Author: devrandom 2015-02-02 21:30:03
Published on: 2015-02-02T21:30:03+00:00
Two potential attack vectors for Bitcoin transactions are the compromise of either the recipient's or sender's device. To protect against sender compromise, BIP-70 and other methods can be used to have the sender verify the destination on a second device, while in person situations could involve verifying the address by voice. In the case of recipient compromise, the address can be verified with the recipient's multisig security service, with one way to accomplish this being to extend BIP-70 to allow multiple signatures. At minimum, a web page controlled by the security service should exist where addresses can be verified. To illustrate how this works, an example was given where if an attacker has access to a desktop computer but not the mobile device that is acting as an independent second factor, it becomes difficult to tell if the correct transaction is being signed on the mobile device. The mobile device should show details of the transaction, such as the amount and Bitcoin address, so that users can verify that they match what was intended. If the address was replaced, the user would see this on the mobile device and could choose not to provide the second signature. While there is a balance between devising something that users do not find too burdensome and ensuring greater security, more malware targeting Bitcoins makes the utility of finding methods to verify transactions evident. It is important to note that the reliance on multiple signatures offering greater security than single relies on the independence of multiple secrets. If two out of three private keys are compromised, then there is no gain in security, although the likelihood of this occurring is lower but possible. Finally, it is worth noting that Bitcoin transactions are final, making it even more critical to verify them before they are completed.
Updated on: 2023-06-09T16:09:01.401408+00:00