October 2005 - cypherpunks-legacy

[PracticalSecurity] Anonymity - great technology but hardly used
by R.A. Hettinga 24 Oct '05

24 Oct '05

--- begin forwarded text Date: Mon, 24 Oct 2005 23:31:34 +0200 To: practicalsecurity(a)hbarel.com From: Hagai Bar-El <info(a)hbarel.com> Subject: [PracticalSecurity] Anonymity - great technology but hardly used Sender: PracticalSecurity-bounces(a)hbarel.com Hello, I wrote a short essay about anonymity and pseudonymity being technologies that are well advanced but seldom used. Following are excerpts from the essay that can be found at: http://www.hbarel.com/Blog/entry0006.html In spite of our having the ability to establish anonymous surfing, have untraceable digital cash tokens, and carry out anonymous payments, we don't really use these abilities, at large. If you are not in the security business you are not even likely to be aware of these technical abilities. If I may take a shot at guessing the reason for the gap between what we know how to do and what we do, I would say it's due to the overall lack of interest of the stakeholders. Fact probably is, most people don't care that much about anonymity, and most of the ones who do, are not security geeks who appreciate the technology and thus trust it. So, we use what does not require mass adoption and do not use what does. Anonymous browsing is easy, because it does not need an expensive infrastructure that requires a viable business model behind it; fortunately. A few anonymity supporters run TOR servers on their already-existent machines, anonymity-aware users run TOR clients and proxy their browsers through them, and the anonymity need is met. The onion routing technology that TOR is based on is used; not too often, but is used. The problem starts with systems that require a complex infrastructure to run, such as anonymous payment systems. As much as some of us don't like to admit it, most consumers do not care about the credit card company compiling a profile of their money spending habits. Furthermore, of the ones who do, most are not security engineers and thus have no reason to trust anonymity schemes they don't see or feel intuitively (as one feels when paying with cash). The anonymous payment systems are left to be used primarily by the security-savvy guys who care; they do not form a mass market. I believe that for anonymity and pseudonymity technologies to survive they have to be applied to applications that require them by design, rather than to mass-market applications that can also do (cheaper) without. If anonymity mechanisms are deployed just to fulfill the wish of particular users then it may fail, because most users don't have that wish strong enough to pay for fulfilling it. An example for such an application (that requires anonymity by design) could be E-Voting, which, unfortunately, suffers from other difficulties. I am sure there are others, though. Regards, Hagai. _______________________________________________ PracticalSecurity mailing list PracticalSecurity(a)hbarel.com http://hbarel.com/mailman/listinfo/practicalsecurity_hbarel.com --- end forwarded text -- ----------------- R. A. Hettinga <mailto: rah(a)ibuc.com> The Internet Bearer Underwriting Corporation <http://www.ibuc.com/> 44 Farquhar Street, Boston, MA 02131 USA "... however it may deserve respect for its usefulness and antiquity, [predicting the end of the world] has not been found agreeable to experience." -- Edward Gibbon, 'Decline and Fall of the Roman Empire'

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Re: [fc-discuss] Financial Cryptography Update: On Digital Cash-like Payment Systems
by cyphrpunk 24 Oct '05

