Rijndael

[Werner Koch]

On Sun, 7 Jan 2001, Peter Schuller wrote:

> I'm just wondering; in what manner is Rijndael supported? I see no mention

Rijndael (aka AES) is fully supported.  Because it is a symmetric
cipher you won't see it in the key generation menu.  However,
Rijndael is listed with top priority in the preferences for
symmetric algorithms.  

> I may be confused about this, but the way I understand it one algorithm is
> used to encrypt/decrypt actual content, and one algorithm is used to encrypt
> the private key with a passphase.

The default algorithm used to protect the passphrase is CAST5.
The default algorithm used for symmetric only encryption (gpg -c) is
also CAST5 - you change this with the option --cipher-algo RIJNDAEL.
If you use --s2k-cipher-algo RIJNDAEL both, passphrase protection
and symmetric only encryption, uses RIJNDAEL.  

Unless you use --cipher-algo, the symmetric algorithm used for
normal public key encryption is calculated by looking at the
preferences of all recipients keys.

> Also, does Rijndael support arbitrary key sizes? I've seen horrifying
> statements that it supports "256 bit keys" (and similar) which would
> indicate that it does *not*.

AES is defined to allow 3 key seizes: 128, 192, 256 bit.  I don't
suggest to use 192 or 256 because this is just overkill for almost
all applications of GnuPG.

  Werner



-- 
Werner Koch                                              <wk@gnupg.org>
GNU Privacy Guard                                (http://www.gnupg.org)
Free Software Foundation Europe              (http://www.fsfeurope.org)
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