使用 DataContractSerializer 和 DataProtectionProvider 序列化和加密对象

本文关键字：加密 对象 序列化 DataProtectionProvider DataContractSerializer 使用 | 更新日期: 2023-09-27 18:31:41

我正在尝试将对象序列化为内存流，然后加密此流，然后将其写入文件。无法弄清楚出了什么问题，"解密"后内存流为空。

    public static async Task SerializeToFileEncrypt<T>(T o, StorageFile file)
    {
            DataContractSerializer dsc = new DataContractSerializer(typeof(T));                
            MemoryStream memoryStream = new MemoryStream();
            dsc.WriteObject(memoryStream, o);
            DataProtectionProvider provider = new DataProtectionProvider("Local=User");
            var raStream = await file.OpenAsync(FileAccessMode.ReadWrite);
            using(var filestream = raStream.GetOutputStreamAt(0))
            {
                await provider.ProtectStreamAsync(memoryStream.AsInputStream(), filestream);
                await filestream.FlushAsync();                        
            }
    }
    public static async Task<T> DeserializeFromFileDecrypt<T>(StorageFile file)
    {
        DataContractSerializer dsc = new DataContractSerializer(typeof(T));
        MemoryStream memoryStream = new MemoryStream();
        DataProtectionProvider provider = new DataProtectionProvider();
        await provider.UnprotectStreamAsync((await file.OpenStreamForReadAsync()).AsInputStream(), memoryStream.AsOutputStream());
        return (T) dsc.ReadObject(memoryStream);
    }

使用 DataContractSerializer 和 DataProtectionProvider 序列化和加密对象

完成

写入后，您需要移动到MemoryStream的开头。否则，没有什么可读的，因为你已经定位在最后。

这应该有效：

public static async Task SerializeToFileEncrypt<T>(T o, StorageFile file)
{
        DataContractSerializer dsc = new DataContractSerializer(typeof(T));                
        MemoryStream memoryStream = new MemoryStream();
        dsc.WriteObject(memoryStream, o);
        memoryStream.Seek(0, SeekOrigin.Begin); // move to the beginning of the stream
        DataProtectionProvider provider = new DataProtectionProvider("Local=User");
        var raStream = await file.OpenAsync(FileAccessMode.ReadWrite);
        using(var filestream = raStream.GetOutputStreamAt(0))
        {
            await provider.ProtectStreamAsync(memoryStream.AsInputStream(), filestream);
            await filestream.FlushAsync();                        
        }
}
public static async Task<T> DeserializeFromFileDecrypt<T>(StorageFile file)
{
    DataContractSerializer dsc = new DataContractSerializer(typeof(T));
    MemoryStream memoryStream = new MemoryStream();
    DataProtectionProvider provider = new DataProtectionProvider();
    await provider.UnprotectStreamAsync((await file.OpenStreamForReadAsync()).AsInputStream(), memoryStream.AsOutputStream());
    memoryStream.Seek(0, SeekOrigin.Begin); // move to the beginning of the stream
    return (T) dsc.ReadObject(memoryStream);
}

除了上次发布的答案之外，您需要将 raStream 包装在 using 语句中，因为它是一个 IDisposable 对象。 否则，如果某些代码稍后尝试再次打开该文件，它将失败并拒绝访问，因为文件仍由随机访问流打开。

public static async Task SerializeToFileEncrypt<T>(T o, StorageFile file)
        {
            DataContractSerializer dsc = new DataContractSerializer(typeof(T));
            MemoryStream memoryStream = new MemoryStream();
            dsc.WriteObject(memoryStream, o);
            memoryStream.Seek(0, SeekOrigin.Begin); // move to the beginning of the stream
            DataProtectionProvider provider = new DataProtectionProvider("Local=User");
            using (var raStream = await file.OpenAsync(FileAccessMode.ReadWrite))
            {
                using (var filestream = raStream.GetOutputStreamAt(0))
                {
                    await provider.ProtectStreamAsync(memoryStream.AsInputStream(), filestream);
                    await filestream.FlushAsync();
                }
            }
        }
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