In the course of a friendly discussion with Dirk-Jan, I’ve been reading up on the miracles of digital cash.

And by digital cash, I do not mean lame stuff like Paypal, which is basically just an ordinary bank account to which you can send transfer orders. No, what I’m interested in is the real heavy stuff, whereby you have a digital wallet full of cryptographic “coins” which can be transfered from one party to another, without a single central entity keeping track of the contents of your wallet. Ideally, you want to be able to transfer such coins even off-line, without the central entity needing to be involved with every individual transfer.

There are a couple of basic problems with the idea of using bits as money, which any “crypto cash” system will need to find solutions for.
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