bloomFilterData

Get some data that can be entered into a bloom filter to select transactions paying to this address.

Without knowing the exact contract, we cannot select the piece of data that is "most unique". This function selects a likely piece of data. In the worst case, this will return some data that matches more transactions than expected, resulting in a higher network load, rather than missing transactions. Note that if there IS no likely-unique piece of data, the function returns null. TODO: Note that we could be more accurate for common/popular script templates by writing specific code for that script template.

Data selection proceeds using the following algorithm: For script templates: Return the argsHash if it exists (hash of hidden args) otherwise return the first visible argument whose size is >= 20 bytes (possibly a cryptographic hash) otherwise return the template hash (if it exists) Otherwise give up and return null because there is nothing "interestingly unique" about this address that we can search on. Otherwise, return the first pushed piece of data >= 20 bytes