A few months ago there was a formal proposal for sighash_noinput, it’s a new
OPCode to be used in a technology called Eltoo. Eltoo is built on top of
Lightning to resolve problems with malicious channel closing, currently the way
to solve this is by giving all of the channel’s funds to the victim, but this,
in some cases, would require the entire channel’s history to be broadcast,
which isn’t remotely efficient.
Sighash_noinput brings a solution to this case, as mentioned in the Bitcoin
It removes any commitment to the output being spent from the signature
verification mechanism. This enables dynamic binding of transactions to
outputs, predicated solely on the compatibility of output scripts to input
But there was some controversy that this enables other malicious use cases if
it was used in anything other than LN and Segwit transactions, developer
Christian Decker mentioned that this is to be used only in very specific
scripts and should not be available for general wallets to sign with.