The following files were taken from gnulib.

  * gc-pbkdf2-sha1.c
  * hmac-sha1.c
  * hmac.h
  * memxor.c
  * memxor.h
  * sha1.c
  * sha1.h

I added gc-pbkdf2-sha1.h to have a nice header file to use.

Some files were slightly modified to remove the gnulib dependency
and to make them compile using MSVC.

  - Marc Maurer, March 20, 2010