Decrypt Message

I am writing a small Java Web application that can decrypt the AS2 message.

I created and sent the message from the medndelson as2 1.1.

The message is signed and encrypted using certificates.p12 that is provided by the medndelson.

My question is How can decrypte the message?

Can I use the same certificate to decrypte the message?

From the log file, I know that the messages is singed with the algorithm 3DES, using keystore alias "KEY1".

And the message is encrypted with the algorithm "SHA-1", using keystore alias "KEY2".

I assume that I should decrypted the message using KEY2 first?

Please advise.

Thanks.