I am having the same problem that was originally posted here -- getting an incorrect false return on verifymessage().
$address = '1B8QAtcpBkL3jtfeMvfLiz8hnPi2U1KCyf';
$signature = 'HP1aJ5Pnx9WMrFOl9U76u5ZMkjnhqW+cxcIqAnGg1f6JhKX0jKChZnV94ewXnBNb0wA+3sIJdtszALPw8EbcXOc=';
$message = 'test';
$rpc->verifymessage($address, $signature, $message);
this returns
bool(false)
I'm using the api described here:
https://blockchain.info/api/json_rpc_apiMethod: verifymessage
Parameters: (String bitcoinaddress, String signature, String message)
Description: Verifies the signature and message matches the bitcoin address provided (See signmessage)
Returns: Boolean