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I call it the privacy doom principle. Any information which separates you into a subset of a larger group can eventually be compounded to fully break your anony
by Taek 6y ago
I call it the privacy doom principle. Any information which separates you into a subset of a larger group can eventually be compounded to fully break your anonymity.
I did a lot of work on privacy coins, and the power of statistics is staggering. Doesn't matter if you shield yourself by grouping with 100,000 people per transaction, if your anonymity set isn't _everyone_, eventually you can be singly identified.
Same goes for browsers, tracking, and "anonymized data".
- prepend 6y agoEspecially if you can belong to multiple 100,000 people groups. It doesn’t take very many until you can find an individual by looking at the intersections.
- ComodoHacker 6y agoSo can privacy coins scale or all the efforts put there were futile?
- Taek 6y agoPrivacy coins can work if you can maintain the property that _every_ transaction could plausibly be spending _any_ historic output. For the most part, that's just Zcash-like coins
- matheusmoreira 6y agoWhat about Monero?
- Taek 6y agoMonero fails the privacy doom principle, eventually analytics will be enough to fully break it. In the long term, it's not really any safer than bitcoin.
- matheusmoreira 6y agoCan you elaborate? It's my understanding that Monero uses ring signatures and that it's impossible to tell which key actually signed the transaction. It's also impossible to correlate multiple transactions without external metadata such as exchange records. This implies there's no way to compute intersections of the set of keys in all related transactions until only one element remains.
- salawat 6y agoThink about it. What is the point of a transaction you can't eventually confirm whether it happened or not? Monero may utilize a heaping helping of obfuscatory steps, but those steps need to be consistent, and reversible. Otherwise, you have no guarantee that someone well placed hasn't modified the record in all the right places. Nation state's sole reason for existence is to implement solutions to these kinds of hard-to-reverse problems by sponsoring tooling and regulation to ensure that knowledge graph can be traversed. Either through mandatory reporting of the requisite metadata by exchanges that handle those transactions en-masse and who make money off it as a pre-condition of doing business, or by banning systems and instituting penalties for being discovered to use such an unreversible system. This is the part that blockchain people don't get. If you have a public ledger, it's a matter of time until LE and regulators figure out how to legally constrain you. You may have a chunk of time when you can get away with untraceable transactions, but measures will eventually be implemented that will practically break anonymity for a lawfully operated business if you keep any sort of bifurcated record. Then there's the final measure of making it impossible to legally reenter the fiat market from these types of assets as well. Successful money laundering is already fairly difficult. Without a way to feasibly re-enter, it becomes that much harder. While in theory you could have two monetary instruments that fuel disjoint economic systems, there still has to be a cross-over point, and you can bet that that will be the point of maximum scrutiny. Not saying it's impossible to make work, but don't expect everyone else to make it easy for you. The glacier may not move quickly, but it does in fact, move.
- ComodoHacker 6y agoDoesn't that defeat the purpose of blockchain?
- CodesInChaos 6y agoThe purpose of the blockchain is to prevent double spends. For bitcoin that's done by maintaining the set of unspent transaction outputs. AFAIR Zcash maintains the set of spent serial numbers instead, so it scales worse in that regard.
- ixwt 6y agoThere's an old post about the Anime Death Note and the "bits of entropy" in relation to anonimity. It boils down to enough true/false questions about a person is enough information to uniquely identify them.
- swsieber 6y agoI think this is the post: https://www.gwern.net/Death-Note-Anonymity https://www.gwern.net/Death-Note-Anonymity
- geofft 6y agoLooks like https://www.gwern.net/Death-Note-Anonymity https://www.gwern.net/Death-Note-Anonymity , which has a lot of references and side notes more relevant to this story than to Death Note per se, e.g., > The researchers generalized their Netflix work to find isomorphisms between arbitrary graphs (such as social networks stripped of any and all data except for the graph structure), for example Flickr and Twitter , and give many examples of public datasets that could be de-anonymized—such as your Amazon purchases (Calandrino et al 2011 ; blog).
- jrott 6y agoAlso works for health data as well[0] if anonymity is actually important it's really hard to collect data at all. [0] https://www.nature.com/articles/s41467-019-10933-3 https://www.nature.com/articles/s41467-019-10933-3
- rocqua 6y agoWhich privacy coins did you look at, and what kind of results did you get? Sounds quite interesting!
- bogomipz 6y agoDid you publish any work on your privacy coin findings? If not might you or someone else have some links to share regarding their strengths and weaknesses?
- noofen 6y agoI'm curious of your thoughts on Tornado Cash [1]. [1]: https://tornado.cash/ https://tornado.cash/
- bombcar 6y agoAn example everyone knows is “twenty questions” - applied to people it’s not hard to narrow you down to “you” having never asked a question that doesn’t roughly divide the population 50/50. Example: 1. male? 2. East of the Mississippi? Etc etc.
- Zacru 6y agoYour comment reminded me of this minutephysics video about the census. https://youtu.be/pT19VwBAqKA https://youtu.be/pT19VwBAqKA It a great walkthrough of the "privacy doom principle."
- deleted 6y ago[deleted]