From: frantz@netcom.com (Bill Frantz)
Date: Wed, 31 Jan 1996 07:18:26 +0800
To: Alexandra Griffin <cypherpunks@toad.com
Subject: Re: PPP link encryption?
Message-ID: <199601301931.LAA02253@netcom6.netcom.com>
MIME-Version: 1.0
Content-Type: text/plain


At  6:36 AM 1/30/96 -0500, Alexandra Griffin wrote:
>Is there any software out there on the net for doing real-time,
>transparent encryption of a PPP link?
>...
>Finally, could someone make a ballpark estimate as to the amount of
>additional latency that would be added?

Ballpark estimate:  If the encryptor receives a complete packet before
encrypting and forwarding it then there would be an additional
packetSize/byteRate + encryptionTime seconds added to the packet's transit
time.

If the encryptor encrypts "on the fly", passing the bits of a packet as
their are received, then it would add almost no latency.  However, the
encryption algorithms would be limited to stream cyphers, which have
security and error recovery implications.  See "Applied Cryptography" for
details.


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Bill Frantz                   Periwinkle  --  Computer Consulting
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