Messages in this thread | | | Date | Mon, 12 Jan 2004 01:19:32 -0500 | From | "Stephen D. Williams" <> | Subject | Re: High Quality Random sources, was: Re: SecuriKey |
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It has puzzled me for a while why it doesn't occur to people that a high quality OTP is a high quality source of shared private keys for a good symmetric algorithm. That is a much better use than 1-to-1 XOR. Sure, you're still only as secure as the symmetric algorithm but if you can manage distribution of a OTP, you don't have to otherwise worry about key management other than walking through the keys so that they are only used once. 128MB+ (or 200MB or 1GB) represents a lot of AES keys. With that many, you could just skip around on a non-key aligned random point (using your high-quality random source of course ;-) ), transmit the point you are using as a key selector, and not worry about avoiding reuse management.
PKI is better for many reasons, but it's still interesting that an essentially low-tech technique like OTP could be used in a similar way. You still have an N^2 key exchange problem that PKI solves.
sdw
Valdis.Kletnieks@vt.edu wrote:
>On Sun, 11 Jan 2004 23:10:47 EST, "Stephen D. Williams" said: > > > >>OTP absolutely requires that you share the OTP out of band, i.e. you >>twin a capture of random data. Any transfer makes it as vulnerable as >>the transfer method. >> >> > >The single most common OTP-related offense of Schneier's "snake oil crypto" >has got to be the fact it's almost never only used exactly once and then discarded. > >So sure you can load 200 meg of OTP into the dongle before you leave the spy agency >on a mission. The fun starts when you get to the 201st megabyte of data. :) > >
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