add verifying signed message, using pubkey recovery

[rubensayshi]

Work in Progress

I ported the code for pubkey recovery from bitcoin core using ctypes, the same way as the other code is written.

The VerifyMessage (and BitcoinMessage class) are still in the test_signverify_message.py because I have no idea where you would want these to go? please let me know where you want me to put them

I'm not entirely sure about the CPubKey.recover_compact, as a python dev I'd say it should be a @classmethod (like it is now) but to match the bitcoin core code (which is what you've been doing) should it be different?

tested against py2.7 and py3.4, to test it against libeay I have to run it on windows I guess, or is it 100% certain that everything 'just works'?

PS. is there any particular reason for not having travis-ci setup to run the tests on the various python versions?

[rubensayshi]

okay, seem to have it working now except I keep running into some odd thing where if _ssl.BN_bin2bn stops when it runs into x00, eg;
b'\x00\xeb\xbb\x00\x17\x0c\x93(\xd4U\xfd\xc7\xfe\x1d\xf9&\xf9\xff\x1e\x8dB\xc8\x98~\xe1Y\x8e3g\xe4\x88\x0c\x90' becomes b'\xeb\xbb'
and
b'\x00\xc3\xd7!7\x01\x99\xcd%+\xef\xcd+n\xac\x00\x0b\x82\xdb\xb72+\xb4\xe6]\x80\xeb\xc0s\x99\x94"\xe3' becomes b'\xc3\xd7!7\x01\x99\xcd%+\xef\xcd+n\xac

Maybe @petertodd you can help me with this because tbh I this is the first time for be using this stuff and I have no clue why this happens.

PS. I made a DERSignature(ImmutableSerializable) class;

1. idk where to put it
2. maybe you don't like it and just prefer reusing the code in IsLowDERSignature to decode the signature?
3. should I change it so that IsLowDERSignature uses it too?

[petertodd]

FWIW, I'm travelling right now and am pretty busy until the MIT Bitcoin Expo is over; I'll try to get to this when I get back after that.

Thanks!

[rubensayshi]

@petertodd I fixed the issue with the null bytes, if you could tell me where (which files) you'd prefer these things to go then this stuff should be ready:

• class BitcoinMessage(ImmutableSerializable)
• def SignMessage(key, message)
• def VerifyMessage(address, message, sig)

[petertodd]

So bitcoin signatures aren't consensus critical, so rather than putting them in bitcoin.core.signature, let's put that functionality in bitcoin.signature instead. As for the code you added to bitcoin.core.key though... meh, leave it there for now; this can be cleaned up later.

[rubensayshi]

@petertodd I've been slacking lately, sorry for that, I want / need to pick up this PR ...

I'll move bitcoin.core.signature to bitcoin.signature, the classes I listed before are currently in test_signverify_message.py, normally I'd move those into bitcoin.messages but ... that's already being used and that has a completely different context, any idea where these should go?

• class BitcoinMessage(ImmutableSerializable)
• def SignMessage(key, message)
• def VerifyMessage(address, message, sig)

[rubensayshi]

I just moved them into bitcoin.sign_verify_message, just to already seperate them, but it should get a more sensible name, I just can't come up with anything good ...

[petertodd]

How about just bitcoin.signmessage?

It'd be good to have signmessage.py and verifymessage.py scripts in the examples/ directory showing the functionality off too.

[rubensayshi]

okay, bitcoin.signmessage sounds good, moved!
also added example signmessage.py that does both, not really neccesary to have 2 scripts.

and I rebased and squashed all the commits into 1

[rubensayshi]

@petertodd I think this is good to go?

[petertodd]

Thanks!

Sorry, was out of the country, as usual. :/

[rubensayshi]

awesome! thanks!

can we also get a v0.4.1 ;) ?

[petertodd]

Time for a v0.5.0 I think.