MutableTransactionSignatureCreator
(src/script/sign.cpp) seems to be where the sighash is created. There is one constructor
which takes a transaction (txToIn
), an input index (nInIn
), and amount, and a sighash type (eg. SIGHASH_ALL
).
https://github.com/bitcoin/bitcoin/blob/master/src/script/sign.cpp#L28
https://github.com/bitcoin/bitcoin/blob/master/src/script/interpreter.cpp#L1234