IOS 与 PHP 通信加密，使用AES 128 CBC no padding

这个网上的资料真实浩如烟海，但是真正有价值的屈指可数

自己尝试了一天多，终于还是搞定了。

再次要感谢网上的前辈么。

比如下面这个关于php和java端的实现：

http://my.oschina.net/Jacker/blog/86383

关于php和java端的实现。

再比如下面这个关于ios端的实现：

http://www.cnblogs.com/wanyakun/p/3403352.html

为何要采用 no padding 这种形式：

AES加密如果原输入数据不够16字节的整数位，就要补齐，如果采用

pkcs7或者pkcs5这种加密方式，末端添加的数据可能是0x1,0x2,0x3，不固定，

在解码后需要把末端多余的字符去掉，就显得比较棘手。

如果不管补齐多少位，末端都是'\0',去掉的话比较容易操作。

好了，再次确认一下，这里使用的是  AES128 CBC no padding加密解密方式。

先上ios端的代码：

 &nbsp;<pre class="objc" name="code">//
 //  AES128.m
 //  login
 //
 //  Created by wangdan on 15-3-3.
 //  Copyright (c) 2015年 wangdan. All rights reserved.
 //

 #import "AES128.h"

 #import <CommonCrypto/CommonCryptor.h>
 #import "GTMBase64.h"

 @implementation AES128

 +(NSString *)AES128Encrypt:(NSString *)plainText withKey:(NSString *)key
 {

     if( ![self validKey:key] ){
         return nil;
     }

     char keyPtr[kCCKeySizeAES128+];
     memset(keyPtr, , sizeof(keyPtr));
     [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];

     char ivPtr[kCCBlockSizeAES128+];
     memset(ivPtr, , sizeof(ivPtr));
     [key getCString:ivPtr maxLength:sizeof(ivPtr) encoding:NSUTF8StringEncoding];

     NSData* data = [plainText dataUsingEncoding:NSUTF8StringEncoding];
     NSUInteger dataLength = [data length];

     int diff = kCCKeySizeAES128 - (dataLength % kCCKeySizeAES128);
     unsigned long newSize = ;

     if(diff > )
     {
         newSize = dataLength + diff;
         NSLog(@"diff is %d",diff);
     }

     char dataPtr[newSize];
     memcpy(dataPtr, [data bytes], [data length]);
     for(int i = ; i < diff; i++)
     {
         dataPtr[i + dataLength] =0x0000;
     }

     size_t bufferSize = newSize + kCCBlockSizeAES128;
     void *buffer = malloc(bufferSize);
     memset(buffer, , bufferSize);

     size_t numBytesCrypted = ;

     CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt,
                                           kCCAlgorithmAES128,
                                           0x0000,
                                           [key UTF8String],
                                           kCCKeySizeAES128,
                                           [key UTF8String],
                                           dataPtr,
                                           sizeof(dataPtr),
                                           buffer,
                                           bufferSize,
                                           &numBytesCrypted);

     if (cryptStatus == kCCSuccess) {
         NSData *resultData = [NSData dataWithBytesNoCopy:buffer length:numBytesCrypted];
         return [GTMBase64 stringByEncodingData:resultData];
     }
     free(buffer);
     return nil;
 }

 +(NSString *)processDecodedString:(NSString *)decoded
 {
     if( decoded==nil || decoded.length== ){
         return nil;
     }
     const char *tmpStr=[decoded UTF8String];
     int i=;

     while( tmpStr[i]!='\0' )
     {
         i++;
     }
     NSString *final=[[NSString alloc]initWithBytes:tmpStr length:i encoding:NSUTF8StringEncoding];
     return final;

 }

 +(NSString *)AES128Decrypt:(NSString *)encryptText withKey:(NSString *)key
 {

     if( ![self validKey:key] ){
         return nil;
     }

     char keyPtr[kCCKeySizeAES128 + ];
     memset(keyPtr, , sizeof(keyPtr));
     [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];

     char ivPtr[kCCBlockSizeAES128 + ];
     memset(ivPtr, , sizeof(ivPtr));
     [key getCString:ivPtr maxLength:sizeof(ivPtr) encoding:NSUTF8StringEncoding];

     NSData *data = [GTMBase64 decodeData:[encryptText dataUsingEncoding:NSUTF8StringEncoding]];
     NSUInteger dataLength = [data length];
     size_t bufferSize = dataLength + kCCBlockSizeAES128;
     void *buffer = malloc(bufferSize);

     size_t numBytesCrypted = ;
     CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt,
                                           kCCAlgorithmAES128,
                                           0x0000,
                                           [key UTF8String],
                                           kCCBlockSizeAES128,
                                           [key UTF8String],
                                           [data bytes],
                                           dataLength,
                                           buffer,
                                           bufferSize,
                                           &numBytesCrypted);
     if (cryptStatus == kCCSuccess) {
         NSData *resultData = [NSData dataWithBytesNoCopy:buffer length:numBytesCrypted];

         NSString *decoded=[[NSString alloc] initWithData:resultData encoding:NSUTF8StringEncoding];
         return [self processDecodedString:decoded];
     }

     free(buffer);
     return nil;

 }

 +(BOOL)validKey:(NSString*)key
 {
     if( key==nil || key.length != ){
         return NO;
     }
     return YES;
 }

 -(NSString *)processDecodedString:(NSString *)decoded
 {
     if( decoded==nil || decoded.length== ){
         return nil;
     }
     const char *tmpStr=[decoded UTF8String];
     int i=;

     while( tmpStr[i]!='\0' )
     {
         i++;
     }
     NSString *final=[[NSString alloc]initWithBytes:tmpStr length:i encoding:NSUTF8StringEncoding];
     return final;

 }

 @end

上述代码需要说明的是，进行AES编码时，输入编码必须是16字节的整数倍，不然调用ios 的系统api会报错 -4003

补齐的字节数全部填充为0

另外  processDecodedString这个函数为了把解码后的字符串，末尾去掉'\0'

下面是PHP端的代码，这个代码是大神些写的啊，经过实际实验是能使用的：

 <?php
 $privateKey = "1234567812345678";
 $iv     = "1234567812345678";
 $data   = "Test String";

 //加密
 $encrypted = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $privateKey, $data, MCRYPT_MODE_CBC, $iv);
 echo(base64_encode($encrypted));
 echo '<br/>';

 //解密
 $encryptedData = base64_decode("2fbwW9+8vPId2/foafZq6Q==");
 $decrypted = mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $privateKey, $encryptedData, MCRYPT_MODE_CBC, $iv);
 echo($decrypted);
 ?>