簡單有效源碼密碼編譯演算法-TEA和XTEA演算法

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最近在項目中用到了XTEA源碼密碼編譯演算法，寫下來總結一下：

TEA（Tiny Encryption Algorithm）是一種小型的對稱式加密解密演算法，支援128位密碼，與BlowFish一樣TEA每次只能加密/解密8位元組資料。TEA特點是速度 快、效率高，實現也非常簡單。由於針對TEA的攻擊不斷出現，所以TEA也發展出幾個版本，分別是XTEA、Block TEA和XXTEA。

TEA演算法實現非常簡單，不到20代碼，分享一個加強版的TEA演算法XTEA演算法實現：

/************************************************************************

Copyright 2006-2007 Ma Bingyao

These sources is free software. Redistributions of source code must
retain the above copyright notice. Redistributions in binary form
must reproduce the above copyright notice. You can redistribute it
freely. You can use it with any free or commercial software.

These sources is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY. Without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

You may contact the author by:
e-mail:  [email protected]

*************************************************************************/

#ifndef XXTEA_H
#define XXTEA_H

#include <stddef.h> /** for size_t & NULL declarations */

#if defined(_MSC_VER)

typedef unsigned __int32 xxtea_long;

#else

#if defined(__FreeBSD__) && __FreeBSD__ < 5
/** FreeBSD 4 doesn’t have stdint.h file */
#include <inttypes.h>
#else
#include <stdint.h>
#endif

typedef uint32_t xxtea_long;

#endif /** end of if defined(_MSC_VER) */

#define XXTEA_MX (z >> 5 ^ y << 2) + (y >> 3 ^ z << 4) ^ (sum ^ y) + (k[p & 3 ^ e] ^ z)
#define XXTEA_DELTA 0x9e3779b9

void xxtea_long_encrypt(xxtea_long *v, xxtea_long len, xxtea_long *k);
void xxtea_long_decrypt(xxtea_long *v, xxtea_long len, xxtea_long *k);

#endif

 

/************************************************************************

Copyright 2006-2007 Ma Bingyao

These sources is free software. Redistributions of source code must
retain the above copyright notice. Redistributions in binary form
must reproduce the above copyright notice. You can redistribute it
freely. You can use it with any free or commercial software.

These sources is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY. Without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

You may contact the author by:
e-mail:  [email protected]

*************************************************************************/
#include “xxtea.h”

void xxtea_long_encrypt(xxtea_long *v, xxtea_long len, xxtea_long *k) {
xxtea_long n = len – 1;
xxtea_long z = v[n], y = v[0], p, q = 6 + 52 / (n + 1), sum = 0, e;
if (n < 1) {
return;
}
while (0 < q–) {
sum += XXTEA_DELTA;
e = sum >> 2 & 3;
for (p = 0; p < n; p++) {
y = v[p + 1];
z = v[p] += XXTEA_MX;
}
y = v[0];
z = v[n] += XXTEA_MX;
}
}

void xxtea_long_decrypt(xxtea_long *v, xxtea_long len, xxtea_long *k) {
xxtea_long n = len – 1;
xxtea_long z = v[n], y = v[0], p, q = 6 + 52 / (n + 1), sum = q * XXTEA_DELTA, e;
if (n < 1) {
return;
}
while (sum != 0) {
e = sum >> 2 & 3;
for (p = n; p > 0; p–) {
z = v[p - 1];
y = v[p] -= XXTEA_MX;
}
z = v[n];
y = v[0] -= XXTEA_MX;
sum -= XXTEA_DELTA;
}
}

簡單有效源碼密碼編譯演算法-TEA和XTEA演算法