Move util/message to common/signmessage so it is named more clearly, and
because the util library is not supposed to depend on other libraries besides
the crypto library. The signmessage functions use CKey, CPubKey, PKHash, and
DecodeDestination functions in the consensus and common libraries.
These files change infrequently, and not much header shuffling is required.
We don't add everything in src/util/ yet, because IWYU makes some
dubious suggestions, which I'm going to follow up with upstream.
And add unit test for it.
The purpose of using a preamble or "magic" text as part of signing and
verifying a message was not given when the code was repeated in a few
locations. Make a test showing how it is used to prevent inadvertently
signing a transaction.
The logic of signing a message was duplicated in 3 places:
src/qt/signverifymessagedialog.cpp
SignVerifyMessageDialog::on_signMessageButton_SM_clicked()
src/rpc/misc.cpp
signmessagewithprivkey()
src/wallet/rpcwallet.cpp
signmessage()
Move the logic into
src/util/message.cpp
MessageSign()
and call it from all the 3 places.
The logic of verifying a message was duplicated in 2 places:
src/qt/signverifymessagedialog.cpp
SignVerifyMessageDialog::on_verifyMessageButton_VM_clicked()
src/rpc/misc.cpp
verifymessage()
with the only difference being the result handling. Move the logic into
a dedicated
src/util/message.cpp
MessageVerify()
which returns a set of result codes, call it from the 2 places and just
handle the results differently in the callers.
