mirror of
https://git.tartarus.org/simon/putty.git
synced 2025-03-16 12:03:03 -05:00
5b14abc30e
I've written a new standalone test program which incorporates all of PuTTY's crypto code, including the mp_int and low-level elliptic curve layers but also going all the way up to the implementations of the MAC, hash, cipher, public key and kex abstractions. The test program itself, 'testcrypt', speaks a simple line-oriented protocol on standard I/O in which you write the name of a function call followed by some inputs, and it gives you back a list of outputs preceded by a line telling you how many there are. Dynamically allocated objects are assigned string ids in the protocol, and there's a 'free' function that tells testcrypt when it can dispose of one. It's possible to speak that protocol by hand, but cumbersome. I've also provided a Python module that wraps it, by running testcrypt as a persistent subprocess and gatewaying all the function calls into things that look reasonably natural to call from Python. The Python module and testcrypt.c both read a carefully formatted header file testcrypt.h which contains the name and signature of every exported function, so it costs minimal effort to expose a given function through this test API. In a few cases it's necessary to write a wrapper in testcrypt.c that makes the function look more friendly, but mostly you don't even need that. (Though that is one of the motivations between a lot of API cleanups I've done recently!) I considered doing Python integration in the more obvious way, by linking parts of the PuTTY code directly into a native-code .so Python module. I decided against it because this way is more flexible: I can run the testcrypt program on its own, or compile it in a way that Python wouldn't play nicely with (I bet compiling just that .so with Leak Sanitiser wouldn't do what you wanted when Python loaded it!), or attach a debugger to it. I can even recompile testcrypt for a different CPU architecture (32- vs 64-bit, or even running it on a different machine over ssh or under emulation) and still layer the nice API on top of that via the local Python interpreter. All I need is a bidirectional data channel.