cloudy understanding of asymmetric cryptography

[Sascha Kiefer]

Yes, that is right.
Asymmetric encryption is a slow process. Encrypting the whole message would
take forever.
So, symmetric keys a quite small, that's why the described technique is
used.

Cheers,
Sascha

-----Original Message-----
From: gnupg-users-bounces at gnupg.org [mailto:gnupg-users-bounces at gnupg.org]
On Behalf Of Felipe Alvarez
Sent: Donnerstag, 26. März 2009 13:51
To: gnupg-users
Subject: cloudy understanding of asymmetric cryptography

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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

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