Subject: S2K and Tag 0x05 Q

From: Erron Criddle <[email-masked]>
Date: Wed, 06 Sep 2000 11:56:22 +0800

To all,

I've been looking at the S2K Usage (3.6.1) and, when using twofish as the 
symmetrical algorithm (in say a type 0x00 S2K Usage), what do you do if you 
want to use a 256 bit session key to encrypt the secret key? I'm assuming 
here that S2K will only allow a session key equal to the symmetrical 
algorithm block size...

If this is correct, what happens when 64 bit symmetrical algorithms are 
used...is the session key length limited to only 64 bits?

Or...

Do you decide what length of the S2K session key to use (in your program), 
then when the secret key needs to be extracted from the secret key-ring, 
just keep trying multiple session key lengths in block size multiples (as 
generated from the S2K specifier) until the checksum checks out OK?

It seems it would be a lot easier (maybe less secure?) if a session key 
length was specified somewhere.

Cheers.

Regards

Erron Criddle
Comasp Ltd.
Level 2, 45 Stirling Hwy
NEDLANDS  WA  6009
Australia

Fax: 08 9386 9473
Tel: 08 9386 9534

http://www.comasp.com
[email-masked]