Vulnerability Development mailing list archives
Re: SDMI - The way I would make the water mark.
From: Ben Galehouse <bgalehou () PACBELL NET>
Date: Sat, 14 Oct 2000 11:48:03 -0700
Steve Mosher wrote:
Given two copies of the same audio, but with different watermarks, you can still (at least) corrupt the watermark by averaging or what have you. I'm not as good with DSP as I'd like to be, but I'm sure you'd also have to be wary of harmonics and other fun stuff this way. It might also bugger up hi-fi sound, binaural sound and sound sourcing effect, depending on exactly how it's implemented.
Suppose that the watermark invloved changing every 30th second of the music. (i.e., 1 second of every 30 was marked). Suppose that the initial offset was random. Then averaging would just merge the marks. The mark becoems weaker, eventually becoming noise, but if your number of copies were limited (i.e. you had to pay for each), it might not be easy to defeat that way. Alright, that particular system would be pretty easy to defeat with three differently marked filed and a good binary diff program, but there are probably better systems with an analogous property.
Current thread:
- hacksdmi? Blue Boar (Oct 11)
- Re: hacksdmi? Ralph Moonen (Oct 11)
- Re: hacksdmi? Masial (Oct 12)
- Re: hacksdmi? Daniel Petzen (Oct 13)
- Re: hacksdmi? Steve Mosher (Oct 13)
- SDMI - The way I would make the water mark. Richard Rager (Oct 13)
- Re: SDMI - The way I would make the water mark. Robert Collins (Oct 13)
- Re: SDMI - The way I would make the water mark. buggz (Oct 13)
- Re: SDMI - The way I would make the water mark. Steve Mosher (Oct 13)
- Re: SDMI - The way I would make the water mark. Ben Galehouse (Oct 14)
- Re: hacksdmi? Masial (Oct 12)
- Re: SDMI - The way I would make the water mark. Bluefish (P.Magnusson) (Oct 14)
- Re: hacksdmi? Ralph Moonen (Oct 11)
- Re: hacksdmi? Ralph Moonen (Oct 13)
- Re: hacksdmi? Masial (Oct 13)
- Re: hacksdmi? spiff (Oct 14)
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- Re: SDMI - The way I would make the water mark. Ralph Moonen (Oct 14)
- Re: hacksdmi? Steve Mosher (Oct 12)
- Re: hacksdmi? David Knaack (Oct 12)
- Re: hacksdmi? Robert Johnson (Oct 13)