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：

 <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+1];
    memset(keyPtr, 0, sizeof(keyPtr));
    [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];

    char ivPtr[kCCBlockSizeAES128+1];
    memset(ivPtr, 0, 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 = 0;

    if(diff > 0)
    {
        newSize = dataLength + diff;
        NSLog(@"diff is %d",diff);
    }

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

    size_t bufferSize = newSize + kCCBlockSizeAES128;
    void *buffer = malloc(bufferSize);
    memset(buffer, 0, bufferSize);

    size_t numBytesCrypted = 0;

    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==0 ){
        return nil;
    }
    const char *tmpStr=[decoded UTF8String];
    int i=0;

    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 + 1];
    memset(keyPtr, 0, sizeof(keyPtr));
    [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];

    char ivPtr[kCCBlockSizeAES128 + 1];
    memset(ivPtr, 0, 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 = 0;
    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 !=16 ){
        return NO;
    }
    return YES;
}

-(NSString *)processDecodedString:(NSString *)decoded
{
    if( decoded==nil || decoded.length==0 ){
        return nil;
    }
    const char *tmpStr=[decoded UTF8String];
    int i=0;

    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);
?>