I am new to mobile applications. I am basically from a web development platform. I am just playing around mobile frameworks like App Framework, LungoJS, Jquery Mobile, kendo etc
Please go through this link it will surely help you
http://www.androidhive.info/2012/01/android-login-and-registration-with-php-mysql-and-sqlite/
Webserver,cloud anything is good for restful service
for security purpose you can use POST parameter to send and recieve data or if you want more security then you can encrypt and decrypt data through secure algorithm