Added ValidAuthenticationHash and SetDefaultAuthenticationHashClass

In order to make upgrading from DEC 5.x easier.

Author: Markus Humm

Source/DECHashAuthentication.pas

@@ -935,6 +935,29 @@   TDECHashAuthenticationClass = class of TDECHashAuthentication;
   /// </summary>
   TDECHashExtendedClass = class of TDECHashExtended;
 
+  /// <summary>
+  /// Returns the passed class type if it is not nil. Otherwise the class type
+  /// of the TFormat_Copy class is being returned.
+  /// </summary>
+  /// <param name="FormatClass">
+  /// Class type of a formatting class like TFormat_HEX or nil, if no formatting
+  /// is desired.
+  /// </param>
+  /// <returns>
+  /// Passed class type or TFormat_Copy class type, depending on FormatClass
+  /// parameter value.
+  /// </returns>
+  function ValidAuthenticationHash(HashClass: TDECHashClass): TDECHashAuthenticationClass;
+  /// <summary>
+  ///   Defines which hash class to return by ValidAuthenticationHash if passing
+  ///   nil to that
+  /// </summary>
+  /// <param name="HashClass">
+  ///   Class type of a Hash class to return by ValidAuthenticationHash if
+  ///   passing nil to that one. This parameter should not be nil!
+  /// </param>
+  procedure SetDefaultAuthenticationHashClass(HashClass: TDECHashClass);
+
 implementation
 
 uses
@@ -954,6 +977,17 @@ implementation
   ///   not supported.
   /// </summary>
   sCryptIDNotRegistered = 'No class for crypt ID %s registered';
+  /// <summary>
+  ///   Exception message used when no default class has been defined
+  /// </summary>
+  sAuthHashNoDefault    = 'No default authentication hash class has been registered';
+
+var
+  /// <summary>
+  ///   Hash class returned by ValidAuthenticationHash if nil is passed as
+  ///   parameter to it
+  /// </summary>
+  FDefaultAutheticationHashClass: TDECHashAuthenticationClass = nil;
 
 class function TDECHashAuthentication.IsPasswordHash: Boolean;
 begin
@@ -1656,4 +1690,22 @@ function TDECPasswordHash.IsValidPassword(Password        : TBytes;
   Result := false;
 end;
 
+function ValidAuthenticationHash(HashClass: TDECHashClass): TDECHashAuthenticationClass;
+begin
+  if Assigned(HashClass) then
+    Result := TDECHashAuthenticationClass(HashClass)
+  else
+    Result := FDefaultAutheticationHashClass;
+
+  if not Assigned(Result) then
+    raise EDECHashException.CreateRes(@sAuthHashNoDefault);
+end;
+
+procedure SetDefaultAuthenticationHashClass(HashClass: TDECHashClass);
+begin
+  Assert(Assigned(HashClass), 'Do not set a nil default hash class!');
+
+  FDefaultAutheticationHashClass := TDECHashAuthenticationClass(HashClass);
+end;
+
 end.