[Cryptography] Best internet crypto clock

[Jerry Leichter]

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

-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/pkcs7-signature
Size: 4813 bytes
Desc: not available
URL: <http://www.metzdowd.com/pipermail/cryptography/attachments/20141021/5918a746/attachment.bin>