I only recently (a few days ago) started diving into pgp/gpg. It seems to me, and I could be wrong, that when someone encrypts a file/message to send to you, they need to use your public key to encrypt it. Your public key is generated from your private key. To have a key in the first place you need to run
This link should help though:
http://www.spywarewarrior.com/uiuc/g...com-4.htm#4-1d
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Edit
Also the output of your original command tells you that it was encrypted with ElGamal and gives you the key's ID.
If you know which keyserver (if any) the person used, you can use
Code:
gpg --keyserver keyserver.example.com --recv-key 98F004C9
To get their key. It may be that they encrypted it in such a way that you can decrypt it.