Is a secret key compromised by known cleartext?

Volker Gaibler volker.gaibler@urz.uni-heidelberg.de
Sat May 31 16:17:02 2003


On Sat, May 31, 2003 at 10:14:17AM +0200, tito@rumford.de wrote:
> If I got an email with a message in cleartext immediately 
> followed by the same message encrypted to my public key -- 
> would that change the status of my secret key (being secret) 
> abruptly to "being well known"?

No. Your public key is not secret and so is available to everybody (or
could be, if you decide to publish it). So everybody can choose a
cleartext and find the correspondent ciphertext. This is always possible
with public key crypto and so the algorithm always has to resist this kind
of attack. So finding lot's of plaintext-ciphertext pairs is no threat to
GnuPG.

Volker



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 Volker Gaibler                                 contact: 
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