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3 total messages Started by Hart for CCCP chief in '88 Fri, 15 Jan 1988 04:47

#3947

Author: Hart for CCCP chief in '88
Date: Fri, 15 Jan 1988 04:47

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1014 bytes

I am currently looking into a public key encryption system for a bulletin board
network program. However, RSA is fairly CPU intensive, and the need for the
ultimate security is not great. It would be sufficient to merely be 'difficult'
for an average type. But the system really MUST be public key because any methodof passing keys makes the whole thing useless. So, is there any other function
that provides reasonable security, ie protection from casual passers-by, that
still has the RSA properties of being able to distribute a public key? This
would allow each user to generate their own key and send the public version by
ordinary mail.

-your help is appreciated-
dov

Re: Another question

#3963

Author: Stephen R. Tate
Date: Fri, 15 Jan 1988 17:20

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1303 bytes

In article <8801150155.AA11615@decwrl.dec.com> kruger@16bits.dec.com (Hart for CCCP chief in '88) writes:
>I am currently looking into a public key encryption system for a bulletin board
>network program. However, RSA is fairly CPU intensive, and the need for the
>ultimate security is not great. It would be sufficient to merely be 'difficult'
>for an average type. But the system really MUST be public key because any method
>of passing keys makes the whole thing useless.

Why no just use shorter keys in an RSA scheme?  You've got a good trade-off
here between complexity of encryption and security -- if you want something
simpler and can live with less security, just make the keys shorter.  Nothing
says you have to use 100 digit keys.....

-- 
Steve Tate			UUCP: ..!{ihnp4,decvax}!duke!srt
				CSNET: srt@duke
				ARPA:  srt@cs.duke.edu
"There ain't nothin' in the world that a T-Bone Shuffle won't cure."

Re: Another question

#3950

Author: Peter Monta
Date: Sat, 16 Jan 1988 00:22

19 lines
1399 bytes

> > I am currently looking into a public key encryption system for a bulletin
> > board network program. However, RSA is fairly CPU intensive ...
>
> Why not just use shorter keys in an RSA scheme?

This is certainly an option, but it seems to me that any RSA system with
keys short enough to compete on a microcomputer with, say, DES in software,
would be trivial to crack (by factoring the key).

However, it might be reasonable to use RSA (or other public-key system) for
key distribution: use the recipient's public key to encrypt a DES key, say,
then send RSA-encrypted key and DES-encrypted message.  This would use the
public-key system on only a very short message, bootstrapping to a
conventional, faster cryptosystem.

Peter Monta
uucp:  ...!bbn!husc6!bloom-beacon!mit-amt!mit-caf!monta
arpa:  monta@caf.mit.edu

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