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Discussion : Christian & Florian, This is about the UI paper in SPACE, not the protocol paper with real crypto discussions. And the text in question never existed in the protocol paper. Ian, I'm the member of our team who looked into BOLT the most, mostly looking to see if any of the ideas helped us. I might manage to reconstruct more details later, but right now my description there sounds bizarre and wrong. In Taler, our denomination key expirations limit the exchange's liability to double its deposits, even in the case that its private keys are all compromised and used to create unbacked coins. In practice, offline ecash schemes lack this limit due to their decreased ability to rotate denomination keys. I do not see why I wrote that BOLT lacked this property: If I recall, both BOLT payment channel types are created with fixed initial value commitments. In particular, intermediaries have already committed the maximum funds they could transfer to each merchant. That would prevent unbacked transfers in the payment channel, and thus limit liability, even when the intermediary gets compromised. There is an anonymity cost if BOLT's approach limits the number of users in payment channels with each intermediary of course. I do not know if a compromised BOLT intermediary could complete payments to merchants while refunding customers, but even if so that's still not the sort of "unlimited" liability you get in offline ecash schemes. It's just the sort of 2x limit on liability that Taler provides. In BOLT, the x would be value committed to outgoing channels, while in Taler x is value deposited by customers, so I suppose the intermediary could technically be robbed of their money without seeing any incoming money. That's not "unlimited" though. It's limited by the intermediary's commitments to the network. I doubt I even thought about it this deeply though when I wrote that. I think once-upon-a-time I wanted to express some vague concern around intermediaries and anonymity sets in BOLT, but never thought about it clearly, and later managed to confuse myself with conventional ecash issues when discussing related work with Christian while we were writing this usability paper. Sorry for writing what appears to be nonsense! Jeff On Mon, 2017-08-28 at 21:10 +0200, Christian Grothoff wrote: > > -------- Forwarded Message -------- > Subject: bolt attack? > Date: Mon, 28 Aug 2017 18:49:43 +0000 > From: Ian Miers <imiers@cs.jhu.edu> > To: christian@grothoff.org <christian@grothoff.org> > > > > Hi, > Someone pointed me at a copy of your Taler paper from 2016 and pointed > out that it describes Bolt saying there "are numerous seemingly > fragile aspects of the BOLT protocol, including aborts deanonymizing > customers, *intermediaries risking unlimited losses,* and theft if a > party fails to post a refute message in a timely fashion." > > The unlimited loss to intermediaries comment surprised both them and > me. Are you referring to some specific attack or an issue involving > timeouts and delays? > > Thanks, > Ian |
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GNU Taler WebExtension Wallet ============================= Cross-browser GNU Taler wallet written for the WebExtensions API. Installation ============ Run `./configure && make' to create an archive containing the extension in ./build/taler-wallet-$VERSION.zip Dependencies ============ See thirdparty/README for a list of dependencies that are checked into this repository as a git subtree. This project also has the following third-party runtime dependencies, which are checked in compiled or minified form: - React (Facebook Inc., BSD License) Emscripten compiled dependencies: * libgnunetutil * libgnunetjson * libgcrypt * libunistring Documentation ============= See the documentation at http://doc.taler.net/dev-wallet-wx.html