Mathematical Fun with ErgoScript

Development Research and Development
15

Here is another example using a puzzle for addressing the same issue (DoS attacks). The idea works assuming that DEPTH is available.

{ 
  val x = OUTPUTS(0).R4[Coll[Byte]].get
  val y = OUTPUTS(0).R5[Coll[Byte]].get

  val commitmentBox = CONTEXT.dataInputs(0) // can also be input
  val commitmentX = commitmentBox.R4[Coll[Byte]].get
  val commitmentY = commitmentBox.R5[Coll[Byte]].get
  val commitmentOwnerPubKey = commitmentBox.R6[Coll[Byte]].get      

  val validCommitment = blakeb256(x) == commitmentX && 
                        blakeB256(y) == commitmentY

  val validReward = OUTPUTS(0).value = SELF.value && 
                    OUTPUTS(0).propositionBytes == commitmentOwnerPubKey

  // puzzle's goal is to find x != y such that sha256(x) == sha256(y)
  sha256(x) == sha256(y) && x != y && 
  validCommitment && 
  commitmentBox.DEPTH > 100 && 
  validReward
}

If DEPTH is not available (it isn’t yet unfortunately), there are other workarounds such as those suggested in the thread: “A trustless timestamping service for boxes”