Re: Detectable cash notes a fantasy
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Tim wrote: Faustine wrote: If, when I came here, I had made the deliberate choice to make an effort at getting along by emphasizing our similarities instead of differences, I dare say the motivation to dissect-and-destroy every last comment I ever make would be nonexistent. You haven't contributed anything interesting that I can recall. Oh of course not, heaven forfend. Even if you discount my comments, surely you must have noticed that rarely do your posts generate significant follow-up. (Which is a small blessing.) Who said generating a lot of follow-up was on my to-do list? Believe it or not, I'm perfectly fine with contributing here and there when I can and learning from everyone else when I can't. If I were as wrapped up in the pecking order dynamic as you seem to be, I'd really be putting a lot more effort into it. But as it is--given how incredibly busy I am--if my peculiar little set of toys is all I feel like bringing to share at sandbox right now, what concern is it of yours or anyone else's? Why not run along now and kick some sand on one of your boring asskisser friends, shake things up a little... Sometimes you natter about about (what) you think the RAND Corporation, your apparent ideal, would do things, Well is that a fact Grampy. Nattering about what interests me, alert the media. and sometimes you praise Herman Kahn Damn straight I do! Anyone interested in libertarian futurism really ought to check him out if they haven't already--and I'm assuming this description applies to quite a few people here...good starting links: http://www.alteich.com/links/kahn.htm I seem to remember your having a few kind words for a work or two of his yourself--so I do hope you won't go running down a great man just for the sake of getting at me. and other O.R. types. Hooey. But you have nothing significant to contribute about anything closely related to list themes. There you go again, defining what's acceptable for people what to talk about. Anyway, as always, it's not what you say or don't say on a list, its what you do. In the abstract, it would be kind of useful to talk to you about it, but in practice that's not really an option. A shame, really. You should think about some of the real issues and come up with some kind of incisive analysis or creative proposal As should we all. Fair enough, but I've written plenty I haven't felt like posting here for a number of reasons. Maybe I will, maybe not, who cares. Even if I left it to others to post significant ideas it hardly matters. even Choate is more on-topic than you've been. You know, I like arguing with Choate: too bad you pissed him off to the point he feels the need to post newslinks all the time. Did you catch how he didn't start up again until you said you quieted him down or whatever it was? Thanks a lot. The lectures from you about how we're a bunch of untrained amateurs are getting old. Oh come on, that's all in your head. Like you're one to talk about being condescending about what people know and dont know! Pot, kettle, look in the mirror. Looking forward to your next significant post, ~~Faustine. *** If you don't like 'em, ignore them or filter them. That's the Cypherpunk way of doing things. Tim May, on the Cypherpunks list, 1995 -BEGIN PGP SIGNATURE- Version: PGPsdk version 1.7.1 (C) 1997-1999 Network Associates, Inc. and its affiliated companies. (Diffie-Helman/DSS-only version) iQA/AwUBPLUJAfg5Tuca7bfvEQLdegCg+S2sDHGzsGOTBVPNMf9x8Bn3NWQAoOpF KG4JNBT8BOO+tK0+wjp6qVwn =tFxE -END PGP SIGNATURE-
RE: Detectable cash notes a fantasy
Eugen Leitl[SMTP:[EMAIL PROTECTED]] On Wed, 10 Apr 2002, Tim May wrote: How come? Because I am assuming the transponders are in the same position on each bill. If you want to posit some spatial diversity model, that helps, but not but a huge amount. This sounds too science fictionish to actually deploy (transponders are not the same as letters, and cannot be moved around on a random basis). The RFIDs are small enough to be able to positioned randomly within the fabric of the bill, but it still doesn't help if they yell in unison (something much less problematic with ultrawideband, admittedly). Phased array is sure nice, but homing in on a cloud of weak emitters with cm spatial jitter doesn't sound viable. Doorway antennas should be able to pickup a RFID-tagged cash signature relatively easily, though, though it won't be able to pick up the ID of each individual bill in a stack, unless you're willing to stand in that (shielded) doorway for a long time. [...] [1. Agreed, this thread has lost steam. 