Multisig Vault • Hacker News Board

Re: Multisig Vault

#31

Post by IkmoIkmo » Thu, Oct 30, 2014, 12:04 AM UTC

vijayboyapati wrote: post #28

The most powerful part of multi-sig is not that you can have arbitrarily many M of N, but that you can outsource complex policy in a trusted way. E.g., create policy that lower level employees can control a small percentage of a company's holdings, while higher level employees can control a higher percent. It allows you to implement flexibility that exists in the credit system, without giving up the trust/control tha…

Yeah it's pretty cool. At some point we'll see more enterprise software to take on some of the responsibilities to manage bitcoin funds like that. I think one or two such companies have already been VC funded.

The idea is that you can say create a fund with say 3 keys. One is given to the middle-manager, one is given to a senior manager, and one is given to a computer. The middle manager can go on and use up to 80% of the budget. He simply creates a transaction, signs it with his key, then sends it off. The computer sees it, and then does various fraud-type checks. It checks if the receiving address is a whitelisted partner address (e.g. a supplier) and if the amount falls within reason given payment history for example, and if the transaction doesn't use up more than 80% of the budget. It then co-signs it and the bitcoin is released.

For anything more, the computer simply won't sign it according to its programming. So the middle manager must go to the senior one to request permission to release earmarked funds.

It's just a simple example but you could move lots of the finance to a completely digital system, do immediate software-based accounting and program governance rules into the software, and spit out periodic transparency reports. Will be interesting to see when something like this gets integrated into existing ERP packages someday.

Re: Multisig Vault

#32

Post by imaginenore » Thu, Oct 30, 2014, 12:07 AM UTC

sillysaurus3 wrote: post #25

firepacket wrote: post #22

Earlier quoted context omitted.

Assuming your are using SSL, what exactly is the attack vector for getting a "foothold into your javascript execution" besides hacking Coinbase itself? Also, any attacker who gains a foothold of your operating system execution environment can trivially subvert your security as well. Does that mean crypto is broken on PCs?

any attacker who gains a foothold of your operating system execution environment can trivially subvert your security as well. Does that mean crypto is broken on PCs? Yes, of course your crypto is broken if an attacker has malware running on your device. The difference between that scenario and Coinbase is that your device only affects you. A break in Coinbase's security will affect hundreds of thousands of people. As…

> First, XSS. If Coinbase ever has an XSS vuln which allows JS to execute in the same context as their crypto key generation, then that attacker can silently siphon keys as they're being generated

So a very very very specific XSS vulnerability that affects the key generation process. I'm pretty sure that can be solved by not allowing any user input during the generation.

> Second attack vector: Third-party JS libraries. If Coinbase is loading JS from any external source

So don't load any external JS libraries on the key-generating pages.

> The third attack vector, which a sibling comment mentioned, is a rogue browser extension.

That's ridiculous. If you download malware on any OS, and allow it to run, it can do whatever within whatever permissions you allowed. Malware has been stealing money and identities long before Bitcoin was invented. Users need to learn not to install crap.

That can also be solved at the browser level - a website should be able to request a secure extension-less mode.

Re: Multisig Vault

#33

Post by sillysaurus3 » Thu, Oct 30, 2014, 1:43 AM UTC

BillinghamJ wrote: post #30

sillysaurus3 wrote: post #25

Earlier quoted context omitted.

any attacker who gains a foothold of your operating system execution environment can trivially subvert your security as well. Does that mean crypto is broken on PCs? Yes, of course your crypto is broken if an attacker has malware running on your device. The difference between that scenario and Coinbase is that your device only affects you. A break in Coinbase's security will affect hundreds of thousands of people. As…

Coinbase is insured, so in theory yes.

Really? Insured by who, and to pay out under what circumstances? What if every coin disappeared tomorrow?

Re: Multisig Vault

#34

Post by sillysaurus3 » Thu, Oct 30, 2014, 1:55 AM UTC

imaginenore wrote: post #32

sillysaurus3 wrote: post #25

Earlier quoted context omitted.

any attacker who gains a foothold of your operating system execution environment can trivially subvert your security as well. Does that mean crypto is broken on PCs? Yes, of course your crypto is broken if an attacker has malware running on your device. The difference between that scenario and Coinbase is that your device only affects you. A break in Coinbase's security will affect hundreds of thousands of people. As…

> First, XSS. If Coinbase ever has an XSS vuln which allows JS to execute in the same context as their crypto key generation, then that attacker can silently siphon keys as they're being generated So a very very very specific XSS vulnerability that affects the key generation process. I'm pretty sure that can be solved by not allowing any user input during the generation. > Second attack vector: Third-party JS librari…

A hypothetical extension-less mode isn't a bad idea. Unfortunately, it doesn't exist.

