DalSemi: Add-Only Memory for Storage of Digital Cash
A press release breezed through the list a while back about some "decoder rings" -- basically, a nonvolatile RAM chip embedded in a Jostens ring. On further inspection, it looks to be a superior product to the DataKey products I remember seeing about ten years ago, targeted at this same sort of niche. The part in question is much smaller -- it fits in a ring, after all, or on the usual sorts of key fobs and employee badges -- and establishing electrical contact to transceive data is trivial. Cypherpunks relevance? Twofold. One, the Touch MultiKey (ftp://ftp.dalsemi.com/pub/datasheets/1991.ps), which promises to hold three 384 bit blocks under 64-bit passwords. The device will transmit the stored data under the correct password, and "random bits" under all other passwords. No crypto here, though, just a simple on-chip comparison with a stored password. So I assume the determined opponent with physical access can extract the info; but better that than store your private key on a publically accessible machine, no? Secondly, an app note: "Use of Add-Only Memory for Secure Storage of Monetary Equivalent Data" (ftp://ftp.dalsemi.com/pub/datasheets/app84.ps). A creative idea based on the peculiar nature of the EPROMs* that are also available in this form factor. In particular, one bits may be burned to zeros, but not vice versa; so why not burn particular bits to indicate credits and debits? Knowing that this scheme depends on keeping an attacker from guessing which bits to burn, they use the unique serial number to uniquely permute the bits, so that an attacker is as likely to burn a "debit" bit as a "credit", and far likelier to burn out-of-sequence so that the monkey business is apparent to any vendor. And there's another item of note: each chip has a unique, etched, machine-readable serial number. What are the bets that Dallas Semiconductor can tell you who purchased that chip? Well, so much for an anonymous payment scheme based on *this* product. Still, if I had to choose a place to keep a secret key, I'd choose my knuckle over my key ring, let alone a floppy disk, PDA, or portable computer. nathan * Gee, back in my day EPROMs were Eraseable; these folks mean instead to indicate an Electrically Programmable chip, which sounds like a good old PROM to me. Ahhh, acronyms...
Nathan Loofbourrow writes:
And there's another item of note: each chip has a unique, etched, machine-readable serial number. What are the bets that Dallas Semiconductor can tell you who purchased that chip? Well, so much for an anonymous payment scheme based on *this* product.
Some enterprising cypherpunks can buy a bunch and resell 'em for cash.
On Tue, 17 Oct 1995, Scott Brickner wrote:
Nathan Loofbourrow writes:
And there's another item of note: each chip has a unique, etched, machine-readable serial number. What are the bets that Dallas Semiconductor can tell you who purchased that chip? Well, so much for an anonymous payment scheme based on *this* product.
Some enterprising cypherpunks can buy a bunch and resell 'em for cash.
And then sell the serial address for cash. How do I know that they (this means YOU! :> ) don't work for the company? (which is a contracter for, blackmail-victim of, tentacle of NSA, CSE, TCMAY, Purplenet, your fairy-stepmother ...) Of course there's always the mail-drop & forward-net... (anyone one know maildrop company addresses, the possible (il)legality of these things or any reported monitoring cases? A physical remailernet might come to matter in an economy where the "split" between an untaxable info economy and a taxable physical economy become pronounced. Though it's kinda hard to encrypt and reorder packages.)
s1018954@aix2.uottawa.ca writes:
On Tue, 17 Oct 1995, Scott Brickner wrote:
Nathan Loofbourrow writes:
And there's another item of note: each chip has a unique, etched, machine-readable serial number. What are the bets that Dallas Semiconductor can tell you who purchased that chip? Well, so much for an anonymous payment scheme based on *this* product.
Some enterprising cypherpunks can buy a bunch and resell 'em for cash.
And then sell the serial address for cash. How do I know that they (this means YOU! :> ) don't work for the company? (which is a contracter for, blackmail-victim of, tentacle of NSA, CSE, TCMAY, Purplenet, your fairy-stepmother ...)
Big deal. NSA now knows "someone bought address X". That's the great thing about cash you know... anonymity.
