Author: Mike Hearn 2014-11-08 16:04:48
Published on: 2014-11-08T16:04:48+00:00
There have been significant developments in the space of decentralized 2-factor Bitcoin wallets. The wallets run on desktops and laptops, and are paired with a mobile app (currently only available for Android). Alon Muroch and Chris Pacia have made considerable progress on their HD wallet app, Bitcoin Authenticator. The desktop wallet triggers a push notification to the mobile app when sending money, which presents the transaction for confirmation. It is currently in alpha, but expected to be popular due to its focus on UI and simple mobile security model.Bitcoin Authenticator uses P2SH/CHECKMULTISIG for the 2-factor functionality, which has downsides such as less support for address types and larger transactions that waste blockchain space and result in higher fees. To solve this problem, Christopher Mann and Daniel Loebenberger from Uni Bonn have ported the efficient DSA 2-of-2 signing protocol by MacKenzie and Reiter to ECDSA, and implemented their own desktop/Android wallet app pair showing that it works and has good enough performance. This means that P2SH/CHECKMULTISIG is no longer required for the two-factor auth case, and thus it's as cheap as using regular addresses.Their protocol uses a combination of ECDSA, Paillier homomorphic encryption, and some zero knowledge proofs to build a working solution for the 2-of-2 case only. Their code is liberally licensed and looks easy to integrate with Alon and Chris' more user-focused work. Currently, neither of these projects implement support for BIP70, so the screen you see when signing the transaction is hardly user-friendly or secure without trusting the destination address. Support for sending a full payment request between devices is the clear next step once these wallets have obtained a reasonable user base and are stable.
Updated on: 2023-06-09T14:11:36.780123+00:00