Quote from: Rassah on December 12, 2013, 08:54:44 PM

That's what Blockchain.info does. You send from a single address, you give it an amount and a destination address, and it goes through 2+ CoinJoin steps, split up into random amounts from your source address, then after all the steps gets recombined into the amount you sent (minus transaction fee) into your destination address. Basically, it's as if your amount is exploded into random chunks, and then recombined into the same amount. Unless multiple steps involve multiple different coinjoiners, and much of what you get isn't tied to your own bitcoin at all, I'm not sure it's secure.

Assuming you use a single input of the exact size then it will be recombined into the same output value. But the client will deliberately select more inputs than necessary in order to make determining the input value more difficult. The server will also add multiple outputs of the same size as your inputs.

Even if you are restricting outputs to power of two sizes, as in the original coinjoin proposal, the same issue is still a problem. Address A sends 2 * 0.1 BTC + 1 * 1 BTC outputs then Address BTC receives 2 * 0.1 BTC + 1 * 1 BTC soon after it is easy to connect the dots.

Mixing in the background rather than on demand is probably the best way to solve this.