Generate Android App Hash Key in Xamarin using Package Name and Keystore Signature

AppHashKeyGenerator.cs

// move to the class global level
using Android.Util;
using Java.Security;
using Java.Util;
using System.Text;
// move to the class global level

private static string HASH_TYPE = "SHA-256";
private static int NUM_HASHED_BYTES = 9;
private static int NUM_BASE64_CHAR = 11;

/// <summary>
/// Generate App hash key using package 
/// name and keystore hex signature
/// </summary>
/// <param name="packageName"></param>
/// <param name="keystoreHexSignature"></param>
/// <returns></returns>
public static string GetAppHashKey
	(String packageName, String keystoreHexSignature)
{
	string appInfo = packageName + " " + keystoreHexSignature;
	try
	{
		MessageDigest messageDigest = MessageDigest.GetInstance(HASH_TYPE);
		messageDigest.Update(Encoding.UTF8.GetBytes(appInfo));
		byte[] hashSignature = messageDigest.Digest();

		hashSignature = Arrays.CopyOfRange (hashSignature, 0, NUM_HASHED_BYTES);
		string base64Hash = Android.Util.Base64.EncodeToString
		(hashSignature, Base64Flags.NoPadding | Base64Flags.NoWrap);
		base64Hash = base64Hash.Substring(0, NUM_BASE64_CHAR);

		return base64Hash;
	}
	catch (NoSuchAlgorithmException e)
	{
		return null;
	}
}