c# - 如何从 HttpPostedFileBase file.InputStream 获取 SHA1 和 MD5 校验和

Question

我想在MVC中获取上传文件的校验和。

目前我正在做这个

public ActionResult Index(HttpPostedFileBase file, string path)
{


    if (file != null)
    {

        string checksumMd5    = HashGenerator.GetChecksum(file.InputStream, HashGenerator.MD5);;
        string checksumSha1   = HashGenerator.GetChecksum(file.InputStream, HashGenerator.SHA1);

   //other logic follows....

    }

但是当我在控制台应用程序中执行以下操作并从文件路径读取文件时，

string path = @"C:\Users\anandv4\Desktop\Manifest-5977-681-673.txt";

var md5hash = HashGenerator.GetChecksum(path, HashGenerator.MD5);
var sha1 = HashGenerator.GetChecksum(path, HashGenerator.SHA1);

两者的值不同。

生成哈希的代码:

public static string GetChecksum(string fileName, HashAlgorithm algorithm)
{
    using (var stream = new BufferedStream(File.OpenRead(fileName), 1000000))
    {
        return BitConverter.ToString(algorithm.ComputeHash(stream)).Replace("-", string.Empty);
    }
}

public static string GetChecksum(Stream stream, HashAlgorithm algorithm)
{
    using (stream)
    {
        return BitConverter.ToString(algorithm.ComputeHash(stream)).Replace("-", string.Empty);
    }
}

谁能解释一下这两者有什么区别。最终这两种方法都解析为 GetChecksum 方法中的 Stream

Answer 1

如果您要对流进行哈希处理，您需要在计算哈希之前将流的当前位置设置为 0。

file.InputStream.Seek(0, SeekOrigin.Begin);

对我来说，这是扩展方法的好地方，例如:

//compute hash using extension method:
string checksumMd5    = file.InputStream.GetMD5hash();

该类支持哪些:

using System;
using System.IO;

public static class Extension_Methods
{

    public static string GetMD5hash(this Stream stream)
    {
        stream.Seek(0, SeekOrigin.Begin);
        using (var md5Instance = System.Security.Cryptography.MD5.Create())
        {
            var hashResult = md5Instance.ComputeHash(stream);
            stream.Seek(0, SeekOrigin.Begin);
            return BitConverter.ToString(hashResult).Replace("-", "").ToLowerInvariant();
        }
    }

}