8-bit message encrypted by gnupg appears as 7-bit after decryption?

[Jens]

this might be a silly question but my curiosity has not been satisfied after 
three days of continuous web searching so i hope somebody will humour me.

kmail encodes some of my utf-8 emails as base64. this happens when i dont 
allow 8bit and when i type arabic.

my question is this: after an outgoing message is encrypted with gnupg the 
body of the message appears as 7bit. meaning that when it arrives as the 
recipient he/she will have no way of knowing the original encoding after 
decryption.

does this never cause problems? how can the mua know whether the original 
email was 7bit, 8bit or base64?

i should also say that i have not had any problems but then again you rarely 
do when emailing yourself. i would just really like to know how the recipient 
knows what type of body he is dealing with.

thanks