NODE 4efeabf1CD-reading for random keys
knapper@bga.com (Woodrow W. Baker)Wed, 13 Mar 1996 17:53:35 +0800
Doe anyone know where sample code exists to enable one to read the digital
stream from an audio CD? If so, I'd appreciate some pointers to it via
email. It seems to me like an Audio Cd would make the perfect one-time
crypto system. You merely start reading at a specific spot, tossing away
bytes using a reproducable random number generator, then permuting
those to form a XOR one time key of any length you want. All that would be
required to decrypt it would be a CD, the starting point, and the
encryption/decryption software. The first step is to be able to read an
arbitray sequence of digital samples from an arbitrary spot on a CD. I'm
currently looking for software (perferably source) to enable me to do that.
Cheers
Woody
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NODE ea794181Re: CD-reading for random keys
sonicpty@sirius.com (Sonic Purity)Sat, 23 Mar 1996 16:07:27 +0800
In article <4i91h4$lp5@nero.omega.co.nz>, bruce@omega.co.nz wrote:
>>Doe anyone know where sample code exists to enable one to read the digital
>>stream from an audio CD? <edit>
>>crypto system. You merely start reading at a specific spot, tossing away
>>bytes using a reproducable random number generator, then permuting
>>those to form a XOR one time key of any length you want.
>
>The "entropy" or randomness of audio data is LOW. That's why audio compresses
>so well. However, the idea of keeping a one-time key on CD-ROM is good.
CD-ROM--good. CD-Audio--weeeelll...could be trouble. Keep in mind Red
Book audio does not require 100% error correction, so it would be pretty
likely the keys would not match given the tiniest data hiccup. A data mode
should work (i'd think).
<edit>Then you can send up to 600M of totally secure data before you
>dispose of the disks (Microwave oven is fun :) and write a new pair.
3-4 sec. on High; no more, no less. Remove the oven bulb beforehand for
best viewing:)
))Sonic((
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NODE 0627fba5CD-reading for random keys
bruce@omega.co.nzThu, 14 Mar 1996 14:16:18 -0500
>Doe anyone know where sample code exists to enable one to read the digital
>stream from an audio CD? If so, I'd appreciate some pointers to it via
>email. It seems to me like an Audio Cd would make the perfect one-time
cdgrab (registered) will let you read "frames" (1/75sec of audio) directly into
a wav file. From there it's easy.. But:
>crypto system. You merely start reading at a specific spot, tossing away
>bytes using a reproducable random number generator, then permuting
>those to form a XOR one time key of any length you want.
The "entropy" or randomness of audio data is LOW. That's why audio compresses
so well. However, the idea of keeping a one-time key on CD-ROM is good. I would
suggest recording thermal noise (Eg the hiss from an untuned FM radio), perhaps
XORing with a pseudo-random sequence to remove residual bias. Record 600M of
this onto a pair of writable CDs, and have your friend come and collect one of
them personally. Then you can send up to 600M of totally secure data before you
dispose of the disks (Microwave oven is fun :) and write a new pair.
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