2. It always amazes me how often people on this list will handwave and speculate on subjects which a few minutes with Google will settle. Too often, we're like the medieval academics who debated endlessly over how many teeth a horse had, while refusing to go down to the stable to conduct an actual count. ] I refer you to the TI RFID FAQ, at http://www.ti.com/tiris/docs/customerService/faq.htm to quote:- 4) What is the minimum separation between Tags? There is no minimum separation between tags. Using the SID (anti-collision algorithm), multiple tags close to the antenna can be readily identified but if they are at the extreme reading range, they will require some separation (5 cm) to prevent mutual de-tuning. If individual tags are passing an antenna, some separation will need to be maintained if the anti-collision algorithm is not being used. The separation is related to the size of the reading zone and should be sufficient that only one tag is in the field at one time. 5) How many Tags can be identified? Using anti-collision techniques, there is theoretically no limit to the number of tags that could be inventoried at one time. Although, in the real world this is dependant on a number of factors: 1. The size of the reader's antenna 2. RF Power 3. How closely packed the tags are 4. How long you are prepared to wait for the data It requires a strong RF field for simultaneous identification, as tightly packed tags can 'soak up' the power and possibly de-tune each other if they are too close together. Smaller antennas have stronger RF fields close to the antenna, whereas a larger antenna, capable of reading more tags, and may have a less dense RF field. Using simultaneous identification, around 30 tags/ sec can be inventoried. If you wish to read extra data, the time required will increase, e.g. to inventory 20 tags and return one page of information from each, takes 1 second. Without simultaneous ID, up to 60 individual tags can be read in one second. -end of quote --- Righto. By the time EU will be tagging banknotes (and only bigger ones) I'm very ready to crush and/or nuke the RFID tags in the microwave. ... and run into trouble from salesdroids who won't accept them. [...] Peter Trei
RE: Detectable cash notes a fantasy
Eugen Leitl[SMTP:[EMAIL PROTECTED]] wrote: Remember that original issue was reading the embedded RFID in a stack of bills from across the room with a portable reader. A possibly shielded stack of bills. The FAQ you cited says 60 RFID tags/s reader speed under optimal consitions (I presume a bunch of naked RFID tags within cm of the reader) is impressive, though. I don't see Hitachi tags discussed below, however. And those are 0.4 mm^2, 2.45 GHz. http://www.hitachi.com/products/material/rfid/rfidprods/index.html says communication distance near-contact (1 cm) for on-chip antenna (the only one useful for in-paper embedding), and 25 cm (potentially up to 1 m), which pretty much settles even the favourable doorframe issue. I agree, for the moment. I'm more worried about where this technology will be five or ten years down the road. ... and run into trouble from salesdroids who won't accept them. Acting dumb (hey, if it looks like cash, it is cash) helps. And if there's no backpressures, before long you'll find yourself strutting down the street sprouting an antenna behind the ear, for the teledetonable implanted cranial explosive (saves on law reinforcement), and a king-size anal probe to boot. Go and read 'Repent Harlequin! Cried the Tick-Tock Man' by PK Dick for a particularly slackless society with this technology. Peter
RE: Detectable cash notes a fantasy
Go and read 'Repent Harlequin! Cried the Tick-Tock Man' by PK Dick for a particularly slackless society with this technology. Might be easier to find if you substitute Harlan Ellison as the author, though. - Sten
Re: Detectable cash notes a fantasy
On Thursday, April 11, 2002, at 07:07 AM, Trei, Peter wrote: [1. Agreed, this thread has lost steam. 2. It always amazes me how often people on this list will handwave and speculate on subjects which a few minutes with Google will settle. Too often, we're like the medieval academics who debated endlessly over how many teeth a horse had, while refusing to go down to the stable to conduct an actual count. ] I didn't handwave and speculate: I said that the detection and antenna problems are enormous. This is borne out by the FAQ you cited, but I didn't need that FAQ to confirm what the physics already tells us. That FAQ does NOT support the claim that stacks of bills may be detected, even with a door-frame-size antenna. --Tim May
Re: Detectable cash notes a fantasy
On Thu, 11 Apr 2002, Eugen Leitl wrote: I could imagine airlines screening for this, though, as a big RFID splash would invite you to become a target for random searches, and a prospective target for confiscation. Better yet, rather than nuke your rfids, try to extract them out of the currency as money passes your hands and collect them. Then place them in some high government official's pocket when they aren't looking.
