网络请求中为了数据的安全性 , 通常会对数据进行加密之后再以JSON形式传输到后台 . 就算请求被拦截 , 也可以有效的保护用户信息的安全性 . 今天就分享一下 常用的一些加密技术 .
MD5 加密
MD5是利用哈希算法来加密的。哈希算法是一种摘要算法，MD5有以下两个最主要的特性 , 常用于用户密码的加密使用。
- 加密的不可逆性，只能够加密，不能够解密。
- 任意长度的明文经过加密后长度都是固定的，长度为16进制32位。
使用MD5 加密之前应该先导入框架 #import "CommonCrypto/CommonDigest.h"
// MD5 转码
-(NSString *) md5: (NSString *) inPutText
{
const char *cStr = [inPutText UTF8String];
unsigned char result[CC_MD5_DIGEST_LENGTH];
CC_MD5(cStr, (CC_LONG)strlen(cStr), result);
return [[NSString stringWithFormat:@"%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X",
result[0], result[1], result[2], result[3],
result[4], result[5], result[6], result[7],
result[8], result[9], result[10], result[11],
result[12], result[13], result[14], result[15]
] lowercaseString];
}
DES加密
DES 加密是一种对称式加密方法 . 其特点是
- 加密与解密使用同一套密钥 , 使用方便 .
- 具有相当高的复杂性, 其安全性仅以加密密钥的保密为基础 .
与MD5 一样也需要导入框架#import "CommonCrypto/CommonDigest.h"
然后还要导入GTMBase64文件
//加密
+(NSString *)decryptWithContent:(NSString *)content
{
//密钥 "abc123"
char * keyChar =(char*)[@"abc123" UTF8String];
if (content == nil) {
content = @"";
}
NSString *jm = [NSString stringWithCString:encryptWithKeyAndType([content UTF8String], kCCEncrypt, keyChar) encoding:NSUTF8StringEncoding];
return jm;
}
//解密
+ (NSData *)encryptWithContent:(NSData *)content
{
NSString *contentStr = [[NSString alloc] initWithData:content encoding:NSUTF8StringEncoding];
if (contentStr == nil || [contentStr isEqualToString:@""]) {
return nil;
}
const char * contentChar =[contentStr UTF8String];
//密钥 "abc123"
char * keyChar =(char*)[@"abc123" UTF8String];
const char *miChar;
miChar = encryptWithKeyAndType(contentChar, kCCDecrypt, keyChar);
if (miChar == nil) {
miChar = "";
}
NSString *zmStr = [NSString stringWithCString:miChar encoding:NSUTF8StringEncoding];
if (zmStr == nil) {
zmStr =@"";
}
return [zmStr dataUsingEncoding:NSUTF8StringEncoding];
}
//核心代码
static const char* encryptWithKeyAndType(const char *text,CCOperation encryptOperation,char *key)
{
NSString *textString=[[NSString alloc]initWithCString:text encoding:NSUTF8StringEncoding];
// NSLog(@"[[item.url description] UTF8String=%@",textString);
const void *dataIn;
size_t dataInLength;
if (encryptOperation == kCCDecrypt)//传递过来的是decrypt 解码
{
//解码 base64
NSData *decryptData = [GTMBase64 decodeData:[textString dataUsingEncoding:NSUTF8StringEncoding]];//转成utf-8并decode
dataInLength = [decryptData length];
dataIn = [decryptData bytes];
}
else //encrypt
{
NSData* encryptData = [textString dataUsingEncoding:NSUTF8StringEncoding];
dataInLength = [encryptData length];
dataIn = (const void *)[encryptData bytes];
}
CCCryptorStatus ccStatus;
uint8_t *dataOut = NULL; //可以理解位type/typedef 的缩写（有效的维护了代码，比如：一个人用int，一个人用long。最好用typedef来定义）
size_t dataOutAvailable = 0; //size_t 是操作符sizeof返回的结果类型
size_t dataOutMoved = 0;
dataOutAvailable = (dataInLength + kCCBlockSizeDES) & ~(kCCBlockSizeDES - 1);
dataOut = malloc( dataOutAvailable * sizeof(uint8_t));
memset((void *)dataOut, 00, dataOutAvailable);//将已开辟内存空间buffer的首 1 个字节的值设为值 0
//NSString *initIv = @"12345678";
const void *vkey = key;
const void *iv = (const void *) key; //[initIv UTF8String];
//CCCrypt函数 加密/解密
ccStatus = CCCrypt(encryptOperation,// 加密/解密
kCCAlgorithmDES,// 加密根据哪个标准（des，3des，aes。。。。）
