Zork GCM setup

This should be straightforward for C developers. However, there are a few things worth noting:

If your architecture does not have BYTE_ORDER defined (some embedded platforms may not), then you need to set it, along with values of BIG_ENDIAN and LITTLE_ENDIAN.
There are multiple APIs for different internal table sizes. We recommend smaller table sizes. 256 byte tables performs more than acceptably for pretty much any application.

There are Python bindings for anyone who wants to use this from Python programs. Just compile with -D PYTHON_BINDINGS into a .so file. If you use Python's distutils you can create a setup.py file as such:

from distutils.core import setup, Extension

setup(name='PyGCM',
      version='0.9.5',
      description='Python GCM bindings',
      author='John Viega'
      author_email='viega@zork.org',
      url='http://www.cryptobarn.com/gcm',
      ext_modules=[Extension('GCM', ['prp.c', 'gcm.c'],
                             extra_compile_args=['-Wno-strict-prototypes', '-DPYTHON_BINDINGS'],
                             )],
      )

And then run "python setup.py install"

If sizeof(unsigned int) != 4 or sizeof(unsigned long long) != 8, then you will need to change the typedefs for uint64 and uint32 in gcm.h to appropriate values. Note that most compilers provide an emulated 64-bit type. Using this type helps speed things up on 64-bit platforms. If your platform doesn't have a 64-bit type (emulated or no), we provide an alternate interoperating implementation in gcm32.h and gcm32.c.

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