Re: Cypherpunk Certification Authority
At 11:20 AM 11/25/95 -0800, you wrote:
At 01:53 AM 11/26/95 -0800, anonymous-remailer@shell.portal.com wrote:
You'd rather sign before encryption?? Doesn't that give you "known plain-text" to attack?
The signature is not known unless the whole message being signed is known.
Signatures often have known, or easily guessed, plaintext in them, like the signer's name or ID number, or various header fields such as X.509's equivalent to ----- BEGIN PGP ....
And any encryption scheme that is vulnerable to known plaintext attack where only a part of the message is known, is worthless anyway.
DES isn't worthless. It's a bit weak, but not worthless. #-- # Thanks; Bill # Bill Stewart, Freelance Information Architect, stewarts@ix.netcom.com # Phone +1-510-247-0663 Pager/Voicemail 1-408-787-1281
Hello, On Mon, 27 Nov 1995, Bill Stewart wrote:
Signatures often have known, or easily guessed, plaintext in them, like the signer's name or ID number, or various header fields such as X.509's equivalent to ----- BEGIN PGP ....
If the signature is padded with random junk on the end, then it makes it harder to do a known text attack. There was a message a few days ago by Anderson and someone else (in England) that dealt with weaknesses in some encryption protocols. It was good to read.
DES isn't worthless. It's a bit weak, but not worthless.
Even though he didn't have proof Bruce Schneier stated in "Applied Cryptography 2nd Ed" that the NSA might have a machine that can crack DES in 15 mins, and maybe as low as 3-5, as one was built and sold. The book can explain it more, as I am doing this from memory. Take care and have fun. ========================================================================== James Black (Comp Sci/Comp Eng sophomore) e-mail: black@eng.usf.edu http://www.eng.usf.edu/~black/index.html **************************************************************************
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