Re: Time Expiry Alogorithm??

["Gary E. Miller" <gem () rellim com>]

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Yo Gautum!

On Fri, 19 Nov 2004, Gautam R. Singh wrote:

> I was just wondering is there any encrytpion alogortim which expires wit
> h time.

IPSec, kerboros, etc. all use time as part of the auto-generated session
key to prevent playback attacks.

If a black hat has an intercepted message he wants to decode then he can
set his clock to anything he wants to.  Time is no help there, except
to expand the key search space if they are looking for an unknown key.
If they have the key already nothing you can do if they can reset their
clock.

All that time gets you is protection from replays.

RGDS
GARY
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Gary E. Miller Rellim 20340 Empire Blvd, Suite E-3, Bend, OR 97701
        gem () rellim com  Tel:+1(541)382-8588 Fax: +1(541)382-8676

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