Skip to content
Switch branches/tags

Latest commit


Git stats


Failed to load latest commit information.
Latest commit message
Commit time
This is Gwenhywfar, a multi-platform helper library for networking and
security applications and libraries. 
It is used by 
 - Libchipcard (, 
 - OpenHBCI2 (, 
 - Simthetic, the simulation tool (
 - AqBanking/AqHBCI (
 - and others by using one of the projects above


This library is written in C, and it follows the object-oriented
programming paradigm for most of its parts.  The header files can
directly be used from C++, too.

Gwenhywfar includes the following features:

- Basic Data types for binary buffers, ring buffers, linked lists, 
  error objects, string lists (src/base/), buffered IO operations (src/io/)

- Macros for typesafe list management

- OS abstraction functions for directory and Internet address handling
  and library loading (src/os/)

- Networking functions which allow to manage many connections to be used
  economically even in single threaded applications

- High-level functions for parsing files with a simplified "XML-like"
  format and accessing them like a hierarchical database (src/parser/)
  It is able to process valid XML files, too.

- High-level cryptographic functions on top of OpenSSL functionality

- Support for interprocess communication (HTTP on top of SSL or plain
  TCP/UDP sockets, with or without certificates for clients and/or servers)

- A tool to generate simple data containers from XML files. It automatically
  generates getters, setters, constructor, destructor, deep-copy function,
  usage counter handling, modification tracking, functions for reading from 
  and writing to GWEN_DBs (used by AqBanking to create the transaction class)


- GnuTLS >= 1.4 (>=2.0.1 recommended)
- libgcrypt (>=1.2.0)


Gwenhywfar is being developed on Linux. But the following platforms are also

- Windows (98, NT and newer; for using this library from Microsoft
  Visual Studio C please see the explanations in test/README.MSVC)

- FreeBSD   
- Linux     (i386, amd64, alpha)
- Mac OS-X  
- NetBSD    (untested, but most likely to work)
- OpenBSD   (untested, but most likely to work)
- SunOS 5.9 (compiles, untested, but most likely to work)

On Windows, an .exe setup program is provided, created with the Inno
Setup Compiler .


According to Debian Gwen runs on the following platforms:
- alpha
- amd64
- arm
- hppa
- i386
- ia64
- m68k
- mips
- mipsel
- powerpc
- s390
- sparc

Environment Variables


This integer variable tells gwen whether (and how) to print the memory
debugger statistic. This only works for sources compiled with the defined
- "0" shows ALL listed objects
- "1" only shows those objects whose count is not 0


If this environment variable exists the SSL code will append data received
via an SSL connection to "/tmp/read.bin" and append data sent via an SSL
connection to /tmp/written.bin".


If this environment variable is set, the SSL code will initialize the GnuTLS
library with the provided cipher priority list.  If this environment variable
is unset, the default cipher priority list of the GnuTLS library is being used.

For the exact format of the cipher priority list and its default, please
consult the GnuTLS documentation, section "Priority strings":

Registry Keys

On Windows platforms Gwen uses some keys below HKEY_CURRENT_USER
to store information about file/folder locations. The keys are set
in the Inno Setup file gwenhywfar.iss, so please check the
[Registry] section in for the authoritative
source of available registry keys.

Complete path to the folder containing GWENs DBIO plugins.
(and some more keys. See


The documentation can be found in the header files. Many header 
files already include extensive comments in doxygen-format (however some 
For a more or less complete API documentation use the command
"make srcdoc"
You will need the tool doxygen for this command to run.


For questions about this library please ask on the mailing list of the
AqBanking project aqbanking-devel (subscriber-only, please subscribe
since this is where the author(s) hang out. 


This library is being written by and is being maintained by Martin
Preuss <>. 

I also wish to thank Christian Stimming <> for his
contributions and for adding MSVC support to Gwen (thus making Gwen completely
available on Windows).


The name of this library was chosen to honour a very special person ;-)
(that should suffice as an explanation)

Hamburg, Germany 2021/09/30