Choosing the Hash and cyphering algorithm

Atom 'Smasher' atom at suspicious.org
Tue Dec 21 06:31:47 CET 2004


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On Mon, 20 Dec 2004 npellegr at numericable.fr wrote:

> Just an issue I hope somebody could help me with :
>
> 1) How could I specify (whether it's possible!) what hash algorithm: 
> MD5, SHA-1 TIGER ... (Ok i'm joking for MD5 !!) I want to use for 
> signing ?
===================

take tiger off of your list, it's no longer part of rfc2440.

"--personal-digest-preferences" will let you specify your order of 
preference for hash. note that if you (hypothetically) make md5 your most 
preferred hash and encrypt a message to someone who does not list md5 in 
their key's preferences, it will be skipped.

in a (1.4) config file:
 	personal-digest-preferences MD5 SHA-1 RIPEMD160


> 2) The same for symmetric cyphering, is possible to specify i need to 
> use DES or AES or 3-DES ?
======================

same thing, this time with "--personal-cipher-preferences".

using my key as an example, my preferred ciphers are:
 	Twofish with 256-bit key(sym 10)
 	Blowfish(sym 4)
 	CAST5(sym 3)
 	Triple-DES(sym 2)

if a (1.4) config file contains:
 	personal-cipher-preferences AES AES192 AES256 BLOWFISH CAST5

and you encrypt a message to me, blowfish would be used. it's the first 
match between our preferences.


> 3) Is it possible (like it's likely done during the signing step) to 
> cypher something using my RSA secret key ?
======================

gpg -ear 0x12345678!

where "0x12345678" is the subkey you want to specify. just add the bang 
(!) at the end and you can specify a particular subkey.


- -- 
         ...atom

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