Zero-Fee PrivateSends observed in the network. Have I Found a Hidden Feature?? Can someone explain??

[cazlutz]

I have found multiple instances where there were 0 DASH/kB for private send transactions. Is this a hidden feature? I thought masternodes charged a mandatory fee of 0.0125 DASH per mixing round, correct?

I observed PrivateSends in multiple blocks with the 1000DASH denomination where there were no private send fees. Block numbers:

85845
88139
201543
248366
414642
642893
643358
686865
689407

Thoughts?

 

[thephez]

I have found multiple instances where there were 0 DASH/kB for private send transactions. Is this a hidden feature? I thought masternodes charged a mandatory fee of 0.0125 DASH per mixing round, correct?

I observed PrivateSends in multiple blocks with the 1000DASH denomination where there were no private send fees. Block numbers:

85845
88139
201543
248366
414642
642893
643358
686865
689407

Thoughts?

The only PrivateSend denominations are 10, 1, 0.1, and 0.01 - https://github.com/dashpay/dash/blob/master/src/privatesend.cpp#L154-#L176. I looked at a couple of the blocks mentioned. They are simply 0-fee transactions with the same number of outputs and same value as the inputs. You could construct a transaction like this for any value you wanted using the RPC commands. Actually, you could do this with Bitcoin too.

Also, no mixing transactions have a fee because the fees are handled separately to maximize privacy. You can see a (presumed) PrivateSend mix transaction here. That assumption is based on the value of the inputs/outputs (they aren't actually exactly 10, 1, 0.1, or 0.01 but have a small bit in addition to help distinguish them from normal transactions).