【数据加密】使用XXTEA对NSData进行加密
最近做的项目中数据传输要加密，开始使用的是AES加密算法，这个是本来就有高手封装好了的，在ios中对NSData进行加密，拿来直接用就ok了。但是考虑到传输数据大，频率高，服务器每秒可能要跟N多的用户交互，于是另寻它径。
后来了解到XXTEA效率挺高的，测试了一下加密解密可以保证在1毫秒之内完成。ok，就是它了。XXTEA加密算法是对TEA加密算法的升级，仍然是用128位（16字节）的密钥对64位（8字节）信息进行加密，也就是说加密的数据必须是8字节的整数倍，不够的话自动补齐。
不过，XXTEA是C语言实现的，当然没法传递NSData进行加密。网上找了N久，但是好像没有人给出现成的封装方法对NSData加密，只能自己封装了。
直接上代码：
XXTEA的C语言实现：（最原始的代码）
#define MX (z>>5^y<<2) + (y>>3^z<<4)^(sum^y) + (k[p&3^e]^z);
long btea(long* v, long n, long* k) {
unsigned long z=v[n-1], y=v[0], sum=0, e, DELTA=0x9e3779b9;
long p, q ;
if (n > 1) { /* Coding Part */
q = 6 + 52/n;
while (q-- > 0) {
sum += DELTA;
e = (sum >> 2) & 3;
for (p=0; p<n-1; p++) y = v[p+1], z = v[p] += MX;
y = v[0];
z = v[n-1] += MX;
}
return 0 ;
} else if (n < -1) { /* Decoding Part */
n = -n;
q = 6 + 52/n;
sum = q*DELTA ;
while (sum != 0) {
e = (sum >> 2) & 3;
for (p=n-1; p>0; p--) z = v[p-1], y = v[p] -= MX;
z = v[n-1];
y = v[0] -= MX;
sum -= DELTA;
}
return 0;
}
return 1;
}
封装后的程序
**********************************XXTEA.h***********************************
/*
* 此类是对XXTEA官方算法进行的封装，XXTEA信息详见http://en.wikipedia.org/wiki/XXTEA
*/
#ifndef XXTEA_h
#define XXTEA_h
#include "stdlib.h"
#include "stdio.h"
#include <string.h>
#ifndef XXTEA_TYPE
#define XXTEA_TYPE int // 一种32位长的数据类型，因int在32bit和64bit系统中都是32位的，故直接用int
#endif
class XXTEA {
public:
XXTEA();
~XXTEA();
public:
/**
* @brief 获得输出缓冲区的长度
*
* @param nLength 输入缓冲区长度
* @param isEncode TRUE 即为加密，FALSE即为解密
*
* @return 返回所需长度
*/
static size_t XXTEAGetBufferLength(size_t nLength, bool isEncode);
/**
* @brief 对数据流进行加密
*
* @param lpDstBuffer 目标缓冲区
* @param lpSrcBuffer 源缓冲区
* @param nLength 源缓冲区长度
* @param lpKey 密钥
*
* @return 加密是否成功
*/
static bool XXTEAEncode(char* lpDstBuffer, const char* lpSrcBuffer, size_t nLength, const XXTEA_TYPE* lpKey);
/**
* @brief 对数据流进行解密
*
* @param lpDstBuffer 目标缓冲区
* @param lpSrcBuffer 源缓冲区
* @param nLength 源缓冲区长度
* @param lpKey 密钥
*
* @return 解密是否成功
*/
static bool XXTEADecode(char* lpDstBuffer, const char* lpSrcBuffer, size_t nLength, const XXTEA_TYPE* lpKey);
private:
/**
* @brief XXTEA官方算法，此类即是对其进行封装，详见http://en.wikipedia.org/wiki/XXTEA
*
* @param v 加解密数据流
* @param n 加解密长度，n > 1为加密，n < -1为解密
* @param k 密钥 注意：形式参数k需和MX中的k对应
*
* @return 返回0表示加解密成功，返回1表示失败
*/
static long btea(XXTEA_TYPE* v, long n, const XXTEA_TYPE* k);
/**
* @brief 正常字符串以16进制保存
*
* @param surBuffer 源缓冲区
* @param length 源缓冲区长度
* @param dstBuffer 目标缓冲区
*/
static void StringToHex(const char* surBuffer, int length, char* dstBuffer);
/**
* @brief 16进制字符串解析成正常字符串
*
* @param surBuffer 源缓冲区
* @param dstBuffer 目标缓冲区
*
* @return 目标缓冲区的长度
*/
static int HexToString(const char* surBuffer, char* dstBuffer);
};
#endif
**********************************XXTEA.cpp*********************************
#include "XXTEA.h"
#define MX (z>>5^y<<2) + (y>>3^z<<4)^(sum^y) + (k[p&3^e]^z);
#define XXTEA_ALIGNMENT_BYTES 4
XXTEA::XXTEA(){
}
XXTEA::~XXTEA(){
}
size_t XXTEA::XXTEAGetBufferLength(size_t nLength, bool isEncode){
if (isEncode) {
size_t nSize = nLength / XXTEA_ALIGNMENT_BYTES + (nLength % XXTEA_ALIGNMENT_BYTES ? 1 : 0);
return (nSize * XXTEA_ALIGNMENT_BYTES * 2 + 1);
}
else {
return (nLength / 2 + 1);
}
}
bool XXTEA::XXTEAEncode(char* lpDstBuffer, const char* lpSrcBuffer, size_t nLength, const XXTEA_TYPE* lpKey){
long ret = 1;
if (nLength > XXTEA_ALIGNMENT_BYTES && lpDstBuffer && lpSrcBuffer) {
size_t nSize = nLength / XXTEA_ALIGNMENT_BYTES + (nLength % XXTEA_ALIGNMENT_BYTES ? 1 : 0);
char* data = (char*)malloc(nSize * XXTEA_ALIGNMENT_BYTES * 2);
memset(data, 0, nSize * XXTEA_ALIGNMENT_BYTES * 2);