24 Oct '05

Let's take a look at Daniel Nagy's list of desirable features for an ecash system and see how simple, on-line Chaum ecash fares. > http://www.epointsystem.org/~nagydani/ICETE2005.pdf > > One of the reasons, in the author s opinion, is that payment systems > based on similar schemes lack some key characteristics of paper-based > cash, rendering them economically infeasible. Let us quickly enumerate > the most important properties of cash: > > 1. "Money doesn't smell." Cash payments are -- potentially -- > _anonymous_ and untraceable by third parties (including the issuer). This is of course the main selling point of Chaum's system, where it excels. I will point out that defining cash as merely "potentially" anonymous leaves a loophole whereby fully non-anonymous systems get to call themselves cash. This underplays the strength of Chaum's system. It is not just "potentially" anonymous, it has a strong degree of anonymity. > 2. Cash payments are final. After the fact, the paying party has no > means to reverse the payment. We call this property of cash > transactions _irreversibility_. Certainly Chaum ecash has this property. Because deposits are unlinkable to withdrawals, there is no way even in principle to reverse a transaction. > 3. Cash payments are _peer-to-peer_. There is no distinction between > merchants and customers; anyone can pay anyone. In particular, anybody > can receive cash payments without contracts with third parties. Again this is precisely how Chaum ecash works. Everyone can receive ecash and everyone can spend it. There is no distinction between buyers and vendors. Of course, transactions do need the aid of the issuer, but that is true of all online payment systems including Daniel's. > 4. Cash allows for "acts of faith" or _naive transactions_. Those who > are not familiar with all the antiforgery measures of a particular > banknote or do not have the necessary equipment to verify them, can > still transact with cash relying on the fact that what they do not > verify is nonetheless verifiable in principle. I have to admit, I don't understand this point, so I can't say to what extent Chaum ecash meets it. In most cases users will simply use their software to perform transactions and no familiarity is necessary with any antiforgery or other technical measures in the payment system. In this sense all users are "naive" and no one is expected to be a technical expert. Chaum ecash works just fine in this model. > 5. The amount of cash issued by the issuing authority is public > information that can be verified through an auditing process. This is the one aspect where Chaum ecash fails. It is a significant strength of Daniel Nagy's system that it allows public audits of the amount of cash outstanding. However note that if the ecash issuer stands ready to buy and sell ecash for "real money" then he has an incentive not to excessively inflate his currency as it would create liabilities which exceed his assets. Similarly, in a state of competition between multiple such ecash issuers, any currency which over-inflates will be at a disadvantage relative to others, as discussed in Dan Selgin's works on "free banking". Daniel Nagy also raised a related point about insider malfeasance, which is also a potential problem with Chaum ecash, but there do exist technologies such as hardware security modules which can protect keys in a highly secure manner and make sure they are used only via authorized protocols. Again, the operators of the ecash system have strong incentives to protect their keys against insider attacks. > The payment system proposed in (D. Chaum, 1988) focuses on the first > characteristic while partially or totally lacking all the others. In summary, I don't think this is true at all. At least the first three characteristics are met perfectly by Chaumian ecash, and possibly the fourth is met in practice as naive users can access the system without excessive complications. Only the fifth point, the ability for outsiders to monitor the amount of cash in circulation, is not satisfied. But even then, the ecash mint software, and procedures and controls followed by the issuer, could be designed to allow third party audits similarly to how paper money cash issuers might be audited today. There do exist technical proposals for ecash systems such as that from Sander and Ta-Shma which allow monitoring the amount of cash which has been issued and redeemed while retaining anonymity and unlinkability, but those are of questionable efficiency with current technology. Perhaps improved versions of such protocols could provide a payment system which would satisfy all of Daniel Nagy's desiderata while retaining the important feature of strong anonymity. CP

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24 Oct '05

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[djm@mindrot.org: Re: [smb@cs.columbia.edu: Skype security evaluation]]
by Eugen Leitl 24 Oct '05

24 Oct '05

----- Forwarded message from Damien Miller <djm(a)mindrot.org> -----

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[goodell@eecs.harvard.edu: Re: Access for the uncomputed]
by Eugen Leitl 24 Oct '05

24 Oct '05

----- Forwarded message from Geoffrey Goodell <goodell(a)eecs.harvard.edu> -----

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[arma@mit.edu: Re: Publicizing Hidden Services]
by Eugen Leitl 24 Oct '05

24 Oct '05

----- Forwarded message from Roger Dingledine <arma(a)mit.edu> -----

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by Melinda Shelton 23 Oct '05

23 Oct '05

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[dave@farber.net: [IP] more on Colleges protest netwoprk upgrades to allow easier surveillance]
by Eugen Leitl 22 Oct '05

22 Oct '05

----- Forwarded message from David Farber <dave(a)farber.net> -----

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[dave@farber.net: [IP] CALEA and Colleges]
by Eugen Leitl 22 Oct '05

22 Oct '05

----- Forwarded message from David Farber <dave(a)farber.net> -----

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Re: Judy Miller needing killing
by John Kelsey 22 Oct '05

22 Oct '05

>The question is, can >she defy a subpoena based on membership in the privileged Reporter class >that an "ordinary" person could not defy? It seems like the real question is how membership in the class is determined. If anyone who's acting like a reporter in a certain context (say, Adam Shostack interviewing me for his blog) qualifies, then I don't see the constitutional problem, though it may still be good or bad policy. If you've got to get a special card from the government that says you're a journalist, it seems like that's more of a problem. I guess other places where there's some right not to answer these questions exist, but they're mostly based on licensed professions. I gather your lawyer or priest has much more ability to refuse to talk than your doctor or accountant, and that your psychologist has a shockingly small ability to refuse to talk. Other than priest, though, all these fields are at least somewhat licensed by the state for other reasons, so that makes it easy to use possession of a license as a way to tell when someone really is a doctor, lawyer, psychologist, etc. For constitutional reasons, that's not really true for journalists. >GH --John

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