I was reading this from the Bitcoin wiki (https://en.bitcoin.it/wiki/From_address). I understand the concept of UTXOs and that any input to a transaction is an output from a previous transaction. I also have a rough understanding of how ScriptSig and ScriptPubKey interact. The article mentions “advanced transactions will probably defeat most block explorers” and gives examples of some transactions one of them being:
54fabd73f1d20c980a0686bf0035078e07f69c58437e4d586fb29aa0bee9814f
When looking at this transaction in say blockchain.com the input is marked as “unknown” and when looking at the JSON for the transaction the input address is “null”
"inputs": [
{
"coinbase": false,
"txid": "a60143eb3f8d3cd1f42cca874f35736186d67c488efd3c1b7214bbd74b310e0c",
"output": 0,
"sigscript": "483045022100d92e4b61452d91a473a43cde4b469a472467c0ba0cbd5ebba0834e4f4762810402204802b76b7783db57ac1f61d2992799810e173e91055938750815b6d8a675902e014f",
"sequence": 4294967295,
"pkscript": "76009f69905160a56b210378d430274f8c5ec1321338151e9f27f4c676a008bdf8638d07c0b6be9ab35c71ad6c",
"value": 9000000,
"address": null,
"witness": []
}
],
I then looked at the input TXID a60143eb3f8d3cd1f42cca874f35736186d67c488efd3c1b7214bbd74b310e0c and the output address is also “null”
"outputs": [
{
"address": null,
"pkscript": "76009f69905160a56b210378d430274f8c5ec1321338151e9f27f4c676a008bdf8638d07c0b6be9ab35c71ad6c",
"value": 9000000,
"spent": true,
"spender": {
"txid": "54fabd73f1d20c980a0686bf0035078e07f69c58437e4d586fb29aa0bee9814f",
"input": 0
}
}
]
Can someone explain for me what is going on here? And how one goes about creating these “advanced transactions” that apparently defeat block explorers that the article mentions (as in what makes them special to break block explorers?)
I have seen the question at Can PUSHDATA/OP_RETURN be used to break a trail of transactions permanently? and the answer talking about the “nonstandard” vout type but I don’t understand what this means.
EDIT: I have seen “null” addresses in the context of OP_RETURN as outputs but my understanding is that those can’t ever be spent so I don’t understand how they are used as inputs.
