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我尝试使用 CCCrypt 方法，但它与 XCode4 和 XCode5 的结果不同

 - (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;
}

当我用这条线调用这个方法时......不同的结果

NSString *password = @"E7VRcIXn8yb2Ab+t/in9UzRof6vOpOYebgKbpt1GOcfDF8rpc5nZXngx1G8QfbDqsVrwZw26609GVwruUBrOirCI/WUT8U87fbD6lSy/zPwFIYC113LgXIEylYgzIWO4";
  NSString *pwd = [password AES256DecryptWithKey: @"abcd"];
  if (pwd) {
      NSString *checkKey = @"0sSBf7Ncyov+uzvDikOBiA==";
      NSString *uncryptChk = [checkKey AES256DecryptWithKey: pwd];

在 XCode4 中，结果是"abcd"，而在 XCode5 中，结果是""。

4

1 回答 1

2

我自己遇到了这个问题。似乎他们修复了从 iOS6 到 iOS7 的关于 [NSString keyCString:maxLength:encoding] 的错误 iOS6 上的旧方法会切断部分缓冲区以填充 keyPtr。

一个简单的解决方法是将 keyPTr 大小增加到

char keyPtr = kCCKeySizeAES256 * 2 + 1;

但是请记住，当您将应用程序从 6 升级到 7 时，它应该可以工作。keyCString 截断长度以匹配 keyPtr 的大小。并将第一个字符替换为 0。因此要确保它在两个平台上都有效。添加上面的代码，并设置keyPtr[0] = 0;

于 2013-09-12T12:53:48.400 回答