Someone said:
Some enterprising cypherpunks can buy a bunch and resell 'em for cash.
And then sell the serial address for cash.
CypherChip Party. Pick up one chip from pile and leave one chip, or leave $$. -- A host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that's close........[v].(301) 56-LINUX Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433
-----BEGIN PGP SIGNED MESSAGE----- In list.cypherpunks, loofbour@cis.ohio-state.edu writes:
And there's another item of note: each chip has a unique, etched, machine-readable serial number. What are the bets that Dallas Semiconductor can tell you who purchased that chip? Well, so much for an anonymous payment scheme based on *this* product.
Dallas might be able to tell who purchased them, but it's likely to have been someone like Hamilton-Hallmark (a major parts distributor). Whether the distributors are going to maintain the audit trail is questionable at best. It only takes one distributor to break the chain of traceability, and audit trails cost money.
* Gee, back in my day EPROMs were Eraseable; these folks mean instead to indicate an Electrically Programmable chip, which sounds like a good old PROM to me. Ahhh, acronyms...
This comes from the fact that PROMs are typically mask-programmed at the fabrication stage. EPROMS are programmed in the field. And yes, if you could get the top of the chip off cleanly, you could erase and reprogram them. (not likely, and hardly undetectable, but it's ever so slightly possible) More often, I see these devices called OTP (for One Time Programmable). In the more standard types (27C256, for example), they're a fraction of the cost of the erasable ones. Ceramic cases and quartz windows are spendy. - -- Roy M. Silvernail [ ] roy@cybrspc.mn.org PGP Public Key fingerprint = 31 86 EC B9 DB 76 A7 54 13 0B 6A 6B CC 09 18 B6 Key available from pubkey@cybrspc.mn.org -----BEGIN PGP SIGNATURE----- Version: 2.6.2 iQCVAwUBMIQv0Rvikii9febJAQEeKAP+LbgyZ/60fGuVICZEqM+Rv34GhEA6a/vg cKPbKCazUVg8bEBod3mqbHfssjDgD47PcAai8uM3ALmki/TI3DfI6FLbZr7aCpa8 PSNFDTEpmRDpnm5xpbZa/5O1aLdXLX6ps8OGsg0YjY1hvFQCn5tymW9GjhOXrkXS s698T5nEoQI= =LoNA -----END PGP SIGNATURE-----
Roy Silvernail writes:
This comes from the fact that PROMs are typically mask-programmed at the fabrication stage. EPROMS are programmed in the field. And yes, if you could get the top of the chip off cleanly, you could erase and reprogram them. (not likely, and hardly undetectable, but it's ever so slightly possible) More often, I see these devices called OTP (for One Time Programmable). In the more standard types (27C256, for example), they're a fraction of the cost of the erasable ones. Ceramic cases and quartz windows are spendy.
Perhaps someone with more semiconductor physics background can correct me, but my understanding is that some kinds of nuclear radiation can be used to erase OTP EPROMS. I suppose this might damage the crystal lattice badly enough to render the device useless in some bit positions or reduce data retention time a lot, but I sure wouldn't bet any security on devices out there not being arbitrarily reprogrammable (thus using bits to represent digital coins in a wallet that get reset when they are spent is not a good idea). Dave Emery die@die.com
Roy Silvernail writes:
This comes from the fact that PROMs are typically mask-programmed at the fabrication stage. EPROMS are programmed in the field. And yes, if you could get the top of the chip off cleanly, you could erase and reprogram them. (not likely, and hardly undetectable, but it's ever so slightly possible) More often, I see these devices called OTP (for One Time Programmable). In the more standard types (27C256, for example), they're a fraction of the cost of the erasable ones. Ceramic cases and quartz windows are spendy.
