I managed to write down what I conceptually want to create. You can read the description here.

Notice the difference with the Ripple, in the use of a shared Bitcoin wallet to back IOUs.

I don't know whether this can be implemented on the Ripple network. I suspect it is not possible: if I am correct, there are only a limited number of message types in the Ripple protocol, and some of the things I want to do probably don't fit in these message types.

After writing this, I suspect that it might be possible to add arbitrary-currency transactions to my concept, while keeping the shared wallets based on Bitcoin. However, that is something that still needs to be investigated, and it is almost certainly going to cause some trouble and require important design choices.

My next goals are:

• have a detailed network protocol specification
• have a architectural diagram for the first implementation

But first, I am going to make some quick prototypes, to find out what works and what doesn't.

In the future, you can expect me to release a prototype with a web interface, that works with testnet. Then I want to invite the white-hat hackers in this community to tell me what's wrong with it.

In fact, if you already spot some problems in the conceptual description of my design, please tell me ASAP.