Generate SHA1 Hash in Portable Class Library

Question

I\'m trying to build a portable class library that generates OAuth urls for other classes/applications to use. This class library using OAuth has to be a portable class libr

Answer 1

Well I needed this too recently and I found much easier to take SHA1 implementation from HashLib : http://hashlib.codeplex.com/

Mono implementation have some far-going dependencies (localization of exceptions, etc.), while from HashLib you need only to copy few files without any changes in them:

Converters.cs
Hash.cs
HashBuffer.cs
HashCryptoNotBuildIn.cs
HashResult.cs
IHash.cs
SHA0.cs
SHA1.cs

55 KB of code total, so nothing too heavy.

Answer 2

The SHA-1 Wikipedia article contains pseudocode that you could use as a guideline for your own implementation. But, as always with cryptographic functions, I strongly advise to use a tried and tested implementation.

Assuming you want a SHA-256 implementation, you can find one in BouncyCastle, which is available in source code form. The relevant class there is called Org.BouncyCastle.Crypto.Digests.Sha256Digest (here's its source).

Answer 3

This worked for me when I had to achieve the same outcome. You can do this with SHA512 and others too.

using System.Security.Cryptography;

public static string HashSHA1(this string value)
{
    using (var sha = SHA1.Create())
    {
       return Convert.ToBase64String(sha.ComputeHash(System.Text.Encoding.UTF8.GetBytes(value)));
    }
}

Code cited from: https://xamarinhelp.com/cryptography-in-xamarin-forms/