On Sun, 1 Jan 2006, coderman wrote:
(4) For any form of time-destruction messaging to really work, the keying information would have to be tied to a physical <something> that cannot be reclaimed, and which decays at a fixed, known, and closely approximatable rate (a radiodecay probably doesn't meet this criteria);
Every time-sensitive auto-destructing system Ive seen discussed here fails these weaknesses.
this doesn't provide time destruction so i assume this is in reference to Tyler's description. you could couple the user authentication with a physically hardened token of some sort for access to the pads but even this would require manual destruction.
do they make physically hardened authentication tokens with timed self destruction built in?
Not that I am aware of, and if they did, I would by definition not trust them. I want my time-limited key to be some natural phenomenon that cannot be recreated after it "dies", but which is "readable" (for keying) and stable for a known time interval. Is there radioactive material which has has a known property that can be reliably and repetitively measured, that is useful as either a key or a seed, and that is guaranteed to change on a known schedule in a significant (i.e., keying data no longer relevant) way? The idea being something like msg xor radioseed "keys" = plaintext, but after 30 days, radioseed is different (and the original not knowable), and therefore message is dead. -- Yours, J.A. Terranson sysadmin@mfn.org 0xBD4A95BF 'The right of self defence is the first law of nature: in most governments it has been the study of rulers to confine this right within the narrowest limits possible. Wherever standing armies are kept up, and the right of the people to keep and bear arms is, under any colour or pretext whatsoever, prohibited, liberty, if not already annihilated, is on the brink of destruction.' St. George Tucker