When sending Monero the confidential transaction feature of RingCT hides thetransaction amount. Is there a privacy leak with the current xmr.to setup that weakens that claim?

Assume an online electronics vendor is selling televisions for 0.092 Bitcoin each. Monero users would send that equivalent in Monero to xmr.to which would forward 0.092 BTC immediately (orders up to 0.1 BTC will be sent out instantly) to the electronics vendor. Depending on the block in which the Monero was sent, there may only be a small number of Monero transactions, one of which we know was for exactly the Monero equivalent of 0.092 Bitcoin.

Is the above analysis correct? If so, could the problem be mitigated by modifying xmr.to so that it could send to multiple Bitcoin addresses at once and/or also make (partial) Monero refund transactions? Transaction amounts of the incoming Monero payments would appear harder to match with < 0.1 Bitcoin outgoing transactions with this modification.

Let's say it is possible to guess the exact Monero transaction on the blockchain that resulted in the corresponding Bitcoin transaction.

That would not constitute a significant privacy leak. No one can know your Monero wallet address or even which outputs you were actually spending.

Your analysis is correct, however knowing that the transaction is one of the five transactions (in average) of a block will not help to identify your address as it will be one of the 5*7=35 addresses of the lot used as ring signatures.

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