使用jsp servlet和bouncy castle运行时异常

I have the following piece of servlet code (running on Apache Tomcat v7.0) that tries to get user input from a jsp page and subsequently try to AES encrypt it (implemented in my class AES_BC using bouncy castle). I'm instantiating my AES_BC class just for testing in the method myname(). The server comes up fine and I can supply some input, but when myname() is invoked in doGet, I get a run time exception. The code and exception are given below:I have the following piece of servlet code (run