Re:Game of Thrones leak and watermark: a stupid tracking system
by mitchell_h on Monday April 13, 2015 @10:00AM
(#9367607)
Wouldn't a simple re-encode break any sort of stenography?
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Re:Game of Thrones leak and watermark: a stupid tracking system
by fredley on Monday April 13, 2015 @10:05AM
(#9367654)
No. There are algorithms out there that can survive compression[1] by encoding statistically over an image instead of just bit manipulation.
You can also embed data in the audio channel by alternating between two imperceptible echo kernels for 1/0[2]. This is extremely compression resistant.
1: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=&arnumb...
2: http://www.slidefinder.net/a/audio_steganography_echo_data_h...
Re:Game of Thrones leak and watermark: a stupid tracking system
by psk on Monday April 13, 2015 @10:07AM
(#9367661)
Surely it would be possible to create encoding resistant stenography. Will the stenography be affected, sure, but it should be possible to create error-resistant stenography up to a certain point.
Re:Game of Thrones leak and watermark: a stupid tracking system
by dTal on Wednesday April 15, 2015 @11:56AM
(#9381812)
Stenography: encode information such that it is below the human detection threshold.
Lossy compression: discard all sub-threshold information.
Thus, in the general case it's fundamentally impossible. You can make a scheme that will survive certain known encoders and bitrates, but you can't make one that will survive all lossy compression.