Re: Detectable cash notes a fantasy
On Wed, 10 Apr 2002, Tim May wrote: How come? True, if a bill is idealized as being planar, you'll have trouble on the plane. Spatial diversity will take care of that. Otherwise, a common note has plenty of surface to do your thing on. Especially at higher frequencies, like UHF and beyond. How come? Because I am assuming the transponders are in the same position on each bill. Why's that? It's easy enough to move the transponder around during the printing process as long as the exact position isn't too important and the number of positions isn't too large. Just have a rotating series of printing plates. If you want to posit some spatial diversity model, that helps, but not but a huge amount. First, spatial diversity is standard terminology for spatially/polarization-wise separated transmitters/receivers, used in order to fight multipath and/or antenna orientation trouble. In closed spaces, that sort of antenna configuration is probably what you'd want, anyway. UHF is hard to launch/receive from a small, planar antenna. UWB is easier to launch from a small ( cm) antenna, but is usually too directional. Who's there to say the antenna has to be cm in size? The chip would have to be, but larger conductive plastic wiring seems to be ideal for antenna work. A stack will interfere, in the sense that planar antennas will couple to each other (radiated signal from A will hit B square on, etc.). So they will. Still, I'm not at all sure one couldn't avoid much of the coupling by moving the antenna around in the bill. And if that's not enough, just build in ad hoc networks. Not too difficult, not too expensive once you've got silicon on-board. Note-to-note, then out. As for the proles being too cheap, too gullible to even bother to lightly shield, sounds like evolution in action. Not really, given that shielding could be outlawed. True money launderers will use shielding. (Actually, this is all oriented at walking around money, so the vast infrastructure will never actually get built, as there is no interest in monitoring trivial amounts.) Who's to say the primary application would be anti-laundering? To me it seems far more likely that low-cost surveillance would be It, even if it's clear that that sort of thing isn't currently doable. I'm done with this thread, though. Too bad. Trimming CC's. Sampo Syreeni, aka decoy - mailto:[EMAIL PROTECTED], tel:+358-50-5756111 student/math+cs/helsinki university, http://www.iki.fi/~decoy/front openpgp: 050985C2/025E D175 ABE5 027C 9494 EEB0 E090 8BA9 0509 85C2
RE: Detectable cash notes a fantasy
On Wed, 10 Apr 2002, Trei, Peter wrote: So, yes, at the moment they can't scan your wallet very easily. But this technology is developing as all others are. I don't know about dealing with many similar tags more or less simultaneously, but some of the discussed apps for stock tracking require dealing with this problem. The tags are passive. All tags (whether inductive or electrostatic) must be energized from the outside. The pumping energy can be shielded, as can the RF emission of the tags itself. The environment is noisy. The tags send simultaneously from the same physical location. I'm not sure whether microwave-pumped digital pulse radio based tags (currently no such technology officially exists) could have a somewhat wider range and less crosstalk, but even then they could be shielded. On this background, the particular technology one uses is not very relevant, as we're talking about limits of physics. Reading secreted banknotes on your body with a magic wand reader is easy (unless wrapped in metal foil), reading them from across the room -- no, sir.
