cloudy understanding of asymmetric cryptography

[Jim Hendrick]

Yup - you got it.

Symmetric encryption is *way* faster (that's a technical term :-) than
asymmetric.
Hence the slower version is used to exchange a random key that is then used
to handle the encryption/decryption of the data.
Algorithms are implementation dependent but it is common to use 3DES for the
symmetric. 

-----Original Message-----
From: gnupg-users-bounces at gnupg.org [mailto:gnupg-users-bounces at gnupg.org]
On Behalf Of Felipe Alvarez
Sent: Thursday, March 26, 2009 5:51 AM
To: gnupg-users
Subject: cloudy understanding of asymmetric cryptography

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Someone today shook my understanding of asymmetric ciphers.

_Bob performs symmetric encryption on message with_
_key "K" (generated randomly). He then encrypts "K" _
_with Alice's public key, and sends both the symetrically _
_encrypted message and asymmetrically encrypted key to Alice_

Is this what happens during most/some/all of public-key
communications? I had always thought that the message is encrypted
with public key, and decrypted with secret key. I was not aware that
key "K" was encrypted with public key, but message encrypted with
__symmetric_cipher__.

To help my understanding a little futher, if this does not always
occur, or does not usually occur, when does it occur (not occur)?
Using what ciphers (algorithms)?

I was unable to find adequate explanations online.

Thanks
Felipe

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.0.9 (GNU/Linux)

iEYEARECAAYFAknLT9sACgkQbm5xe/LPYKKywwCfZoz8b5XOW4EoSy+m6r/xIgli
rtcAn3Lb3cwzLL036BjOO5259rNhWFW5
=b2iF
-----END PGP SIGNATURE-----

_______________________________________________
Gnupg-users mailing list
Gnupg-users at gnupg.org
http://lists.gnupg.org/mailman/listinfo/gnupg-users