Re: [Bitcoin-development] Proposal to address Bitcoin malware

[devrandom <c1.sf-bitcoin@niftybox.net>]

There are a couple of attack vectors to consider:

* The recipient's machine is compromised
* The sender's machine is compromised

BIP-70 and other ways of having the sender verify the destination on a
second device will help protect against sender compromise.  For a
person-to-person situation, you could verify the address by voice.

For the case where the recipient is compromised, you would want to
verify the address with the recipient's multisig security service.
Extending BIP-70 to allow multiple signatures would be one way to go
about this.  You would at least want to have a web page controlled by
the security service where you can verify addresses.

On 2015-02-02 01:09 PM, Pedro Worcel wrote:
> Where would you verify that?
> 
> On 2/3/2015 10:03 AM, Brian Erdelyi wrote:
>> Joel,
>>
>> The mobile device should show you the details of the transaction (i.e.
>> amount and bitcoin address).  Once you verify this is the intended
>> recipient and amount you approve it on the mobile device.  If the
>> address was replaced, you should see this on the mobile device as it
>> won’t match where you were intending to send it.  You can then not
>> provide the second signature.
>>
>> Brian Erdelyi
>>
>>> On Feb 2, 2015, at 4:57 PM, Joel Joonatan Kaartinen
>>> <joel.kaartinen@gmail.com <mailto:joel.kaartinen@gmail.com>> wrote:
>>>
>>> If the attacker has your desktop computer but not the mobile that's
>>> acting as an independent second factor, how are you then supposed to
>>> be able to tell you're not signing the correct transaction on the
>>> mobile? If the address was replaced with the attacker's address,
>>> it'll look like everything is ok.
>>>
>>> - Joel
>>>
>>> On Mon, Feb 2, 2015 at 9:58 PM, Brian Erdelyi
>>> <brian.erdelyi@gmail.com <mailto:brian.erdelyi@gmail.com>> wrote:
>>>
>>>
>>>     > Confusing or not, the reliance on multiple signatures as
>>>     offering greater security than single relies on the independence
>>>     of multiple secrets. If the secrets cannot be shown to retain
>>>     independence in the envisioned threat scenario (e.g. a user's
>>>     compromised operating system) then the benefit reduces to making
>>>     the exploit more difficult to write, which, once written, reduces
>>>     to no benefit. Yet the user still suffers the reduced utility
>>>     arising from greater complexity, while being led to believe in a
>>>     false promise.
>>>
>>>     Just trying to make sure I understand what you’re saying.  Are
>>>     you eluding to that if two of the three private keys get
>>>     compromised there is no gain in security?  Although the
>>>     likelihood of this occurring is lower, it is possible.
>>>
>>>     As more malware targets bitcoins I think the utility is evident. 
>>>     Given how final Bitcoin transactions are, I think it’s worth
>>>     trying to find methods to help verify those transactions (if a
>>>     user deems it to be high-risk enough) before the transaction is
>>>     completed.  The balance is trying to devise something that users
>>>     do not find too burdensome.
>>>
>>>     Brian Erdelyi
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>>
>>
>>
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> 
> 
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-- 
devrandom / Miron