RE: Detectable cash notes a fantasy
On Wed, 10 Apr 2002, Eugen Leitl wrote: The tags are passive. All tags (whether inductive or electrostatic) must be energized from the outside. The pumping energy can be shielded, as can the RF emission of the tags itself. The environment is noisy. The tags send simultaneously from the same physical location. I'm not sure whether microwave-pumped digital pulse radio based tags (currently no such technology officially exists) could have a somewhat wider range and less crosstalk, but even then they could be shielded. On this background, the particular technology one uses is not very relevant, as we're talking about limits of physics. Reading secreted banknotes on your body with a magic wand reader is easy (unless wrapped in metal foil), reading them from across the room -- no, sir. That's true for all RFID stuff, but the next generation the military is looking at is called smart dust. The idea here is to have each speck send info, and the conglomeration of specks adds up to a large signal which can tell you something about the environment (like presense or movement of large metal objects). It's all sci-fi for now, and I think they'll still have to power the things externally so the same shielding applies, but if the bill holds enough transmitters it could have a longer range. But there's no reason a commercial object couldn't have an off switch and power supply built in - the whole wearable computer thing is aimed at that sort of application. All we gotta do is prove to the wealthy they can get more wealthy, and we get to play with the toys :-) Patience, persistence, truth, Dr. mike
RE: Detectable cash notes a fantasy
Michael Motyka[SMTP:[EMAIL PROTECTED]] Tim May [EMAIL PROTECTED] On Tuesday, April 9, 2002, at 10:54 AM, Trei, Peter wrote: Putting RF Tags in cash is one of those ideas with Unintended Consequences. Muggers would love having a way of determining which victims are carrying a wad, as would many salesmen (and JBTs looking to perform a 'civil confiscation' on 'a sum of currency'.) [...] Further, placing the notes in a simple aluminum foil pouch, or a wallet with equivalent lining, would cut any detectable signals by maybe 30-50 dB. Not to mention that if you didn't want your money chirping its presence every time a bad actor pinged it you could just disable the transponder in the money : mechanical pressure or repeated bending high voltage high power RF heat For paper money failure rates will probably be high anyway. Perhaps, perhaps not. Remember, the primary app for this is anti-counterfeiting. Sir: ALL your $20 bills are failing authentication. Please wait while I call Security. Peter
Re: Detectable cash notes a fantasy
Tim May writes: I'll go back to lurking, as this thread, so to speak, is not interesting to me. (More interesting is reading Chris Hillman's page with his Categorical Primer on it, http://www.math.washington.edu/~hillman/papers.html. And to BL and JA, I downloaded O'CAML and picked up a couple of ML texts--I Go away.
Re: Detectable cash notes a fantasy
Trei, Peter wrote: Michael Motyka[SMTP:[EMAIL PROTECTED]] Tim May [EMAIL PROTECTED] On Tuesday, April 9, 2002, at 10:54 AM, Trei, Peter wrote: Putting RF Tags in cash is one of those ideas with Unintended Consequences. Muggers would love having a way of determining which victims are carrying a wad, as would many salesmen (and JBTs looking to perform a 'civil confiscation' on 'a sum of currency'.) [...] Further, placing the notes in a simple aluminum foil pouch, or a wallet with equivalent lining, would cut any detectable signals by maybe 30-50 dB. Not to mention that if you didn't want your money chirping its presence every time a bad actor pinged it you could just disable the transponder in the money : mechanical pressure or repeated bending high voltage high power RF heat For paper money failure rates will probably be high anyway. Perhaps, perhaps not. Remember, the primary app for this is anti-counterfeiting. Sir: ALL your $20 bills are failing authentication. Please wait while I call Security. Peter I thought of this but I felt that at this point it is no longer cash but a fixed-denomination smart card. Currently you can exchange a partial note ( ~50% ) for a new one. There would have to be a mechanism in place for failed electronic bills otherwise people might not be very confident in accepting them. Granted, the inconvenience factor could get high. Mike
Re: Detectable cash notes a fantasy
