Markus Kuhn has released this after learning of Joe Loughry's announcement.
----- Announced 5 March 2002. To be presented at IEEE Oakland conference, May 2002 http://www.cl.cam.ac.uk/~mgk25/ieee02-optical.pdf Optical Time-Domain Eavesdropping Risks of CRT Displays Markus G. Kuhn University of Cambridge, Computer Laboratory JJ Thomson Avenue, Cambridge CB3 0FD, UK [EMAIL PROTECTED] Abstract A new eavesdropping technique can be used to read cathode-ray tube (CRT) displays at a distance. The intensity of the light emitted by a raster-scan screen as a function of time corresponds to the video signal convolved with the impulse response of the phosphors. Experiments with a typical personal computer color monitor show that enough high-frequency content remains in the emitted light to permit the reconstruction of readable text by deconvolving the signal received with a fast photosensor. These optical compromising emanations can be received even after diffuse reflection from a wall. Shot noise from background light is the critical performance factor. In a sufficiently dark environment and with a large enough sensor aperture, practically significant reception distances are possible. This information security risk should be considered in applications with high confidentiality requirements, especially in those that already require �TEMPEST�-shielded equipment designed to minimize radio-frequency emission-security concerns. ----- --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]
