This fixes block parsing on testnet; specifically, non-standard tx versions.
We hit a type bug in libwally (wallt_get_secp_context()) which I had to
work around for the moment, and the updated libsecp adds an optional hash
function arg to the ECDH function.
Fixes: #2563
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
It's more natural than using a zero-secret when something goes wrong.
Also note that the HSM will actually kill the connection if the ECDH
fails, which is fortunately statistically unlikely.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
To be safe, we should never memcmp secrets. We don't do this
currently outside tests, but we're about to.
The tests to prove this as constant time are the tricky bit.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