On Wed, 10 Apr 2002, Tim May wrote: The engineers of such SmartWallets will not give them more range than the protocol needs. Extra range costs money. If Alice is expected to insert her Smart Wallet into a receptacle (for security, if for nothing else), initiating the protocol from several meters away is not in the cards, so to speak. Of course. But when you think of such applications as NID cards, it's likely range is within the spec. Yes, NID's are suspicious enough as they stand. No, people don't see this. Especially after services (or services, it doesn't seem to matter much) start being bound to them -- this is the way Finland, Estonia and a couple of other countries are going, right now, with their electronic ID's. If someone is arguing that such Smart Wallets will merely be passive announcers of bank balances, this is just too naive to waste discussion time on. Good luck selling such a system. Quite. Passive announcers of identity (or signers) with a secondary, enabled mode for actually signing something legally binding, on the other hand... Sampo Syreeni, aka decoy - mailto:[EMAIL PROTECTED], tel:+358-50-5756111 student/math+cs/helsinki university, http://www.iki.fi/~decoy/front openpgp: 050985C2/025E D175 ABE5 027C 9494 EEB0 E090 8BA9 0509 85C2
RE: Detectable cash notes a fantasy
-- From: Tim May[SMTP:[EMAIL PROTECTED]] Sent: Wednesday, April 10, 2002 1:59 PM To: [EMAIL PROTECTED] Subject: Re: Detectable cash notes a fantasy On Wednesday, April 10, 2002, at 09:27 AM, Trei, Peter wrote: For paper money failure rates will probably be high anyway. Perhaps, perhaps not. Remember, the primary app for this is anti-counterfeiting. Sir: ALL your $20 bills are failing authentication. Please wait while I call Security. So, if in fact we _are_ talking about each $20 bill having such a transponder, then why are our arguments about how easy it will be to shield against remote probing not valid? Put the money in a foil packet, or fold it over, or carry it in a stack, or in a standard metal briefcase, and I _guarantee_ that detecting it from afar will be extremely difficult. The argument against shielding is that it is obnoxious that I (or anyone) should have to go even further than I already do to maintain even a fraction of the privacy which was naturally available to every person 150 years ago. Folding the bill won't make any difference. stacking them might make a small difference, if the chips are close enough to detune each other. Some transponders (not the mu-tag, AFAIK) include anti-collision techniques, so many can be detected simultaneously. If a stack of bills containing these transponders are supposed to be read from afar, way beyond what a valid bill detector is likely to be engineered to do, I'd like to see the physics worked out. Detection range turns out to be function of antenna size - the reader's antenna, not the one on the transponder. So if you have a big (eg, doorframe size) antenna, you can do a lot better than the 'valid bill detector' on the countertop. There's actually a privacy win here for the passive tags - the returned signal strength falls with the fourth power of the distance. (A stack of bills, or cards, will have extremely poor radiation patterns from any but the top or bottom bill, and probably their patterns won't be good either.) There's a basic faq at http://www.ti.com/tiris/docs/customerService/faq.htm --Tim May Peter
Re: Detectable cash notes a fantasy
On Wednesday, April 10, 2002, at 11:22 AM, Trei, Peter wrote: The argument against shielding is that it is obnoxious that I (or anyone) should have to go even further than I already do to maintain even a fraction of the privacy which was naturally available to every person 150 years ago. Not to sound too much like Brin, but there was actually very _little_ privacy 150 years ago. Everyone knew who was buying what. Small towns and small neighborhoods. But I digresss... Shielding is much easier than you think, unless shielding is outlawed. Folding the bill won't make any difference. stacking them might make a small difference, if the chips are close enough to detune each other. Some transponders (not the mu-tag, AFAIK) include anti-collision techniques, so many can be detected simultaneously. The anticollision features are in the code, not the antennas. Stacking flat antennas on top of either other is _guaranteed_ to cut the output of any of the inner antennas (and probably the edge antennas) by many, many dB. --Tim May A complex system that works is invariably found to have evolved from a simple system that worked ...A complex system designed from scratch never works and cannot be patched up to make it work. You have to start over, beginning with a working simple system. -- Grady Booch
