Add Parsec authentication plugin implementation.

Author: bgrainger

src/MySqlConnector.Authentication.Ed25519/ParsecAuthenticationPlugin.cs

@@ -0,0 +1,49 @@
+using System;
+using System.Threading;
+
+namespace MySqlConnector.Authentication.Ed25519;
+
+/// <summary>
+/// Provides an implementation of the Parsec authentication plugin for MariaDB.
+/// </summary>
+public sealed class ParsecAuthenticationPlugin : IAuthenticationPlugin2
+{
+	/// <summary>
+	/// Registers the Parsec authentication plugin with MySqlConnector. You must call this method once before
+	/// opening a connection that uses Parsec authentication.
+	/// </summary>
+	public static void Install()
+	{
+		if (Interlocked.CompareExchange(ref s_isInstalled, 1, 0) == 0)
+			AuthenticationPlugins.Register(new ParsecAuthenticationPlugin());
+	}
+
+	/// <summary>
+	/// Gets the authentication plugin name.
+	/// </summary>
+	public string Name => "client_parsec"; // TODO: Update with correct name from parsec-spec.txt
+
+	/// <summary>
+	/// Creates the authentication response.
+	/// </summary>
+	public byte[] CreateResponse(string password, ReadOnlySpan<byte> authenticationData)
+	{
+		// TODO: Implement Parsec authentication protocol
+		throw new NotImplementedException();
+	}
+
+	/// <summary>
+	/// Creates the Parsec password hash.
+	/// </summary>
+	public byte[] CreatePasswordHash(string password, ReadOnlySpan<byte> authenticationData)
+	{
+		// TODO: Implement Parsec password hashing
+		throw new NotImplementedException();
+	}
+
+	private ParsecAuthenticationPlugin()
+	{
+	}
+
+	private static int s_isInstalled;
+}