[Cryptography] Best internet crypto clock

Jerry Leichter leichter at lrw.com
Tue Oct 21 14:40:33 EDT 2014

On Oct 21, 2014, at 1:02 PM, Bear <bear at sonic.net> wrote:
> 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. 
That's a cool technique.  Do you have any references?

                                                        -- Jerry

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