An XSS attack in an unrelated part of the webpage can escalate. If someone hijacks the session key of an admin, they get access to the admin panel. That access may or may not let them further escalate their privileges. If they manage to break into the box that serves the JS for the key generation page, then they can alter the JS however they want, including so subtly that no one will notice it's broken. Think this is unlikely? Privilege escalation attacks like this happen all the time. Again, the potential payout for a successful heist is in the range of millions, and due to bitcoin mixers, they're less likely to be caught.

Also, I bet at least one person reading this has the "Cloud To Butt" extension installed. It's not only untrained users who install that sort of thing.

Re: Multisig Vault

#35

Post by andrewljohnson » Thu, Oct 30, 2014, 4:22 AM UTC

IkmoIkmo wrote: post #31

vijayboyapati wrote: post #28

The most powerful part of multi-sig is not that you can have arbitrarily many M of N, but that you can outsource complex policy in a trusted way. E.g., create policy that lower level employees can control a small percentage of a company's holdings, while higher level employees can control a higher percent. It allows you to implement flexibility that exists in the credit system, without giving up the trust/control tha…

Yeah it's pretty cool. At some point we'll see more enterprise software to take on some of the responsibilities to manage bitcoin funds like that. I think one or two such companies have already been VC funded. The idea is that you can say create a fund with say 3 keys. One is given to the middle-manager, one is given to a senior manager, and one is given to a computer. The middle manager can go on and use up to 80% o…

I don't get why you need BitCoin/multisig for this. As long as you are "giving a key" to a computer, this is no different than programming a computer to oversee the middle-manager's spending from a bank account.

I get that multi-sig and bitcoin can be good, but as long as you already have the decision-making and power setup of a corporation, this is a marginal benefit. I would see this technology being more useful for trust-type situations where you might want to give a lawyer, a beneficiary, and a guardian a key. Or any sort of situation where power is actually split between multiple entities - seems like the boss still has all the power in the situation described.

Re: Multisig Vault

#36

Post by yason » Thu, Oct 30, 2014, 7:21 AM UTC

I wouldn't trust any third party to keep my bitcoins except for the money in transit. I have my local client and local wallet, and that's where I do my transactions from.

Re: Multisig Vault

#37

Post by spacefight » Thu, Oct 30, 2014, 8:01 AM UTC

imaginenore wrote: post #32

sillysaurus3 wrote: post #25

Earlier quoted context omitted.

any attacker who gains a foothold of your operating system execution environment can trivially subvert your security as well. Does that mean crypto is broken on PCs? Yes, of course your crypto is broken if an attacker has malware running on your device. The difference between that scenario and Coinbase is that your device only affects you. A break in Coinbase's security will affect hundreds of thousands of people. As…

> First, XSS. If Coinbase ever has an XSS vuln which allows JS to execute in the same context as their crypto key generation, then that attacker can silently siphon keys as they're being generated So a very very very specific XSS vulnerability that affects the key generation process. I'm pretty sure that can be solved by not allowing any user input during the generation. > Second attack vector: Third-party JS librari…

> So don't load any external JS libraries on the key-generating pages.

And anywhere else. The local banks in my country are not doing this. And a wallet site shouldn't ether. Even the coinbase login screen pings olark.com all the time.

Oh, and if you look at their CSP report sending back home, the original-policy is quite scary.

Re: Multisig Vault

#38

Post by wcoenen » Thu, Oct 30, 2014, 8:12 AM UTC

icebraining wrote: post #26

adrianmacneil wrote: post #18

Earlier quoted context omitted.

If the computer is infected, then yes it would be possible to steal both the private keys, and the passphrase. To avoid this attack scenario, we're investing pretty heavily in technologies such as CSP. However, this can be mitigated with our group multisig vault, where separate users create their own keys. For malware to steal these, it would require infecting multiple computers.

Seems like the next step would be to allow the users to store their copies on a smart card instead of a PC.

Like the Trezor[1] hardware wallet.

[1] http://www.bitcointrezor.com

Re: Multisig Vault

#39

Post by icebraining » Thu, Oct 30, 2014, 8:26 AM UTC

wcoenen wrote: post #38

icebraining wrote: post #26

Earlier quoted context omitted.

Seems like the next step would be to allow the users to store their copies on a smart card instead of a PC.

Like the Trezor[1] hardware wallet. [1] http://www.bitcointrezor.com

Yes, but maintaining the encrypted copy on Coinbase's servers, to ensure that losing the card doesn't mean losing the wallet.

Re: Multisig Vault

#40

Post by exo762 » Thu, Oct 30, 2014, 8:36 AM UTC

yason wrote: post #36

I wouldn't trust any third party to keep my bitcoins except for the money in transit. I have my local client and local wallet, and that's where I do my transactions from.

The whole point in multi-signature scheme is to remove need to trust Coinbase.

Your local client and local wallet are fine, until your keys are stolen by malware. Multisig scheme also attempts to fix that flaw.

EDIT: multisig scheme with user's key on Trezor. This way you are also protected fully from viruses stealing your local key.