Proving that a box is created by a particular PK
The only thing that needs to be done is to issue a token in a transaction and put it in the output in which you want to prove you have created, also put the INPUTS(0).bytes in one of its registers!
Obviously, the token id is equal to the id of the first input of the transaction, hence a contract can make sure that the box is created by a particular person (in this case “9gAKe…”) by:
{
val prev = INPUTS(0).R4[Coll[Byte]].get
sigmaProp(INPUTS(0).tokens(0).id == blake2b256(prev) &&
bytesToBox(prev).propositionBytes == PK("9gAKeRu1W4Dh6adWXnnYmfqjCTnxnSMtym2LPPMPErCkusCd6F3").propBytes)
}
bytesToBox is not a real function, please let me know the correct way to get Box from its serialized bytes (box.bytes).
The above does not necessarily make sure that INPUTS(0) is actually created by “9gAKe…” but makes sure that “9gAKe…” has participated in the chain of transactions leading to here!
The very use case that came to my mind and made me think about such a thing is for a particular person to give permission for some operation by following this design pattern (for example giving permission for spending some box to the assembler service), hence outsourcing it.
In other words, in a well-designed system in which it doesn’t allow the token to get in the hands of an attacker, we can assume that the person is giving permission for some predefined operation because no one but her could have created such a box!