Back in the late 60's I was playing with audio and a magazine I subscribed to had a circut for creating warble tones for standing wave and room resonance testing.
The relevance of this is that they were using a "random" noise generating chip that they acknowledged was not random enough for good measurements. The fix suggested was to parallel a number, six as I recall, to improve the randomness by mixing the signals to achieve better randomness. I don't recall the math but the approach improved the randomness by more than an order of magnitude. I have also seen the same effect on reverse biased zener diodes used as random noise generators and that seemed - no real hard measurements that I can recall - to work quite well. Mind you these were not zeners all fabricated on a single chip, but rather individuals soldered together so the charateristics of each were more random because of the semi-randomness of the manufacturing process. Perhaps a similar approach could be used here. Best, Allen --------- Original Message -------- From: Udhay Shankar N <[EMAIL PROTECTED]> To: cryptography@metzdowd.com <cryptography@metzdowd.com> Subject: using SRAM state as a source of randomness Date: 09/12/07 11:03 > > Sounds like an interesting idea - using SRAM state as a source of > randomness. Any of the folks here willing to comment on this? > > Udhay > > http://prisms.cs.umass.edu/~kevinfu/papers/holcomb-FERNS-RFIDSec07.pdf > > Initial SRAM State as a Fingerprint and Source > of True Random Numbers for RFID Tags > > Daniel E. Holcomb, Wayne P. Burleson, and Kevin Fu > University of Massachusetts, Amherst MA 01002, USA, > {dholcomb, [EMAIL PROTECTED], [EMAIL PROTECTED] > http://www.rfid-cusp.org/ > > Abstract. > > RFID applications create a need for low-cost security and > privacy in potentially hostile environments. Our measurements show > that initialization of SRAM produces a physical fingerprint. We propose > a system of Fingerprint Extraction and Random Numbers in SRAM > (FERNS) that harvests static identity and randomness from existing > volatileCMOSstorage.Theidentityresultsfrommanufacture-timephys- > icallyrandomdevicethresholdmismatch,andtherandomnumbersresult > from run-time physically random noise. We use experimental data from > virtual tags, microcontroller memory, and the WISP UHF RFID tag to > validate the principles behind FERNS. We show that a 256byte SRAM > can be used to identify circuits among a population of 160 virtual tags, > and can potentially produce 128bit random numbers capable of passing > cryptographic statistical tests. > > > -- > ((Udhay Shankar N)) ((udhay @ pobox.com)) ((www.digeratus.com)) > > --------------------------------------------------------------------- > The Cryptography Mailing List > Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED] > ________________________________________________ Message sent using UebiMiau 2.7.10 --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]