1.起因是配合服务端进行加密工作，一开始使用AES256，并对比一个AES在线加密的网站
2.出现的状况是AES128可以匹配上网站的结果，AES256无论怎么调整都无法匹配
3.代码如下

   -(NSData *)aes_encryptData:(NSData *)inputData  withKey:(NSString *)key
        {
            NSLog(@"inputData AES %@",inputData);
            char keyPtr[kCCKeySizeAES256+1];
            bzero(keyPtr, sizeof(keyPtr));
            [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
            NSUInteger dataLength = [inputData length];
            size_t bufferSize = dataLength + kCCBlockSizeAES128;
            void *buffer = malloc(bufferSize);
            size_t numBytesEncrypted = 0;
            CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmAES128,
                                                  kCCOptionPKCS7Padding,
                                                  keyPtr, kCCKeySizeAES128,
                                                  NULL,
                                                  [inputData bytes], dataLength,
                                                  buffer, bufferSize,
                                                  &numBytesEncrypted);
            if (cryptStatus == kCCSuccess) {
                return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
            }
            free(buffer);
            return nil;
        }

4.我想知道的是，AES256是否通用，如果通用如何能够得出和网站结果一样的加密串？