

Launching Co-Sign Pages and M-of-15 Multisig API - nvk
http://blog.coinkite.com/post/102291566521

======
btcde
Is your multisig compatible with other multisig solutions (Copay, Armory ...)?
If yes, to what degree? Are there any standards for multisig?

~~~
nvk
We are using P2SH and multisig transactions the same as everyone else, and we
tried to interop with others, but it's not easy. They problems are discussed
[in the
FAQ]([https://coinkite.com/faq/multisig](https://coinkite.com/faq/multisig)).
Key generation is open and interop with brainwallet and bip32.org

We've added this to help you with that.
[http://cl.ly/image/0g2d3x1T3o0H/Detail%20View%3A%20Account%2...](http://cl.ly/image/0g2d3x1T3o0H/Detail%20View%3A%20Account%20'test-
prod'%202014-11-18%2010-30-41.png)

    
    
        Do Coinkite shared accounts interoperate with other vendors?
        
        Although we are using the latest Bitcoin standards and technologies, it is hard to interoperate because of the following issues:
        
            - Both parties need to correctly track all future and past P2SH addresses.
            - Other "multisig" vendors are using P2SH and multisig in very limited ways.
            - Most other vendors are keeping one private key to themselves, which prevents any useful interop.
            - The BIP32 HD wallet paths are not well standardized.
            - Any mistake or incompatibility can lead to lost funds and very bad karma.
            
        However, to encourage progress in this area, we do include a "data export" option for one US-based exchange (Coinbase) and will add support for other vendors if it is useful. We also provide a one-click data export of all the details of the shared account, in our own simple JSON format.
        
        We cannot provide technical support for individual end-users attempting to interoperate, but we are willing to speak to other vendors and support the greater crypto-currency community.
    

*edit: layout

~~~
btcde
Thanks, how can I send bitcoins out if Coinkite shuts down? Let's say I made
copies of all MofN pribkeys.

~~~
nvk
Assuming you have the xprvkey for M of your N keys, then you just need to find
the UTXO for your funds and publish a transaction that moves that to another
key.

We list all UTXO for your account (with all the transaction hashes needed) in
what we call the "audit report" and that includes multisig accounts now too.
The subkey needed (M/x) is indicated in that report as well. Armed with that
information, a site like ms-brainwallet can produce and send the transaction
you need.

Also for you doomsday planning: we email a copy of the HSM private keys
associated with your multisig account, encrypted with Coinkite master key that
would be published after we shutdown. (Very similar to what we've always done
with regular accounts).

------
btcde
This is amazing, specially because I can upload my own keys.

~~~
mirmir
I have in the past been a vocal critic if Coinkite, but now I take it back.

This is a very intelligent move and this does offer the security that is in
line with Bitcoin principles - actions speak louder than words and in this
case they have listened to criticism and acted correctly.

~~~
petertodd
I've always told people in the past the Coinkite's model - trust Coinkite to
handle security for you - has a valuable place in the Bitcoin ecosystem,
however it's certainly not for everyone. I personally use Coinkite to store a
portion amount of my Bitcoin savings as a diversity measure, but I'd never
trust them with everything.

But this new multisig support gives you the option to have the best of both
worlds: Coinkite helps keep your Bitcoin's safe, and so do you. And I'll
probably move the Bitcoins I currently store at Coinkite to a Coinkite
multisig account myself.

Disclaimer: I'm Coinkite's Chief Naysayer.
[http://blog.coinkite.com/post/85842528071/peter-todd-
joins-c...](http://blog.coinkite.com/post/85842528071/peter-todd-joins-
coinkite-as-chief-naysayer)

