Adds Argon2 for password protection (#123)

Projects/Scripts/Accounting/Security/AccountSecurity.cs

@@ -0,0 +1,45 @@
+using System;
+
+namespace Server.Accounting.Security
+{
+  public enum PasswordProtectionAlgorithm
+  {
+    // Obsolete algorithms. These are not secure!
+    // They are included for password upgrades only.
+    None,
+    MD5,
+    SHA1,
+
+    // Support algorithms
+    PBKDF2,
+    Argon2 // Recommended algorithm for real security.
+  }
+
+  public static class AccountSecurity
+  {
+    // TODO: Put it in a configuration
+    public const PasswordProtectionAlgorithm AlgorithmName = PasswordProtectionAlgorithm.Argon2;
+
+    public static readonly IPasswordProtection CurrentPasswordProtection = GetPasswordProtection(AlgorithmName);
+
+    public static void Configure()
+    {
+      if (AlgorithmName < PasswordProtectionAlgorithm.PBKDF2)
+        throw new Exception($"Security: {AlgorithmName} is obselete and not secure. Do not use it.");
+    }
+
+    public static IPasswordProtection GetPasswordProtection(PasswordProtectionAlgorithm algorithm)
+    {
+      var passwordProtection = algorithm switch
+      {
+        PasswordProtectionAlgorithm.MD5 => MD5PasswordProtection.Instance,
+        PasswordProtectionAlgorithm.SHA1 => SHA1PasswordProtection.Instance,
+        PasswordProtectionAlgorithm.PBKDF2 => PBKDF2PasswordProtection.Instance,
+        PasswordProtectionAlgorithm.Argon2 => Argon2PasswordProtection.Instance,
+        _ => null
+      };
+
+      return passwordProtection;
+    }
+  }
+}