On Tue, Mar 1, 2011 at 9:34 AM, <lists.gn...@mephisto.fastmail.net> wrote: > On Tue, Mar 01, 2011 at 01:13:16PM +0000 Also sprach Guy Halford-Thompson: >> >> Not GPG specific, but I was wondering if someone could point me in the >> direction of some resources that explain why we use different keys to >> sign and encrypt (for cases where the same key _could_ do both e.g. >> RSA). > > This may not be the whole story, but I did manage to find this: > > http://www.di-mgt.com.au/rsa_alg.html#weaknesses >
The weaknesses documented there do not seem to apply to OpenPGP (and hence GnuPG). One, messages are not actually encrypted with RSA; a symmetric algorithm is used to encrypt messages and the key to that encryption is encrypted with RSA. I believe that GnuPG uses a larger encryption exponent, reducing the threat posed by the Chinese Remainder Theorem. The threat of the "same key" on that page only applies where the RSA encryption was done to the plain text directly. Likewise, OpenPGP signing is done on a hash of the plain text. (Again, not on the plain text directly.) David -- David Tomaschik, RHCE, LPIC-1 System Administrator/Open Source Advocate OpenPGP: 0x5DEA789B http://systemoverlord.com da...@systemoverlord.com _______________________________________________ Gnupg-users mailing list Gnupg-users@gnupg.org http://lists.gnupg.org/mailman/listinfo/gnupg-users