Quote

Now... the next puzzle costs around 150 $ to solve, so I'll stop for now.

What about additional 200k sats?

Code:

decoderawtransaction 02000000000102d36528b10fcb97b2449878da63c905360ea634613000dcd3734d6405b7ddc6680100000000fdffffff01280bc5682e0cbe78108912437ab583daa49a8fe66e995001a22a44aec2a3ab0600000000fdffffff0130e00300000000000451024e730247304402202c368f7b1bb7cd891f1a082773f6cca1219fb42ba6797c407ef34142debc685902204b8391fca6320f7eea32b77215f962fa019364c4f73272a73be0002f3a37eb89022102a2231b027ae19ac2f05fc8e2a63ed19494630c478732f0f5702d3495474d853f0000000000
{
"txid": "db94eefbfa2b53a46995a23cd7984935ef46bfb97ebd7cc611abb111ba3eafdf",
"hash": "6150f4cbe72257e524410e8d3fa0345a683273081de5723d938371c0d50a94c3",
"version": 2,
"size": 215,
"vsize": 133,
"weight": 530,
"locktime": 0,
"vin": [
{
"txid": "68c6ddb705644d73d3dc00306134a60e3605c963da789844b297cb0fb12865d3",
"vout": 1,
"scriptSig": {
"asm": "",
"hex": ""
},
"txinwitness": [
"304402202c368f7b1bb7cd891f1a082773f6cca1219fb42ba6797c407ef34142debc685902204b8391fca6320f7eea32b77215f962fa019364c4f73272a73be0002f3a37eb8902",
"02a2231b027ae19ac2f05fc8e2a63ed19494630c478732f0f5702d3495474d853f"
],
"sequence": 4294967293
},
{
"txid": "aba3c2ae442aa20150996ee68f9aa4da83b57a4312891078be0c2e68c50b2801",
"vout": 6,
"scriptSig": {
"asm": "",
"hex": ""
},
"sequence": 4294967293
}
],
"vout": [
{
"value": 0.00254000,
"n": 0,
"scriptPubKey": {
"asm": "1 29518",
"desc": "addr(bc1pfeessrawgf)#d6x2lh3c",
"hex": "51024e73",
"address": "bc1pfeessrawgf",
"type": "anchor"
}
}
]
}

Let's test transaction sponsorship. It is signed with SIGHASH_NONE, so it should be valid only within this specific puzzle. You can obviously change your output from bc1pfeessrawgf to anything else, because it is not signed.

I guess in that case, something else than nLockTime will be needed as a nonce, because unfortunately, it seems to be signed. However, by just using "OP_RETURN <anyData>" in some additional output, or using similar tricks, it should be possible to grind it. Also, as far as I know, nSequence should be unsigned, so it can be also used to grind it.

Also, I guess sponsors could potentially make their own transactions, if they would sign things with SIGHASH_SINGLE instead of SIGHASH_NONE, because then, they can pick a single address as a destination (but in this case they should be careful, to never sign out-of-bounds indexes, because it could be sweeped by anyone).