Encryption and signing of a data file

[Gries, Jasmin]

Dear GnuPG-users,

as I want to test a kind of electronic voting by using GnuPG I tried first
to encrypt a data file and then to sign it (exactly in this reverse order),
but I doubt whether this is possible at all? 
For a better understanding enclosed the modell of the planned voting.

Participants:
Voters
2 trustees (trustee 1+trustee 2)

Implementation: 
1) Voters encrypt their vote with the public key of trustee 2 
2) Voters sign their encrypted vote 
3) Voters send their encrypted vote to trustee 1
4) trustee 1 will check, if the voter is entitled to vote and if he has
casted only 1 vote 
5) if this is ok, then trustee 1 will remove the signature 
6) trustee 1 signs the encrypted vote 
7) trustee 1 sends encrypted and signed vote to trustee 2 
8) trustee 2 will check, if the encrypted vote is transmitted lawfully 
9) trustee 2 decrypts the vote and compiles statistics on the vote 
trustee 1 knows the voters, but not their vote
trustee 2 knows the vote, but not the voters 
If the ballot is appealed
- trustee 1 can definitely prove which persons have voted
- trustee 2 can definitely prove which votes he has received freom trustee 1

Could anybody tell me whether I can do this kind of simultaneously voting
and singing with GnuPG?
Could I alternatively do this kind of voting by using mails instead of a
data file? Here I had the same problems.

Thanks for your help!!!

Jasmin