memcpy(data, lpSrcBuffer, nLength);
ret = btea((XXTEA_TYPE*)data, nSize, lpKey);
memset(lpDstBuffer, 0, XXTEAGetBufferLength(nLength, true));
StringToHex(data, (int)nSize * XXTEA_ALIGNMENT_BYTES, lpDstBuffer);
free(data);
}
return (ret == 0);
}
bool XXTEA::XXTEADecode(char* lpDstBuffer, const char* lpSrcBuffer, size_t nLength, const XXTEA_TYPE* lpKey){
long ret = 1;
if (nLength > XXTEA_ALIGNMENT_BYTES * 2 && lpDstBuffer && lpSrcBuffer) {
size_t nSize = XXTEAGetBufferLength(nLength, false);
memset(lpDstBuffer, 0, nSize);
HexToString(lpSrcBuffer, lpDstBuffer);
ret = btea((XXTEA_TYPE*)lpDstBuffer, -((nSize - 1)/ XXTEA_ALIGNMENT_BYTES), lpKey);
}
return (ret == 0);
}
long XXTEA::btea(XXTEA_TYPE* v, long n, const XXTEA_TYPE* k) {
unsigned XXTEA_TYPE z, y;
unsigned long sum = 0, e, DELTA = 0x9e3779b9;
long p, q;
if (n > 1) { /* Coding Part */
z = v[n-1];
q = 6 + 52 / n;
while (q-- > 0) {
sum += DELTA;
e = (sum >> 2) & 3;
for (p = 0; p < n-1; ++p) y = v[p+1], z = v[p] += MX;
y = v[0];
z = v[n-1] += MX;
}
return 0;
} else if (n < -1) { /* Decoding Part */
y = v[0];
n = -n;
q = 6 + 52 / n;
sum = q * DELTA ;
while (sum != 0) {
e = (sum >> 2) & 3;
for (p = n-1; p > 0; --p) z = v[p-1], y = v[p] -= MX;
z = v[n-1];
y = v[0] -= MX;
sum -= DELTA;
}
return 0;
}
return 1;
}
void XXTEA::StringToHex(const char* surBuffer, int length, char* dstBuffer){
for (int i = 0; i < length; i++)
{
sprintf(&dstBuffer[2*i], "%02X", (unsigned char)surBuffer[i]);
}
dstBuffer[2 * length] = '\0';
}
int XXTEA::HexToString(const char* surBuffer, char* dstBuffer){
size_t length = strlen((char*)surBuffer) ;
for(int i = 0; i < length/2; i++)
{
int temp;
sscanf(&surBuffer[2 * i], "%02X", &temp);
dstBuffer[i] = (char)temp;
}
dstBuffer[length/2] = '\0';
return (int)strlen((char*)dstBuffer);
}
********************************XXTEAHELP.h********************************
#import <Foundation/Foundation.h>
@interface XXTEAHELP : NSObject{
}
+(NSData*) encodeWithData:(NSData *)data;
+(NSData*) decodeWithData:(NSData *)data;
@end
********************************XXTEAHELP.mm*******************************
#import "XXTEAHELP.h"
#include "XXTEA.h"
@implementation XXTEAHELP
+(NSData*) encodeWithData:(NSData *)data
{
char *ch = (char *)[data bytes];
size_t length = XXTEA::XXTEAGetBufferLength(strlen(ch) + 1, true);
char* encodeBuffer = new char[length];
XXTEA_TYPE key[4] = {0x12345678, 0x734a67fc, 0x3367a642, 0x78432562};
XXTEA::XXTEAEncode(encodeBuffer, ch, strlen(ch) +1, key);
void *buffer = (void *)encodeBuffer;
data = [NSData dataWithBytes:buffer length:3*(strlen(ch)+1)];
return data;
}
+(NSData*) decodeWithData:(NSData *)data
{
XXTEA_TYPE key[4] = {0x12345678, 0x734a67fc, 0x3367a642, 0x78432562};
const char *en = (const char *)[data bytes];
size_t length = XXTEA::XXTEAGetBufferLength((strlen(en) + 1)/2, true);
char *de = new char[XXTEA::XXTEAGetBufferLength(length, false)];
XXTEA::XXTEADecode(de, en, length, key);
void *buf = (void *)de;
data = [NSData dataWithBytes:buf length:strlen(de)+1];
return data;
}
********************************使用方法*******************************
NSString *str = @"Hello World!hogablgsjlwobg1025";
NSMutableData *data = [[NSMutableData alloc] init];
[data appendData:[str dataUsingEncoding:NSUTF8StringEncoding]];
NSLog(@"加密前：～～～～～～～～～～～～～ %@",data);
data = (NSMutableData *)[XXTEAHELP encodeWithData:data];
NSLog(@"加密后：～～～～～～～～～～～～～ %@",data);
data = (NSMutableData *)[XXTEAHELP decodeWithData:data];
NSLog(@"解密后：～～～～～～～～～～～～～ %@",data);
NSString *s = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];