OOAPI-SSL/TLS (Was: Simple SSL/TLS - Some Questions)

[Hadmut Danisch]

On Fri, Oct 03, 2003 at 05:55:25PM +0100, Jill Ramonsky wrote:
> Having been greatly encouraged by people on this list to go ahead with a 
> new SSL implementation, 

That's a pretty good idea, I also encourage you (and volunteer to
support).


> The main 
> point of confusion/contention right now seem to be (1) should it be in C 
> or C++?,


I definitely vote for C++ for several reasons. You already mentioned 
plenty of reasons yourself, the security advantages of C++. But be
warned: In contrast to modern scripting languages C++ is not
automatically immune against buffer overruns etc. It takes some
discipline to have a good programming style in C++.

The main advantage I see is the oportunity to have a good, 
object oriented design of the API to give an example of a 
good and usable Crypto API.

Everyone here has his own favourite language, I meanwhile prefer
Ruby. I had to write a CA some months ago and didn't find a good
language with SSL and Certificate management support, except for 
Ruby. Michal Rokos <m.rokos at sh.cvut.cz> was currently writing the
glue code to use the openssl library with ruby, and I found it 
very comfortable to use SSL from a scripting language. It was 
however a big heap of debugging, reading the openssl API and source
code, discussing requirements with Michal, ask him for extensions
etc., since it is quite difficult, to implement all features of 
openssl, and many of them are not logical. This project showed 
the shortcomings of openssl, it is not really a usable and complete
software. This causes insecurity, because it is too difficult for
application writers to use it and to support all features.


I'd therefore propose the following:


To design two (ore more) object oriented APIs for

- cryptographic primitives
- non-communication oriented functions (key and certificate
  management, S/MIME message handling, ...) 
- communication oriented functions (SSL/TLS)


but to not stick too tight to C++. The design must be applicable 
to all modern object oriented languages.


Then do a C++ implementation of the API (spell: header files) and
see, whether this is possible without tricks. Also have the API 
defined in other languages such as Python, Ruby, Java,...

Take care that the design is easy to read, easy to understand, 
easy to debug. Make use of object oriented design where possible.


Now implement the library itself in C++, while others write
the glue code for other languages simultaneously.


As a result, there will be a language-independend object-oriented
Meta-API, describing the library virtually for all languages.
For every supported language there is a "translated API" of this
and a library to use. For C++, this is a genuine library, for
other languages this will be glue code + the C++ library.




This would be a step to bring secure programming a step forward
towards modern programming, and to ease and support use of 
SSL/TLS/... 

I am currently quite happy with the way Michal Rokos wrapped 
openssl into an object oriented API, but it would be good to 
have this in more languages, it still allows improvements and
is still incomplete.


regards
Hadmut





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