I am currently reviewing a computer science conference paper. The authors in the paper mention that the following is a non-standard script.
OP_DUP OP_HASH160 OP_0 OP_EQUALVERIFY OP_CHECKSIG
But when I checked the transaction on the explorer, its output script has NULL_DATA https://btc.com/btc/transaction/03acfae47d1e0b7674f1193237099d1553d3d8a93ecc85c18c4bec37544fe386
Which is the above two is true? Thank you
This script is almost exactly the same as the standard Pay-To-Public-Key-Hash (P2PKH) script, except instead of pushing the hash onto the stack it pushes an empty vector.
As a reminder, a P2PKH script locks an output with the hash of a public key. To spend this output one must provide both the public key and a signature generated from its corresponding private key. Since the hash function always produces a 20-byte hash and never an empty vector, there is no public key to satisfy this script, making the output forever unspendable.
Why this output exists I can't tell you, but a bitcointalk.org message mentions there are 23 of these. Most likely it's the result of a software bug.
NULL_DATA is probably just that specific blockchain explorer's label used for non-standard outputs. mempool.space marks this as UNKNOWN.
