There has been much discussion recently on whether an API interface should be made available for GPG. Some of this has revolved around whether it is possible to easily implement such functionality. I have chosen to devote my DCN assignment two to this question.

The following documents constitute my submission:

• A log of the GPG API related threads on the gpg-devel mailing list, including comments from myself
• Some patches to the GPG source code to implement a proof of concept API function. I have chosen the decrypt function as it seems to be one of the more commonly used and therefore most useful functions. To make these changes I have had to modify some of the GPG source code, which is what the patches are. The patches are also available for easy download:
  • The differences file (signed)
  • api.c (signed)
  • api.h (signed)
  • and main.c (signed), which is added to the user interface code. This is needed so that main() is not imported into the C library that the API produces.
• A commentary on the GPG source code that was developed while working on this API functionality. This is by no means complete, but it aids in comprehension of the GPG code somewhat. This has also been included the in patches above and the modified source code below to keep it all in one place. This link is merely to the commented files, to minimse the amount of digging around required to see what I have added.
• There is also a beautified version of the original 1.0.3 code, and the modified 1.0.3 code.
• And finally, here is some documentation proving that the proof of concept code works (and explaining how you can go about testing it yourself).