格式醋粟，就意味著長度會(huì)變化且密文不具有明文所有的格式丛晌，數(shù)據(jù)庫需要為此修改蛉谜，很多方面都會(huì)受到影響部脚，所以格式保持加密在生產(chǎn)生活中十分重要远搪。
這里完成格式保持加密的思路是建立明密文置換表，先對(duì)自然數(shù)進(jìn)行AES加密击碗，加密后的權(quán)值可以進(jìn)行排序筑悴，排序就使得我們加密的域內(nèi)所有字符可以對(duì)應(yīng)其他字符，如：
weight(0) = 0x56c644080098fc5570f2b329323dbf62
weight(1) = 0x08ee98c0d05e3dad3eb3d6236f23e7b7
weight(2) = 0x47d2e1bf72264fa01fb274465e56ba20
weight(3) = 0x077de40941c93774857961a8a772650d
Sorting [0,1,2,3] by weight gives [3,1,2,0], so the cipher is
F(0) = 3
F(1) = 1
F(2) = 2
F(3) = 0.
經(jīng)過加密后：0->3,1->1,2->2,3->0
那么假設(shè)我們的字符集是{a,b,c,d},經(jīng)過上述過程就可以得到
a->d,b->b,c->c,d->a
每個(gè)字符都與其他字符建立了對(duì)應(yīng)關(guān)系稍途，解密則是相反變換阁吝。
這就實(shí)現(xiàn)了格式保持加密。
AES加密算法
高級(jí)加密標(biāo)準(zhǔn)械拍。（這里的AES是簡化處理的突勇，沒有使用隨機(jī)數(shù)装盯，也沒有使用密鑰拓展，而是每一輪都使用同一個(gè)密鑰進(jìn)行加密）過程如下：
int key[128];
int P[128];
const int FSb[256] =
{
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 addRoundKey(int *P,int *key){
// 輪密鑰加
for(int i = 0 ; i < 128 ; i++)P[i] = P[i] ^ key[i];
}
void replace(int *P){
// 字節(jié)替代
for(int i = 0 , j = 0 , k = 0 ,n = 0 , m = 0; i < 121 ; ){
j = (P[i + 3] + 2 * (P[i + 2] + 2 * (P[i + 1] + 2 * P[i])));
k = (P[i + 7] + 2 * (P[i + 6] + 2 * (P[i + 5] + 2 * P[i + 4])));
n = FSb[j * 16 + k];
// printf("%d\n",n);
for(m = i + 7 ; m >= i ; m--){
P[m] = n % 2;
n /= 2;
}
i += 8;
}
}
void shiftRows(int *P){
// 行移位
for(int i = 0 , j = 0 , k = 0 ,temp = 0 ; i < 121 ;){
for(k = 0; k < j ; k++){
temp = P[i + 7];
P[i + 7] = P[i + 6];P[i + 6] = P[i + 5];
P[i + 5] = P[i + 4];P[i + 4] = P[i + 3];
P[i + 3] = P[i + 2];P[i + 2] = P[i + 1];
P[i + 1] = P[i + 0];P[i + 0] = temp;
}
i += 8;
}
}
void mixColumns(int *P){
// 列混淆
int a=2,b=3,c=1,d=1,temp=0;
for(int i = 0 , j = 0 , k = 0 ,n = 0 ; i < 128 ; ){
for(j = 31 + i ; j >= i ; ){
n = (P[j] + 2 * (P[j - 1] + 2 * (P[j - 2] + 2 * (P[j - 3] + 2 * (P[j - 4] + 2 * (P[j - 5] + 2 * (P[j - 6] + 2 * P[j - 7])))))));
n *= d;
temp = d;d = c;c = b;b = a;a = temp;
temp = d;d = c;c = b;b = a;a = temp;
for(k = j ; k >= j - 7 ; k--){
P[k] = n % 2;
n /= 2;
}
j -= 8;
}
i += 32;
}
}
格式保持加密的過程：
int numre[10] = {0,1,2,3,4,5,6,7,8,9};
char charre[26] = {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};
char bcharre[26] = {'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'};
void revertAndSort(){
for(int i = 0 , j = 0 , k = 0
, n = 0 ,max = 0; i < 26 ; i++){
max = weight[i];
for(j = i+1 ; j < 26 ; j++){
if(weight[j] > max){
max = weight[j];
int temp = weight[j];weight[j] = weight[i];weight[i] = temp;
char tempch = charre[j];charre[j] = charre[i];charre[i] = tempch;
tempch = bcharre[j];bcharre[j] = bcharre[i];bcharre[i] = tempch;
if(j < 10){
temp = numre[j];numre[j]= numre[i];numre[i] = temp;
}
}
}
}
}
char encryption(char ch){
if(ch >= 'a' && ch <= 'z'){
ch = charre[ch - 97];
}else if(ch >= 'A' && ch <= 'Z'){
ch = bcharre[ch - 65];
}else if(ch >= '0' && ch <= '9'){
ch = numre[ch - 48] + 48;
}
return ch;
}
char decryption(char ch){
int i = 0;
if(ch >= 'a' && ch <= 'z'){
for(i = 0 ; i < 26 ; i++){
if(charre[i] == ch)break;
}
ch = i+97;
}else if(ch >= 'A' && ch <= 'Z'){
for(i = 0 ; i < 26 ; i++){
if(bcharre[i] == ch)break;
}
ch = i+65;
}else if(ch >= '0' && ch <= '9'){
for(i = 0 ; i < 11 ; i++){
if(numre[i] == ch - 48)break;
}
ch = i+48;
}
return ch;
}
結(jié)果：
