When you do get without a type you will default to Word as the input filter. You should really never use $input->get()
the way you are, use something like $input->getString()
or $input->getInt()
and so on. That will give you the correct input filtering. Read the JInput class docblocks for more details.
And in the meantime don't hard code your private key like that, it's not maintainable, what if you need to generate a new key?