May I draw your attention to the payment processor protocol BOP is about to roll out:
http://bitsofproof.com/?page_id=467Its goal is to facilitate payment settlement from customer to merchant without the technology provider (BOP) taking possession of the funds at any stage of the process. So it is not a payment processor.
The basic idea is simple:
1. Merchant provides a BIP32 master public key to BOP
2. Merchant asks BOP to create payment request
3. BOP draws a random sequence number it uses to derive the key out of the Merchant's Master Public
4. BOP presents customer the address of the key, that is actually an address of the Merchant.
5. Customer pays to the address
6. Merchant pays BOP the processing provision.
7. BOP reveals random sequence number it used
8. Merchant takes funds by creating private key for the sequence.
I am thankful for review and comments.
The solution will go limited beta on 10. August, and publicly available on 27. August with other tools at the Berlin Bitcoin Exchange.