[Cryptography] Best internet crypto clock

Bear bear at sonic.net
Tue Oct 21 13:02:33 EDT 2014

IIRC a lot has been done to verify video and audio as having come 
from a certain moment in time or general location based on recovering
the precise 'drift' of the omnipresent 60-cycle (or 50-cycle if 
you're Australian) hum of the surrounding electrical system.  While 
it's fairly precise, it's not exact, and over very widespread areas 
the exact frequency and interference patterns recovered from a video 
or audio record have been used to determine exactly when (and to some 
extent where) the record was made.  

Relevant law enforcement and Intel agencies are, yes, known to monitor 
and record the variances specifically for purposes of dating recordings
that later may become evidence. 


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