NODE fd7c0690Re: Computerized OTP (was 5th AMENDMENT & DECRYPTION)
Marc.Ringuette@GS80.SP.CS.CMU.EDUTue, 26 Jan 93 11:46:37 PST
thug@phantom.com (Murdering Thug) writes,
> A person I know is working on a computerized version of the OTP that
> extracts a truly random stream of bits from TV/RF static and massages it
> using a DSP to be highly variable (e.g.: no runs of 0's or 1's longer than
> 5 bits).
Cool! You've managed to weaken the one time pad enough for someone to
crack it! [ I can collect statistics on the plaintext based on the fact
that if five zeroes occur in the OTP then the next bit is constrained to
be one. Of course, I don't have complete access to the OTP, but it's
an extremely useful statitistical foot-in-the-door. ]
This failure occurred because your friend tried to create a number
sequence that is somehow "more random than random". Such a sequence
is, by definition, weak.
-- Marc Ringuette (mnr@cs.cmu.edu)
NODE 2f3ce428Computerized OTP (was 5th AMENDMENT & DECRYPTION)
Eric Hughes <hughes@soda.berkeley.edu>Tue, 26 Jan 93 19:36:42 PST
>thug@phantom.com (Murdering Thug) writes,
>> (e.g.: no runs of 0's or 1's longer than
>> 5 bits).
>Cool! You've managed to weaken the one time pad enough for someone to
>crack it!
Taking 6-graph statistics, we seen that the entropy is 5.95, where it
should be 6.00. Or in other words, .992 bits of entropy per bit
symbol. That's not good.
Eric