PEM question

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2 total messages Started by Robert Ames Sun, 04 Oct 1992 07:53

#1311

Author: Robert Ames
Date: Sun, 04 Oct 1992 07:53

10 lines
747 bytes

A number of people have replied to my question about the PEM protocol,
pointing out that even if the private key involved in one message
exchange were to be discovered, this would only have the effect of a
"known plaintext attack" on the RSA encryption used to exchange the
keys.  In other words, the sender's private RSA would remain secure.

Thanks for the response.

-- 
Robert Ames mirage1@gpu.utcs.utoronto.ca  P.O. Box 724, Station 'A', Toronto

Re: PEM question

#1018

Author: Joseph F. Hull
Date: Wed, 07 Oct 1992 23:02

28 lines
1911 bytes

Bob, 
Your choice of words in this article runs a serious chance of confusing 
the issue.

In article <BvL79M.8on@gpu.utcs.utoronto.ca>, 
mirage1@gpu.utcs.utoronto.ca (Robert Ames) writes:
|> A number of people have replied to my question about the PEM protocol,
|> pointing out that even if the private key involved in one message
                                 ^^^^^^^^^^^   
|> exchange were to be discovered, this would only have the effect of a
|> "known plaintext attack" on the RSA encryption used to exchange the
|> keys.  In other words, the sender's private RSA would remain secure.
                                       ^^^^^^^^^^^
What you call a "private key" above should be called a "single message key"
to avoid any chance of someone else confusing it with the "private key"
part of a public key encryption system, what you call "private RSA" above.

A large part of PGP's strength is due to the fact that very limited amounts of
information are ever directly protected by a single key, i.e., only one
message is ever protected by the "single message key" and only the (very small
amount of information of the) "single message keys" transferred between
changes of "public key / private key" pairs is protected by those keys.

-- 
	   _   _
    /_    / ) / ) Jeff Hull          jhull@den.mmc.com
   //_) -/- -/-   1544 S. Vaughn Cir
/_/ \_/ /   /	  Aurora, CO 80012   303-977-1061

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