why gpg use SHA1 instead of pref???

[David Shaw]

On Thu, Mar 22, 2007 at 11:12:26AM +0000, redstar wrote:

> New: Symmetrically Encrypted and MDC Packet(tag 18)(70 bytes)
> 	Ver 1
> 	Encrypted data [sym alg is specified in pub-key encrypted session key]
> 		(plain text + MDC SHA1(20 bytes))
> 
> What I must do for using RIPEMD160 hash of encryption??? Its normal because
> encryption specifications requirements? Or its error of gpg?

The MDC is always SHA-1.  It is fixed as part of the protocol.

> Why he will use RSA encryption as other symmetric ciphers like CAST5, 3DES,
> BLOWFISH,, in prefs, and, RSA its not in prefs list?

The type of public-key encryption is defined by what type of key you
are encrypting to.  An RSA key means RSA encryption.  The symmetric
ciphers are not relevant to this question.

David