message_signing::sigrec_decode panics for 0-length signatures #1005
Description
If an empty signature is passed to sigrec_decode, the function will panic at extracting rsig and rid.
Given sigrec_decode is private, this can either be fixed at recover_pk after zbase32 decoding the signature, by making sure its length is at least 2, or at sigrec_decode by checking the same.
Something on the lines of the following should do:
fn sigrec_decode(sig_rec: Vec<u8>) -> Result<RecoverableSignature, Error> {
if len(sig_rec) < 2 {
return Error::InvalidSignature;
}