Re: Detectable cash notes a fantasy
On Wed, Apr 10, 2002 at 02:22:04PM -0400, Trei, Peter wrote: | If a stack of bills containing these transponders are supposed to be | read from afar, way beyond what a valid bill detector is likely to be | engineered to do, I'd like to see the physics worked out. | | Detection range turns out to be function of antenna size - the reader's | antenna, not the one on the transponder. So if you have a big (eg, | doorframe size) antenna, you can do a lot better than the 'valid bill | detector' on the countertop. There's actually a privacy win here for | the passive tags - the returned signal strength falls with the fourth | power of the distance. Interesting. What does that work out to for, say, a 2 meter antenna? (I'm not sure if this actually works out to a security win. It may be that I can use this fast fall-off to ensure that I'm picking the right pocket..) Adam -- It is seldom that liberty of any kind is lost all at once. -Hume
Re: Detectable cash notes a fantasy
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Tim wrote: Everytime I comment on your citations, you go into a snit about how Gramps is insulting the whippersnappers. No, it's all about the condescending tone you take when you use your many years of experience as leverage against anyone who rejects their place in your pecking order. Whether you choose to admit it or not, you're incredibly easygoing on people here who kiss your ass, flatter you, and never dare contradict you out of a fear of retribution. Like the example from a few months ago when you related how somebody asked you if it would be okay to post certain kinds of articles to the group. Why does this please you--don't you want your friends and compatriots to have a fucking backbone? You think you're the only one here who gets to have a spine? Which isn't to say that if the group is set up a certain way, it's right to be inconsiderate of what most people want and expect: for instance, I stopped posting links to news articles when it was made plain to me that most people found it an annoyance. But it wasn't because anyone bullied me into line. If, when I came here, I had made the deliberate choice to make an effort at getting along by emphasizing our similarities instead of differences, I dare say the motivation to dissect-and-destroy every last comment I ever make would be nonexistent. But then, how interesting would that be. For all I know, in Real Life you're older than me, or you're some guy working a guard job at Lockheed. Or both. Ironically enough--but not that it matters--I haven't manufactured any of the details about myself I've given here. I suppose the prudent thing to do would be to encourage people to assume I'm a man (as if I'd have to do anything besides take a neutral nym!) and keep you all looking for the old Lockheed fart, etc. But I suppose it must the grandiosity or vanity or something that compels me to vent under the guise of myself. Which is a pretty funny way to put it actually, since what I say here is far more real than what most people see of me in the real world in a lifetime. Which is probably part of the point anyway. Not that I've given anyone the slightest reason to believe a word of it, but there it is. Yeah yeah, I know--go tell it to Oprah. Or you may be the grad student at Hoboken State College you appear to be. A slur, eh? Not bad. I suspect you're being a little disingenuous though. (If I really were at Hoboken, where's the sting in it?) Ah well, think what you want--I don't have anything to prove. Or shouldn't, anyway. Whatever, I know that your main method of argument is either a bunch of Bah comments followed with cites apropos of nothing you've dug up. Such as your refutation of category theory by digging up some of the usual computer vision and scene analysis junk that's been going around for 40 years. I did no such thing! You asked what happened to general systems theory and expressed a negative view of OR that, though entirely warranted thirty years ago, isn't true of what some people are doing today. So I gave a couple of cites to papers that show how these concepts have been evolving, I thought