Como chamar uma função no meu sistema?

function Crypt(Action, Src: String): String;
Label Fim;
var KeyLen : Integer;
  KeyPos : Integer;
  OffSet : Integer;
  Dest, Key : String;
  SrcPos : Integer;
  SrcAsc : Integer;
  TmpSrcAsc : Integer;
  Range : Integer;
begin
  if (Src = ´´) Then
  begin
    Result:= ´´;
    Goto Fim;
  end;
  Key :=´YUQL23KL23DF90WI5E1JAS467NMCXXL6JAOAUWWMCL0AOMM4A4VZYW9KHJUI2347EJHJKDF3424SKLK3LAKDJSL9RTIKJ´;
  Dest := ´´;
  KeyLen := Length(Key);
  KeyPos := 0;
  SrcPos := 0;
  SrcAsc := 0;
  Range := 256;
  if (Action = UpperCase(´C´)) then
  begin
    Randomize;
    OffSet := Random(Range);
    Dest := Format(´¬1.2x´,[OffSet]);
    for SrcPos := 1 to Length(Src) do
    begin
      Application.ProcessMessages;
      SrcAsc := (Ord(Src[SrcPos]) + OffSet) Mod 255;
      if KeyPos < KeyLen then KeyPos := KeyPos + 1 else KeyPos := 1;
      SrcAsc := SrcAsc Xor Ord(Key[KeyPos]);
      Dest := Dest + Format(´¬1.2x´,[SrcAsc]);
      OffSet := SrcAsc;
    end;
  end
  Else if (Action = UpperCase(´D´)) then
  begin
    OffSet := StrToInt(´$´+ copy(Src,1,2));
    SrcPos := 3;
  repeat
    SrcAsc := StrToInt(´$´+ copy(Src,SrcPos,2));
    if (KeyPos < KeyLen) Then KeyPos := KeyPos + 1 else KeyPos := 1;
    TmpSrcAsc := SrcAsc Xor Ord(Key[KeyPos]);
    if TmpSrcAsc <= OffSet then TmpSrcAsc := 255 + TmpSrcAsc - OffSet
    else TmpSrcAsc := TmpSrcAsc - OffSet;
    Dest := Dest + Chr(TmpSrcAsc);
    OffSet := SrcAsc;
    SrcPos := SrcPos + 2;
  until (SrcPos >= Length(Src));
  end;
  Result:= Dest;
  Fim:
end;