Perhaps someone with more semiconductor physics background can correct me, but my understanding is that some kinds of nuclear radiation can be used to erase OTP EPROMS. I suppose this might damage the crystal lattice badly enough to render the device useless in some bit positions or reduce data retention time a lot, but I sure wouldn't bet any security on devices out there not being arbitrarily reprogrammable (thus using bits to represent digital coins in a wallet that get reset when they are spent is not a good idea). Dave Emery die@die.com
Roy Silvernail writes:
This comes from the fact that PROMs are typically mask-programmed at the fabrication stage. EPROMS are programmed in the field. And yes, if you could get the top of the chip off cleanly, you could erase and reprogram them. (not likely, and hardly undetectable, but it's ever so slightly possible) More often, I see these devices called OTP (for One Time Programmable). In the more standard types (27C256, for example), they're a fraction of the cost of the erasable ones. Ceramic cases and quartz windows are spendy.
Perhaps someone with more semiconductor physics background can correct me, but my understanding is that some kinds of nuclear radiation can be used to erase OTP EPROMS. I suppose this might damage the crystal lattice badly enough to render the device useless in some bit positions or reduce data retention time a lot, but I sure wouldn't bet any security on devices out there not being arbitrarily reprogrammable (thus using bits to represent digital coins in a wallet that get reset when they are spent is not a good idea). Dave Emery die@die.com
Roy Silvernail writes:
This comes from the fact that PROMs are typically mask-programmed at the fabrication stage. EPROMS are programmed in the field. And yes, if you could get the top of the chip off cleanly, you could erase and reprogram them. (not likely, and hardly undetectable, but it's ever so slightly possible) More often, I see these devices called OTP (for One Time Programmable). In the more standard types (27C256, for example), they're a fraction of the cost of the erasable ones. Ceramic cases and quartz windows are spendy.
Perhaps someone with more semiconductor physics background can correct me, but my understanding is that some kinds of nuclear radiation can be used to erase OTP EPROMS. I suppose this might damage the crystal lattice badly enough to render the device useless in some bit positions or reduce data retention time a lot, but I sure wouldn't bet any security on devices out there not being arbitrarily reprogrammable (thus using bits to represent digital coins in a wallet that get reset when they are spent is not a good idea). Dave Emery die@die.com
Roy Silvernail writes:
This comes from the fact that PROMs are typically mask-programmed at the fabrication stage. EPROMS are programmed in the field. And yes, if you could get the top of the chip off cleanly, you could erase and reprogram them. (not likely, and hardly undetectable, but it's ever so slightly possible) More often, I see these devices called OTP (for One Time Programmable). In the more standard types (27C256, for example), they're a fraction of the cost of the erasable ones. Ceramic cases and quartz windows are spendy.
Perhaps someone with more semiconductor physics background can correct me, but my understanding is that some kinds of nuclear radiation can be used to erase OTP EPROMS. I suppose this might damage the crystal lattice badly enough to render the device useless in some bit positions or reduce data retention time a lot, but I sure wouldn't bet any security on devices out there not being arbitrarily reprogrammable (thus using bits to represent digital coins in a wallet that get reset when they are spent is not a good idea). Dave Emery die@die.com
Roy Silvernail writes:
This comes from the fact that PROMs are typically mask-programmed at the fabrication stage. EPROMS are programmed in the field. And yes, if you could get the top of the chip off cleanly, you could erase and reprogram them. (not likely, and hardly undetectable, but it's ever so slightly possible) More often, I see these devices called OTP (for One Time Programmable). In the more standard types (27C256, for example), they're a fraction of the cost of the erasable ones. Ceramic cases and quartz windows are spendy.
Perhaps someone with more semiconductor physics background can correct me, but my understanding is that some kinds of nuclear radiation can be used to erase OTP EPROMS. I suppose this might damage the crystal lattice badly enough to render the device useless in some bit positions or reduce data retention time a lot, but I sure wouldn't bet any security on devices out there not being arbitrarily reprogrammable (thus using bits to represent digital coins in a wallet that get reset when they are spent is not a good idea). Dave Emery die@die.com
participants (6)
-
Dave Emery -
David Lesher -
Nathan Loofbourrow -
roy＠cybrspc.mn.org -
s1018954＠aix2.uottawa.ca -
Scott Brickner