xxtea的加密和解密

2024-11-28 技术教程

xxtea.c

#include "./xxtea.h"#include <memory.h>#include <stdlib.h>static 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; }}static 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; }}static unsigned char *fix_key_length(unsigned char *key, xxtea_long key_len){ unsigned char *tmp = (unsigned char *)malloc(16); memcpy(tmp, key, key_len); memset(tmp + key_len, '\0', 16 - key_len); return tmp;}static xxtea_long *xxtea_to_long_array(unsigned char *data, xxtea_long len, int include_length, xxtea_long *ret_len) { xxtea_long i, n, *result; n = len >> 2; n = (((len & 3) == 0) ? n : n + 1); if (include_length) { result = (xxtea_long *)malloc((n + 1) << 2); result[n] = len; *ret_len = n + 1; } else { result = (xxtea_long *)malloc(n << 2); *ret_len = n; } memset(result, 0, n << 2); for (i = 0; i < len; i++) { result[i >> 2] |= (xxtea_long)data[i] << ((i & 3) << 3); } return result;}static unsigned char *xxtea_to_byte_array(xxtea_long *data, xxtea_long len, int include_length, xxtea_long *ret_len) { xxtea_long i, n, m; unsigned char *result; n = len << 2; if (include_length) { m = data[len - 1]; if ((m < n - 7) || (m > n - 4)) return NULL; n = m; } result = (unsigned char *)malloc(n + 1); for (i = 0; i < n; i++) { result[i] = (unsigned char)((data[i >> 2] >> ((i & 3) << 3)) & 0xff); } result[n] = '\0'; *ret_len = n; return result;}static unsigned char *do_xxtea_encrypt(unsigned char *data, xxtea_long len, unsigned char *key, xxtea_long *ret_len) { unsigned char *result; xxtea_long *v, *k, v_len, k_len; v = xxtea_to_long_array(data, len, 1, &v_len); k = xxtea_to_long_array(key, 16, 0, &k_len); xxtea_long_encrypt(v, v_len, k); result = xxtea_to_byte_array(v, v_len, 0, ret_len); free(v); free(k); return result;}static unsigned char *do_xxtea_decrypt(unsigned char *data, xxtea_long len, unsigned char *key, xxtea_long *ret_len) { unsigned char *result; xxtea_long *v, *k, v_len, k_len; v = xxtea_to_long_array(data, len, 0, &v_len); k = xxtea_to_long_array(key, 16, 0, &k_len); xxtea_long_decrypt(v, v_len, k); result = xxtea_to_byte_array(v, v_len, 1, ret_len); free(v); free(k); return result;}unsigned char *xxtea_encrypt(unsigned char *data, xxtea_long data_len, unsigned char *key, xxtea_long key_len, xxtea_long *ret_length){ unsigned char *result; *ret_length = 0; if (key_len < 16) { unsigned char *key2 = fix_key_length(key, key_len); result = do_xxtea_encrypt(data, data_len, key2, ret_length); free(key2); } else { result = do_xxtea_encrypt(data, data_len, key, ret_length); } return result;}unsigned char *xxtea_decrypt(unsigned char *data, xxtea_long data_len, unsigned char *key, xxtea_long key_len, xxtea_long *ret_length){ unsigned char *result; *ret_length = 0; if (key_len < 16) { unsigned char *key2 = fix_key_length(key, key_len); result = do_xxtea_decrypt(data, data_len, key2, ret_length); free(key2); } else { result = do_xxtea_decrypt(data, data_len, key, ret_length); } return result;}

xxtea.h

#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#include <inttypes.h>#else#include <stdint.h>#endiftypedef uint32_t xxtea_long;#endif#define XXTEA_MX (z >> 5 ^ y << 2) + (y >> 3 ^ z << 4) ^ (sum ^ y) + (k[p & 3 ^ e] ^ z)#define XXTEA_DELTA 0x9E3779B9unsigned char *xxtea_encrypt(unsigned char *data, xxtea_long data_len, unsigned char *key, xxtea_long key_len, xxtea_long *ret_length);unsigned char *xxtea_decrypt(unsigned char *data, xxtea_long data_len, unsigned char *key, xxtea_long key_len, xxtea_long *ret_length);#endif

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include:

extern "C" {#include "xxtea.h"}

用法:

unsigned long tmpSize = 0; unsigned char* tmpBuffer = CCFileUtils::sharedFileUtils()->getFileData(filename.c_str(), "rb", &tmpSize);//读取文件 if (!tmpBuffer){ return 1; } unsigned int codeBufferSize = 0; unsigned char* codeBuffer = xxtea_decrypt(tmpBuffer, tmpSize, (unsigned char*)SCRIPT_KEY, sizeof(SCRIPT_KEY), &codeBufferSize); //解密 delete[] tmpBuffer; if (codeBuffer) { // 解密之后的真实数据}