kCCOptionPKCS7Padding,// 选项分组密码算法(des:对每块分组加一次密 3DES：对每块分组加三个不同的密)
vkey, //密钥 加密和解密的密钥必须一致
kCCKeySizeDES,// DES 密钥的大小（kCCKeySizeDES=8）
iv, // 可选的初始矢量
dataIn, // 数据的存储单元
dataInLength,// 数据的大小
(void *)dataOut,// 用于返回数据
dataOutAvailable,
&dataOutMoved);
NSString *result = nil;
if (encryptOperation == kCCDecrypt)//encryptOperation==1 解码
{
//得到解密出来的data数据，改变为utf-8的字符串
result = [[NSString alloc] initWithData:[NSData dataWithBytes:(const void *)dataOut length:(NSUInteger)dataOutMoved] encoding:NSUTF8StringEncoding];
}
else //encryptOperation==0 （加密过程中，把加好密的数据转成base64的）
{
//编码 base64
NSData *data = [NSData dataWithBytes:(const void *)dataOut length:(NSUInteger)dataOutMoved];
result = [GTMBase64 stringByEncodingData:data];
}
return [result UTF8String];
}
AES加密
AES加密是一种更高级的对称加密算法 . 其特点是
- 密钥为128位(也有192-256的变体) , 相比DES(56位)更安全.
- 隐藏了明文模式 , 分组密码转化为流模式
先导入框架 #import <CommonCrypto/CommonCryptor.h>
代码下载地址
//加密
- (NSData *)AES256EncryptWithKey:(NSString *)key {
// 'key' should be 32 bytes for AES256, will be null-padded otherwise
char keyPtr[kCCKeySizeAES256+1]; // room for terminator (unused)
bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding)
// fetch key data
[key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
NSUInteger dataLength = [self length];
//See the doc: For block ciphers, the output size will always be less than or
//equal to the input size plus the size of one block.
//That's why we need to add the size of one block here
size_t bufferSize = dataLength + kCCBlockSizeAES128;
void *buffer = malloc(bufferSize);
size_t numBytesEncrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt,
kCCAlgorithmAES128,
kCCOptionPKCS7Padding,
keyPtr, kCCKeySizeAES256,
NULL /* initialization vector (optional) */,
[self bytes], dataLength, /* input */
buffer, bufferSize, /* output */
&numBytesEncrypted);
if (cryptStatus == kCCSuccess) {
//the returned NSData takes ownership of the buffer and will free it on deallocation
return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
}
free(buffer); //free the buffer;
return nil;
}
//解密
- (NSData *)AES256DecryptWithKey:(NSString *)key {
// 'key' should be 32 bytes for AES256, will be null-padded otherwise
char keyPtr[kCCKeySizeAES256+1]; // room for terminator (unused)
bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding)
// fetch key data
[key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
NSUInteger dataLength = [self length];
//See the doc: For block ciphers, the output size will always be less than or
//equal to the input size plus the size of one block.
//That's why we need to add the size of one block here
size_t bufferSize = dataLength + kCCBlockSizeAES128;
void *buffer = malloc(bufferSize);
size_t numBytesDecrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding,
keyPtr, kCCKeySizeAES256,
NULL /* initialization vector (optional) */,
[self bytes], dataLength, /* input */
buffer, bufferSize, /* output */
&numBytesDecrypted);
if (cryptStatus == kCCSuccess) {
//the returned NSData takes ownership of the buffer and will free it on deallocation
return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
}
free(buffer); //free the buffer;
return nil;
}
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