如何从文本文件创建 MD5 哈希摘要？

Question

我想使用 C# 创建文本文件的 MD5 哈希值。我怎样才能做到这一点？

更新：感谢大家的帮助。我最终决定使用以下代码 -

// Create an MD5 hash digest of a file
public string MD5HashFile(string fn)
{            
    byte[] hash = MD5.Create().ComputeHash(File.ReadAllBytes(fn));
    return BitConverter.ToString(hash).Replace("-", "");            
}

Answer 1

这是我目前正在使用的例程。

    using System.Security.Cryptography;

    public string HashFile(string filePath)
    {
        using (FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.Read))
        {
            return HashFile(fs);
        }
    }

    public string HashFile( FileStream stream )
    {
        StringBuilder sb = new StringBuilder();

        if( stream != null )
        {
            stream.Seek( 0, SeekOrigin.Begin );

            MD5 md5 = MD5CryptoServiceProvider.Create();
            byte[] hash = md5.ComputeHash( stream );
            foreach( byte b in hash )
                sb.Append( b.ToString( "x2" ) );

            stream.Seek( 0, SeekOrigin.Begin );
        }

        return sb.ToString();
    }

Answer 2

简短而切题。 filename 是您的文本文件的名称：

using (var md5 = MD5.Create())
{
    return BitConverter.ToString(md5.ComputeHash(File.ReadAllBytes(filename))).Replace("-", "");
}

Answer 3

这可以通过带有重载的 GetHashCode 来实现，允许传递 filePath、StreamReader 或 Stream：

private static string GetHashCode(string filePath, HashAlgorithm cryptoService = null)
    => GetHashCode(fStream: new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite), cryptoService);

private static string GetHashCode(StreamReader fileStreamReader, HashAlgorithm cryptoService = null)
    => GetHashCode(fileStreamReader.BaseStream, cryptoService);


/// <summary>
/// Compute hash code for file.
/// </summary>
/// <param name="fStream"></param>
/// <param name="cryptoService">This can be either MD5, SHA1, SHA256, SHA384 or SHA512</param>
/// <returns>Hash string</returns>
private static string GetHashCode(Stream fStream, HashAlgorithm cryptoService = null)
{

    // create or use the instance of the crypto service provider
    // this can be either MD5, SHA1, SHA256, SHA384 or SHA512
    using (cryptoService ??= System.Security.Cryptography.SHA512.Create())
    {
        using var tmpStream = fStream;
        var hash = cryptoService.ComputeHash(tmpStream);
        var hashString = Convert.ToBase64String(hash);
        return hashString.TrimEnd('=');
    }
} // method

用法：

WriteLine("Default Sha512 Hash Code   : {0}", GetHashCode(FilePath));

或者：

WriteLine("MD5 Hash Code   : {0}", GetHashCode(FilePath, new MD5CryptoServiceProvider()));
WriteLine("SHA1 Hash Code  : {0}", GetHashCode(FilePath, new SHA1CryptoServiceProvider()));
WriteLine("SHA256 Hash Code: {0}", GetHashCode(FilePath, new SHA256CryptoServiceProvider()));
WriteLine("SHA384 Hash Code: {0}", GetHashCode(FilePath, new SHA384CryptoServiceProvider()));
WriteLine("SHA512 Hash Code: {0}", GetHashCode(FilePath, new SHA512CryptoServiceProvider()));

Answer 4

这是一个不需要将整个文件读入内存的 .NET 标准版本：

    private byte[] CalculateMD5OfFile(FileInfo targetFile)
    {
        byte[] hashBytes = null;
        using (var hashcalc = System.Security.Cryptography.MD5.Create())
        {
            using (FileStream inf = targetFile.OpenRead())
                hashcalc.ComputeHash(inf);
            hashBytes = hashcalc.Hash;
        }
        return hashBytes;
    }

您可以使用上面显示的方法将 byte[] 数组转换为字符串。另外：您可以将第三行中的“MD5”更改为SHA1、SHA256等来计算其他哈希值。