feat: implement the dash analogue to BIP143

[panleone]

Issue being fixed or feature implemented

Implement the bip143 analogue for dash, see here for documenation (dashpay/dips#149).

What was done?

A new sigHashType SIGHASH_DIP0143 has been added and txs inputs with this new sigHashType are signed with the new signature hash algorithm specified in the document.
Feature is activated with an EHF hard fork and controlled with the script flag SCRIPT_ENABLE_DIP0143

How Has This Been Tested?

Many tests have been added:

• Verify that the new signature hash is generated correctly for a set of 100 transactions.
• Verify that script verification will accept new signatures only if there script flag SCRIPT_ENABLE_DIP0143 is set, and the signed input contains the sigHashType SIGHASH_DIP0143
• Verify that both signature (with new and old algorithm) can coexist in the same multisig transaction input and pass script verification, provided that the script flag SCRIPT_ENABLE_DIP0143 is set.
• Verify that the feature is rejected before activation.

Checklist:

Go over all the following points, and put an x in all the boxes that apply.

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated relevant unit/integration/functional/e2e tests
• I have made corresponding changes to the documentation
• I have assigned this pull request to a milestone (for repository code-owners and collaborators only)

[github-actions]

This pull request has conflicts, please rebase.

[UdjinM6]

Would be nice to have 7be17ee in a separate PR. Could maybe also introduce and use another helper like

bool HasExtraPayloadField() const
{
    return IsSpecialTxVersion() && nType != TRANSACTION_NORMAL;
}

while at it.

[UdjinM6]

pls check https://github.com/UdjinM6/dash/commits/pr5860/ branch for wip suggestions, specifically 84905a2

NOTE: I had to revert 0ef6ded and 160dc04 to make it work and also cf150bd to avoid merge conflicts in the future but the latter is optional I guess

[panleone]

pls check https://github.com/UdjinM6/dash/commits/pr5860/ branch for wip suggestions, specifically 84905a2

NOTE: I had to revert 0ef6ded and 160dc04 to make it work and also cf150bd to avoid merge conflicts in the future but the latter is optional I guess

My thoughts:

...
// Drop the signatures when SIGHASH_DIP0143 is not used, since there's no way for a signature to sign itself
    int nHashType = vchSig.empty() ? 0 : vchSig.back();
    if (nHashType & SIGHASH_DIP0143) {
        // Can't use using SIGHASH_DIP0143 hash type without SCRIPT_ENABLE_DIP0143 flag
        if ((flags & SCRIPT_ENABLE_DIP0143) == 0) {
            return set_error(serror, SCRIPT_ERR_SIG_FINDANDDELETE); //TODO
        }
    } else {
        int found = FindAndDelete(scriptCode, CScript() << vchSig);
        if (found > 0 && (flags & SCRIPT_VERIFY_CONST_SCRIPTCODE))
            return set_error(serror, SCRIPT_ERR_SIG_FINDANDDELETE);
    }
...

and

...
// With SCRIPT_VERIFY_CONST_SCRIPTCODE, OP_CODESEPARATOR is rejected even in an unexecuted branch
if (opcode == OP_CODESEPARATOR && /*sigversion == SigVersion::BASE && TODO*/ (flags & SCRIPT_VERIFY_CONST_SCRIPTCODE))
...

DIP0143 would have been a nice moment for imposing no OP_CODESEPARATOR and no signatures inside the script, but we already have a flag for that, SCRIPT_VERIFY_CONST_SCRIPTCODE. I think it is already enough and we don't need to re-impose those conditions with DIP0143, we would just overcomplicate it imo (or there is a particular reason for those additions that I am missing?).

[panleone]

pls check https://github.com/UdjinM6/dash/commits/pr5860/ branch for wip suggestions, specifically 84905a2

NOTE: I had to revert 0ef6ded and 160dc04 to make it work and also cf150bd to avoid merge conflicts in the future but the latter is optional I guess

My idea was that with the current implementation that we have DIP143 can be the very simple: when the right sighash_type is set serialize with the new algorithm , without changing anything else

[UdjinM6]

ok, so then smth like that 1eb9b4e on top I guess?

[panleone]

ok, so then smth like that 1eb9b4e on top I guess?

So that the overall effect is moving this check from CheckSig

if ((nHashType & SIGHASH_DIP0143) && sigversion != SigVersion::DIP0143){
    return false;
}

to EvalScript?

// Can't use using SIGHASH_DIP0143 hash type without SCRIPT_ENABLE_DIP0143 flag
if ((nHashType & SIGHASH_DIP0143) && (~flags & SCRIPT_ENABLE_DIP0143)) {
    return set_error(serror, SCRIPT_ERR_SIG_FINDANDDELETE); //TODO: introduce and use new script error

yes, I like it so we can even get rid of GetSigVersionFromFlags and probably of the whole enum SigVersion

[UdjinM6]

....
yes, I like it so we can even get rid of GetSigVersionFromFlags and probably of the whole enum SigVersion

not sure we can do that but let's see - we need tests :)

[panleone]

....
yes, I like it so we can even get rid of GetSigVersionFromFlags and probably of the whole enum SigVersion

not sure we can do that but let's see - we need tests :)

At the end I tried both methods and the one withSigVersion was much better, so I did not remove it.
So I reverted almost all refactor commits and the only left are:
437ef2f, which however can be removed to have less diff lines;
abad7f4, which removes SigVersion from EvalScript (because that variable was unused)

[UdjinM6]

Looks good so far! Pls see b100c66, d69d345 and 429db53 for some suggestions/fixes.

[panleone]

Looks good so far! Pls see b100c66, d69d345 and 429db53 for some suggestions/fixes.

review applied, with the addition of 00d60b9

[github-actions]

This pull request has conflicts, please rebase.