Witness construction help

[i5hi]

Currently when constructing a Witness, we have to construct it as a Vec<Vec> in elements

FWIU bitcoin::blockdata::witness::Witness struct abstracts aspects of the BIP141 spec, which one would have to do manually with the elements crate.

I have been running into issues while attempting to solve the same script in Elements, as I have in Bitcoin.

In bitcoin, the working witness construction is as follows:

        let mut witness = Witness::new();
        witness.push_bitcoin_signature(&signature.serialize_der(), hash_type);
        witness.push(preimage.bytes.unwrap());
        witness.push(self.swap_script.to_script().unwrap().as_bytes());

In elements, I am attempting the following:

        let mut script_witness: Vec<Vec<u8>> = vec![vec![]];
        script_witness.push(sig);
        script_witness.push(preimage.bytes.unwrap().to_vec());
        script_witness.push(self.swap_script.to_script().as_bytes().to_vec());

This fails with Signature must be zero for failed CHECK(MULTI)SIG operation

This could be an error with how I have contructed the Transaction; although I think I have got that right. Even if I have not, is the above Witness construction correct?

[i5hi]

If adding Witness to the library would be as straightforward as copying and adapting existing code from rust-bitcoin, I would love to attempt it.

[i5hi]

Updated the initialization since its adding an empty array at the start.

let mut script_witness: Vec<Vec<u8>> = vec![sig];
// script_witness.push(sig);
script_witness.push(preimage.bytes.unwrap().to_vec());
script_witness.push(self.swap_script.to_script().as_bytes().to_vec());

Still get the same error.

[i5hi]

Yes, the error was in my construction of the SigHash Message. I was using the output value instead of the previous_output value.

I got it to work by constructing a Witness and then using to_vec()