great

The number one reason is that I've never liked C++. I get on with C much better.

C++ programmers can pretty much read and use C code with little problem. C++ code is not so easy for solely C programmers. Not only can the library be used by C programmers, it can be written by C programmers that don't get on with C++.

And implementing OOP features in C is not as hard as it sounds once you know how.

But yes, that's a common question.

+1

If he manages to pull this off without a dependency on OpenSSL, his code is going to be able to run on my credit card machines.

From the perspective of being educational, I have absolutely no problem with people reimplementing code. They may stumble upon bugs, and even a partial implementation can have niche purposes (for example only the networking code for a crawler, or fast blockchain manipulation code for rescanning addresses).

That said, trying to understand existing code also has great educational value; in particular when you're trying to improve things, because that confronts you with things you thought you understood but didn't. In my opinion, this is a better way for helping the community than by starting from scratch - that just takes longer before it is useful.

Looks like your writing this to work on 8-bit CPUs? This may be very useful if you can keep it C-only and 8-bit compatible... Single chip embedded bitcoin client anyone?

This library aims to have zero dependencies except the standard C library making it small and easily portable. This doesn't mean I will reinvent the wheel in every single case. There are many open source implementations of the things my library will need. I can adapt these tried and tested algorithms to suit the specific needs of this library. In some cases it may be more or less copy and paste and in other cases it may require tweaks or substantial modifications.

At the moment I'm implementing specialist functions that include operations between a bignum and an 8 bit integer. This is for the base-58 encoder/decoder. If anyone knows a better solution to the base-58 stuff, please tell me or feel free to work on it yourself. When I'll be going operations between two bignums it should be simple to derive my code from bignum libraries and then I can derive the cryptography code from open-source libraries such as OpenSSL too.


Well wouldn't that be interesting. You would need an implementation of standard library features including dynamic memory allocation but I plan absolutely no additional dependencies other than the standard C library. Of-course, feel free to contribute anything, including ideas.


Thanks. I am doing this largely to learn as well as to create something functional. The images you have made a pretty nice. Would I be able to use them in my documentation? I do hope to build a nice documentation for my library.

For the next few days I'll be busy with other things but I'll when I'm back to this library I hope to sort of the base-58 code and also modify the OOP so that the virtual function tables are initialised at compile time which makes more sense.


The library should be compilable with C compilers providing C99 with the standard library is supported (At least everything the library uses). Perhaps the library will need minor tweaks for compilers that aren't compatible with some features in C99 but that's not going to cause many headaches I sure. The biggest headache would be to implement the standard library features for microcontrollers with no out of the box standard C library support.

But are you saying some 8-bit architectures come with compilers that only allow 8 bit types? That would be pretty rubbish. The compilers should support up-to 64 bit integer types (int64_t). I believe long long types should be at least 64 bits so a compiler that keeps to the C specification properly should support it.

If anyone understands microcontrollers well and can advise on how the library can be designed with microcontroller portability in mind, please share your knowledge.

Under the images I can put "Pictures created by Alan Reiner, developer of Bitcoin Armory (http://bitcoinarmory.com/)"?

I'm hoping following bitcoinj will also help (It's very easy to read), the issue is that bitcoinj doesn't implement everything so I'll have to look into other code that does implement things like the script properly. The C++ client has the code but it harder to read. Documentation no doubt helps me understand what I'm doing rather than do a piece by piece port, so I can make better code.

In order to have a super-lean runtime and dev environment, for example...

Would people be more universally happy if my library required developers using the library to pass cryptographic functionality to the library using function pointers? That way people can use whatever cryptography library they like that matches their needs, and my library will focus on everything else unique to bitcoin.

Good idea?