Girotel for linux project page

girotel online using perl

see this page for some information on how to access the new girotel online service of the postbank using a small perl module.

Here I describe how to decode protocols used by sites which hide all communications using SSL

protocol information

By running girotel for dos using dos emu 0.99.11 with this patch, or girotel for windows using wine 990314 with this patch I can log the communication between the girotel client and server. I process it with this C program, to get output looking like this.

In this example some information is modified to prevent abuse. So some fields in it may be inconsistent.

The wine patch contains the patch by Rein kLazes. Both patches add a serial port logging module. The wine patch also includes a patch to correct the unget handling.

A summary of the protocol as far as I have decoded it by now can be found here.

the authentication protocol

Some work still needs to be done here. Girotel has five locations where it uses some kind of authentication protocl:
  1. the initial logon, where your girotel number and girotel code are transmitted in plaintext.
  2. the authentication using your GIN number
  3. when changing your GIN number
  4. when authorising a batch of transactions with a TAN number
  5. when invalidating your list of TAN numbers
From the debugging remarks left in the DLL I assume it uses DES for some of these protocols. I don not yet know how exactly this is done. looking at a disassembly of gtwin.exe I concluded that a debug flag is present in some of the objects that are being operated upon.

links to other sites

de postbank

girotel onder linux