you might enjoy them. Entirely tangential to the main point of your post, but it's new and it's not junk, damn it. If it's not interesting to you, fine-- but there certainly wasn't any criticism of anything related to you somehow hidden in it. I stand by my comment that shielding a thread in a $100 bill, for example, is vastly easier than detecting it. Your cites about WiFi frequencies and 3 meter ranges and suchlike don't mean much. No of course not, since they were only meant to give a sense of the volume of related research people are doing--hence my only point that 20 years seems a little generous. ~~Faustine. *** He that would make his own liberty secure must guard even his enemy from oppression; for if he violates this duty he establishes a precedent that will reach to himself. - --Thomas Paine -BEGIN PGP SIGNATURE- Version: PGPsdk version 1.7.1 (C) 1997-1999 Network Associates, Inc. and its affiliated companies. (Diffie-Helman/DSS-only version) iQA/AwUBPLSLY/g5Tuca7bfvEQLGigCeOjRDe4ApAZLoTIuGFWxdi/pVTTwAnjjx aObuLmF9JjD+8oGJj2Y2zBoX =lfHT -END PGP SIGNATURE-
Re: Detectable cash notes a fantasy
On Wed, Apr 10, 2002 at 10:59:32AM -0700, Tim May wrote: | On Wednesday, April 10, 2002, at 09:27 AM, Trei, Peter wrote: | For paper money failure rates will probably be high anyway. | So, if in fact we _are_ talking about each $20 bill having such a | transponder, then why are our arguments about how easy it will be to | shield against remote probing not valid? Put the money in a foil packet, | or fold it over, or carry it in a stack, or in a standard metal | briefcase, and I _guarantee_ that detecting it from afar will be | extremely difficult. | | If a stack of bills containing these transponders are supposed to be | read from afar, way beyond what a valid bill detector is likely to be | engineered to do, I'd like to see the physics worked out. | | (A stack of bills, or cards, will have extremely poor radiation patterns | from any but the top or bottom bill, and probably their patterns won't | be good either.) Does it matter? Intuitively, you broadcast a radio signal, and pick up from that where the largest clusters of bills are. Repeat several times if needed. You don't care about signal accuracy, just magnitude. You then decide if the people with wads of cash look like an easy mugging target. Adam -- It is seldom that liberty of any kind is lost all at once. -Hume
Re: Detectable cash notes a fantasy
On Wed, 10 Apr 2002, Tim May wrote: So, if in fact we _are_ talking about each $20 bill having such a transponder, then why are our arguments about how easy it will be to shield against remote probing not valid? Because the economics do not work. People simply aren't knowledgeable/interested enough to actually shield their notes, even if this would only imply buying a foil-shielded wallet. Especially if such wallets are outlawed. (Yes, this is starting to sound like too much, even if governments don't always behave rationally.) (A stack of bills, or cards, will have extremely poor radiation patterns from any but the top or bottom bill, and probably their patterns won't be good either.) How come? True, if a bill is idealized as being planar, you'll have trouble on the plane. Spatial diversity will take care of that. Otherwise, a common note has plenty of surface to do your thing on. Especially at higher frequencies, like UHF and beyond. Sampo Syreeni, aka decoy - mailto:[EMAIL PROTECTED], tel:+358-50-5756111 student/math+cs/helsinki university, http://www.iki.fi/~decoy/front openpgp: 050985C2/025E D175 ABE5 027C 9494 EEB0 E090 8BA9 0509 85C2
Re: Detectable cash notes a fantasy
On Wednesday, April 10, 2002, at 12:25 PM, Sampo Syreeni wrote: On Wed, 10 Apr 2002, Tim May wrote: (A stack of bills, or cards, will have extremely poor radiation patterns from any but the top or bottom bill, and probably their patterns won't be good either.) How come? True, if a bill is idealized as being planar, you'll have trouble on the plane. Spatial diversity will take care of that. Otherwise, a common note has plenty of surface to do your thing on. Especially at higher frequencies, like UHF and beyond. How come? Because I am assuming the transponders are in the same position on each bill. If you want to posit some spatial diversity model, that helps, but not but a huge amount. This sounds too science fictionish to actually deploy (transponders are not the same as letters, and cannot be moved around on a random basis). UHF