OP_CHECKSIGADD got left behind!

[BlobMaster41]

OP_CHECKSIGADD got left behind!

We can not parse a transaction containing OP_CHECKSIGADD opcodes due to the following check:

if (!GetOp(it, opcode, item) || opcode > MAX_OPCODE || item.size() > MAX_SCRIPT_ELEMENT_SIZE) {
    return false;
}

[instagibbs]

Is this function ever used by something that invokes it in a tapscript context? If so, could you add a regression test?

[BlobMaster41]

Is this function ever used by something that invokes it in a tapscript context? If so, could you add a regression test?

Hey, yeah so if you try the following transaction, btcdeb wont be able to decode the script itself even if the script lead to an invalid transaction (on purpose, the script itself will be reverted after stack execution):

 ./btcdeb --verbose --debug=sighash,signing,segwit,taproot --txin=020000000001018743fd257bca71380c09e09359ba37cea9e760c974866ca8982a739cff16d3020000000000fdffffff02a086010000000000160014dc0d46077a225cbc9a844750f9bacb9ee5eed4f9c027090000000000225120647e7db279052199f234014f25608084aa3c4fe032e9a149f3d5bfc822af005a0614dc0d46077a225cbc9a844750f9bacb9ee5eed4f9200373626d317ae8788ce3280b491068610d840c23ecb64c14075bbb9f670af52c40c255ea59f8d453931d5efc4ce46b98a02e9c4c34ebbe13267b5151edf036d108289820ce4d961e391e2829600d011e65667dfe8e317e81fa5dff6897e6172b0e403ee42545b1b12cec59981724289b6265c7b1e02a1e798e21bf5d9c5e4015746b1752b8360ac56c1558bf5b514ba90c6c99ea0a715d290d70473f77dae64164e7fd6901200373626d317ae8788ce3280b491068610d840c23ecb64c14075bbb9f670af52cad20f6ff14388fd7cdcd229e8194d3ec1fe2ff54e18231464fc9f6e959c16a273f3aada9146be111472cff4df4c2052061c6c5929fbded8ebd88a91457d3bd43a330a6b08397e767de16fd355a882ef98874519c6303627369004c840203e68ee236fcc34933d493b305a6f0c7561259471d13ecd10dfe0e37633a7cbe02d38ea5b0ec9e22dbb36406baa3c5bbb02708e2bd94d49297ea6f3ebd26d18c77038244c130704f1e5068b0853914e8c36ed442f90b416660ba1cfa37e77c15ccc803b64a3280d026571035bcc88a4084e4c3e2142f3546f1c74de4cc471dbf6c588e510202004f4c5e1f8b080000000000020abb932fbe3b29b9a8c4b020d5a03827db283ba7b822393b23cdd220a3acd422ddc0ccc2a2a8a2c4b2b0a4d8ac24a3b422dbb8d4a432b7223535abdcd438bdd8a0222b27238f011fe0543f0000369e5a5b6400000067516841c10373626d317ae8788ce3280b491068610d840c23ecb64c14075bbb9f670af52ce7e4d593fcb72926eedbe0d1e311f41acd6f6ef161dcba081a75168ec4dcd37900000000 --tx=0200000000010151faed5859edb61095bb0a703d806ca6d5b346ec9cd7e62b55123dbe418e4fd20100000000ffffffff01801a060000000000225120647e7db279052199f234014f25608084aa3c4fe032e9a149f3d5bfc822af005a0440bdcd6f90e0c8041cc74fad9e6e1712c2a613b658570a09e874ba47973aac8edbd698644f39d26970e064f31258510d5cee122a874ddd27750aaf47aed67093f04043f695e4512b3842c6e9d494a6354dc454a398b54a3956d05774a2e09c340680d57717df4b495b7ba74035939bf6efa4c146f9e723aa91d9cb639fb10c5828558f002003e68ee236fcc34933d493b305a6f0c7561259471d13ecd10dfe0e37633a7cbe7cba20d38ea5b0ec9e22dbb36406baa3c5bbb02708e2bd94d49297ea6f3ebd26d18c777cba208244c130704f1e5068b0853914e8c36ed442f90b416660ba1cfa37e77c15ccc87cba20b64a3280d026571035bcc88a4084e4c3e2142f3546f1c74de4cc471dbf6c588e7cba529c41c150929b74c1a04954b78b4b6035e97a5e078a5a0f28ec96d547bfee9ace803ac025fc3ba6e23970f193823c72924d629199c63998b05d5fb3d43d8d5553068a1c00000000

After the change, the transaction can be executed without any problems.

Here is a valid version of the transaction. This transaction includes empty witnesses (so it works with OP_CHECKSIGADD). There is an other bug in btcdeb code. You can reproduce it via the following command (I did not fix it yet.):

 ./btcdeb --verbose --debug=sighash,signing,segwit,taproot --txin=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 --tx=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

Currently this valid transaction error with the following:
invalid script (witness stack last element)

The error is due to an invalid opcode being decoded: 32765. I would have to debug the code futher to find the cause of that bug.

As mentioned in BIP 342, this should be possible: https://en.bitcoin.it/wiki/BIP_0342

Potentially, we should add a check to verify that the transaction is taproot, if its not taproot, this opcode is not valid. This opcode is only usable for tapscript transactions.

Here the transaction on my local testnet:
https://mempool.opnet.org/tx/94546b3f6c338c2ab4c23c42f93828dfe23f9a686359564c4ba23d0dfcea3784

[nghuyenthevinh2000]

thanks man, this works like a charm, so far so good when I am using OP_CHECKSIGADD with tap