Right now, if you have a small piece of Monero, you can spend it with mixin 0. That way, you can collect a bunch of them without paying too high of fees.

RingCT will hide amounts, meaning it won't be apparent to the blockchain if something is dust. Will you be able to collect dust with 0 mixin if you reveal the amount (which would also allow the range proof to be omitted), or if you shrink the range of the range proof to prove that it is dust?


1 Answer 1


There were two main reasons outputs were called dust:

  • small outputs (typically well below 0.01, which is the fee per kB)

  • "complex looking" amounts, such 0.000013852456

The problem with the first type is that they might not "pay for themselves" in fees. Since fees in Monero are 0.01 per kB, if you use only small outputs, you may end up with a transaction with a sum of inputs that is below the needed fee.

The problem with the second type is that these weird non-denominated amounts are unlikely to have other outputs of the same amount on the blockchain, so they can't be spent in a mixin > 0 transaction.

With RingCT, the first problem stays. However, such outputs are much less likely to be created again. The second problem is gone altogether, since RingCT outputs can mix with any other RingCT output, regardless of their actual amount, since an external observer (including miners) cannot know its actual value.

Thus, the dust problem pretty much vanishes with RingCT. If you still have very small outputs that can't "pay for themselves", they can be spent alongside a larger input, and create a large "funny looking" rct output. But funny looking outputs are no more a problem with mixing, so it's all fine now.

After hard fork 5, when pre-rct transasctions are typically forbidden, they will still be allowed if spending unmmixable pre-rct inputs (ie, the rules that currently allow 0 mixin txes).

If you somehow end up with a very small rct output, then it will have to be spent alongside a larger one to meet the fee. There are no plans to "unmask" an rct output's amount. If you somehow end up with only very small rct outputs, then:

  • they're pretty much worthless anyway

  • you can wait for monero to become very expensive, in which case fees will go down

  • How does merging work? Aug 21, 2016 at 15:35
  • If you mean consolidating pre-rct outputs that cannot be mixed, pre-rct transactions will still be allowed for this after hard fork 5. If you mean merging rct outputs, it's a normal rct transaction with more inputs than outputs.
    – user36303
    Aug 21, 2016 at 15:45

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