is hard to launch/receive from a small, planar antenna. UWB is easier to launch from a small ( cm) antenna, but is usually too directional. A stack will interfere, in the sense that planar antennas will couple to each other (radiated signal from A will hit B square on, etc.). As for the proles being too cheap, too gullible to even bother to lightly shield, sounds like evolution in action. Actually, more to the point, it means that the vast infrastructure of remote bill readers will, perforce, pick up the proles. True money launderers will use shielding. (Actually, this is all oriented at walking around money, so the vast infrastructure will never actually get built, as there is no interest in monitoring trivial amounts.) I'm done with this thread, though. --Tim May They played all kinds of games, kept the House in session all night, and it was a very complicated bill. Maybe a handful of staffers actually read it, but the bill definitely was not available to members before the vote. --Rep. Ron Paul, TX, on how few Congresscritters saw the USA-PATRIOT Bill before voting overwhelmingly to impose a police state
RE: Detectable cash notes a fantasy
30 seconds in a microwave on high, stir and rotate tray... -Original Message- From: Michael Motyka [mailto:[EMAIL PROTECTED]] Sent: Wednesday, April 10, 2002 8:24 AM To: [EMAIL PROTECTED] Subject: Re: Detectable cash notes a fantasy Tim May [EMAIL PROTECTED] On Tuesday, April 9, 2002, at 10:54 AM, Trei, Peter wrote: Putting RF Tags in cash is one of those ideas with Unintended Consequences. Muggers would love having a way of determining which victims are carrying a wad, as would many salesmen (and JBTs looking to perform a 'civil confiscation' on 'a sum of currency'.) Physics-wise, it's a jiveass fantasy. No way are there micro-strips readable from a distance in today's currency, and very likely not in the next 20 years. (I don't dispute that a careful lab setup could maybe read a note at a few meters, in a properly-shielded environment, without any shieding between note and detectors, and with enough time and tuning. But a wad of bills, folded, stuffed, and with little time to make the detection...an altogether different kettle of fish.) Further, placing the notes in a simple aluminum foil pouch, or a wallet with equivalent lining, would cut any detectable signals by maybe 30-50 dB. Or more. Not to mention that if you didn't want your money chirping its presence every time a bad actor pinged it you could just disable the transponder in the money : mechanical pressure or repeated bending high voltage high power RF heat For paper money failure rates will probably be high anyway. --Tim May I'm guessing that electronic tracking or outright elimination of cash would be coupled with a surge in the use of barter and alternative monies. Mike
Re: Detectable cash notes a fantasy
On Tue, 9 Apr 2002, Tim May wrote: Physics-wise, it's a jiveass fantasy. No way are there micro-strips readable from a distance in today's currency, and very likely not in the next 20 years. (I don't dispute that a careful lab setup could maybe read a note at a few meters, in a properly-shielded environment, without any shieding between note and detectors, and with enough time and tuning. But a wad of bills, folded, stuffed, and with little time to make the detection...an altogether different kettle of fish.) Further, placing the notes in a simple aluminum foil pouch, or a wallet with equivalent lining, would cut any detectable signals by maybe 30-50 dB. That solves the theives problem :-) And you wouldn't need a wad, that's the whole point. You'd just need 1. It could transfer money just like a smart card. But I'll grant it's science fiction at this point. Maybe a smart card that has the weight of a gold coin with some thickness to it would work better. For the filthy rich, make the outside real gold! The rest of us can use brass. I still think the basic problem is simple - how do you trust the bits? If the actual computations are done inside a secure box, most people will trust it. There will always be people who try to beat the system, but it'll take a lot of technology, and they'll do it often enough to get caught (most theives simply don't want to pass up a good deal when they invent one :-) The actual structure of the box doesn't matter - a floppy cloth bill or thick coin is still a computer. Who makes and distributes it is what matters. Patience, persistence, truth, Dr. mike
