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c#hashcryptographymd5cryptographic-hash-function
Blankman
Blankman

Reputation: 266900

Converting a md5 hash byte array to a string

How can I convert the hashed result, which is a byte array, to a string?

byte[] bytePassword = Encoding.UTF8.GetBytes(password);

using (MD5 md5 = MD5.Create())
{
    byte[] byteHashedPassword = md5.ComputeHash(bytePassword);
}

I need to convert byteHashedPassword to a string.

Upvotes: 94

Views: 103174

Answers (9)

Jake Walden
Jake Walden

Reputation: 533

I'm late to the party, but here is a faster version than Philippe Leybaert's answer:

public static class BytesToHexStringHelpers
{       
    public static string ToHexString(this byte[] bytes)
        => ToHexString(bytes, 0, bytes.Length);
        
    public static string ToHexString(this byte[] bytes, int startIndex, int length)
    {
        const string HexadecimalUppercase = "0123456789ABCDEF";
        
        var hexChars = new char[length * 2];
        var hexCharsIndex = 0;
        var endIndex = startIndex + length;
        
        for (var bytesIndex = startIndex; bytesIndex < endIndex; bytesIndex++)
        {
            hexChars[hexCharsIndex++] = HexadecimalUppercase[bytes[bytesIndex] >> 4];
            hexChars[hexCharsIndex++] = HexadecimalUppercase[bytes[bytesIndex] & 0xF];
        }

        return new string(hexChars);
    }
}

In .NET5 and above System.Convert.ToHexString(...) is probably best.

Upvotes: 0

Dazfl
Dazfl

Reputation: 775

I know this is an old question, but I thought I would add you can use the built-in methods (I'm using .NET 6.0):

  • Convert.ToBase64String(hashBytes); (Others have already mentioned this)
  • Convert.ToHexString(hashBytes);

Upvotes: 4

garryp
garryp

Reputation: 5766

For anyone interested a Nuget package I created called CryptoStringify allows you to convert a string to a hashed string using a nice clean syntax, without having to play around with byte arrays:

using (MD5 md5 = MD5.Create())
{
    string strHashedPassword = md5.Hash(password);
}

It's an extension method on HashAlgorithm and KeyedHashAlgorithm so works on SHA1, HMACSHA1, SHA256 etc too.

https://www.nuget.org/packages/cryptostringify

Upvotes: 0

Simon_Weaver
Simon_Weaver

Reputation: 145880

If you're in the 'Hex preference' camp you can do this. This is basically a minimal version of the answer by Philippe Leybaert. 

string.Concat(hash.Select(x => x.ToString("X2")))

B1DB2CC0BAEE67EA47CFAEDBF2D747DF

Upvotes: 24

GrayWizardx
GrayWizardx

Reputation: 21111

I always found this to be the most convenient:

string hashPassword = BitConverter.ToString(byteHashedPassword).Replace("-","");

For some odd reason BitConverter likes to put dashes between bytes, so the replace just removes them.

Update: If you prefer "lowercase" hex, just do a .ToLower() and boom.

Do note that if you are doing this as a tight loop and many ops this could be expensive since there are at least two implicit string casts and resizes going on.

Upvotes: 70

Eric Petroelje
Eric Petroelje

Reputation: 60498

Well, you could use the string constructor that takes bytes and an encoding, but you'll likely get a difficult to manage string out of that since it could contain lots of fun characters (null bytes, newlines, control chars, etc)

The best way to do this would be to encode it with base 64 to get a nice string that's easy to work with:

string s = Convert.ToBase64String(bytes);

And to go from that string back to a byte array:

byte[] bytes = Convert.FromBase64String(s);

Upvotes: 7

AxelEckenberger
AxelEckenberger

Reputation: 16926

Well as it is a hash, it has possibly values that cannot be shown in a normal string, so the best bet is to convert it to Base64 encoded string.

string s = Convert.ToBase64String(bytes);

and use 

byte[] bytes = Convert.FromBase64(s);

to get the bytes back.

Upvotes: 10

Philippe Leybaert
Philippe Leybaert

Reputation: 171734

   public static string ToHex(this byte[] bytes, bool upperCase)
    {
        StringBuilder result = new StringBuilder(bytes.Length*2);

        for (int i = 0; i < bytes.Length; i++)
            result.Append(bytes[i].ToString(upperCase ? "X2" : "x2"));

        return result.ToString();
    }

You can then call it as an extension method:

string hexString = byteArray.ToHex(false);

Upvotes: 91

David
David

Reputation: 34543

You can use Convert.ToBase64String and Convert.FromBase64String to easily convert byte arrays into strings.

Upvotes: 31

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