Date: Wed, 22 Jun 2005 01:07:39 -0700 (PDT) From: Arne "Wörner" <arne_woerner@yahoo.com> To: Jacob Meuser <jakemsr@jakemsr.com>, freebsd-multimedia@freebsd.org Subject: Re: tamper proofing audio Message-ID: <20050622080739.67493.qmail@web41214.mail.yahoo.com> In-Reply-To: <20050622051314.GB23165@puff.jakemsr.gom>
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--- Jacob Meuser <jakemsr@jakemsr.com> wrote: > On Wed, Jun 22, 2005 at 02:12:20PM +0930, Tim Aslat wrote: > > Hi All, > > > > can anyone tell me if it's possible to tamper-proof an > > audio recording in such a way that it can still be > > played on a normal audio CD player? > > > Simply verifying the files with checksums (multiple > algorithms to lessen the possibility of "collision > attacks") is insufficient? > I say, how could we hinder an attacker to simply recompute the checksum after modifying the audio recording? gnupg (ports/security) would provide a signature, that is coupled with a passphrase. Since I do not like passphrases, because they can be found out quite easily (the trick with just asking for the passphrase sometimes still works, too), I would say that you need a physically safe computer somewhere (with tall muscled guards and pump-guns) - on this computer you could store the signatures or -even better- the whole audio recording (I just remember that you do not have a network connection...)... Another idea would be, that you produce the check-sum/signature for the recording and then the computer asks the lawyer/person to read the checksum to the computer - then the computer adds that check-sum recording to the to-be-signed recording, so that the attacker would have at least the problem of simulating the voice of the lawyer/person, which might be quite impossible... -Arne P. S.: It remembers me a little bit on the silly lawyer in the TV series "The Simpsons", who used to change the video/audio last will of his clients by simply using his own voice... *giggle* __________________________________ Yahoo! Mail Mobile Take Yahoo! Mail with you! Check email on your mobile phone. http://mobile.yahoo.com/learn/mail
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