bcwallet: A /dev/wallet for Bitcoin • Hacker News Board

Re: bcwallet: A /dev/wallet for Bitcoin

#11

Post by vessenes » Tue, Mar 22, 2016, 12:31 AM UTC

midas wrote: post #4

vessenes wrote: post #2

This is just a public service announcement: depending on implementation of a standard hierarchical wallet, leaking a list of public addresses and a _single_ private key can leak unlimited forward private keys, especially if the public addresses are sequentially generated ones. This was true for some implementations of BIP32, for instance. I don't know if blockcypher's wallet is vulnerable to this attack, but it's not…

Wallet author here, thanks @vessenes for the comment. Yes, as with all HD wallets, an attacker with a single private key and the the extended public key can derive all child private keys. You can read more about that aspect of HD wallets in this blog post here ( https://bitcoinmagazine.com/articles/deterministic-wallets-a... ). What's important to keep in mind, is that the child keys never leave your computer. In fac…

Thanks for the note back.

I think the attack vector that seems very likely here is an e-mail like this:

User: Initiates Support Request around a transaction that's funky

Naughty BlockCypher Employee: "Let's try to debug this. Can you get me a private key from an early address you sent from, one which you WON'T USE AGAIN? I want to check that we're doing our math correctly. Make sure it's not an address with an existing balance!"

I propose that well over 99% of developers would think "Will I use this address again? If not, should be fine to pass on this private key."

Re: bcwallet: A /dev/wallet for Bitcoin

#12

Post by cyphar » Tue, Mar 22, 2016, 7:39 AM UTC

ape4 wrote: post #9

ecma wrote: post #8

You realize that /dev/ is for devices, not developers, right? The title of the OP is fairly misleading because of that. Otherwise, an interesting project. I'd be interested to know why you chose Python and if/how you protect against code poisoning on the user's machine.

I was expecting echo give 5 bitcoin to mike > /dev/bitcoin head /dev/bitcoin shows recent translations

Someone should write that. It shouldn't be too bad (but it would be ugly, since you'd probably have to write either something in FUSE and do some horrible bindmount magic or create a kernel module that would then have to call out to userspace).

Re: bcwallet: A /dev/wallet for Bitcoin

#13

Post by gizi » Tue, Mar 22, 2016, 8:53 AM UTC

bcwallet is a cli with an interactive user interface. I never use a cli program that possibly could start waiting for user input. It could cause a "halting problem" in the script that incorporates it. That is literally a show stopper. Waiting for user input in a commandline script, is bug. It is not a feature. That bcwallet thing is simply full of bugs.

Browsers and things like that are valid interactive user interfaces. The cli/shell mostly exists to test stuff so that you can add it to a script, which you can add again to another script, ad nauseam ;-)

The actually interesting part in all of this has been done by bitmerchant.

Unfortunately, bitmerchant has no simple cli program attached. You need to deal with python instead, even if you have nothing to do with python. That is also a show stopper. Please, also learn haskell, ocaml, perl, lua, and two other undecisive motherfuckers, just because you want to incorporate one or two cli actions written in another scripting vernacular, into your own script.

I don't want to know in what it was written. If I cannot ignore in what it was written, I will probably avoid using it.

So, we almost had a functioning solution.

Of course, a simple man page would have been phanthastick. But ok, we are not going to incessantly demand that people work for free! ;-)