After doing more research into the secure authentication IC marketplace, I have decided to move away from my original plan of a secure element -- essentially a tamper resistant microcontroller that usually runs some kind of JavaCard operating system. The advantage of the secure element implementation was that current JavaCard apps like Visa Paypass could be integrated into the project but I decided that the secure elements were to secretive & hard to get ahold of & more of a headache than I think they are worth. Also they introduce extra layers of complexity that I believe increase the probability of a security issue.
What am I considering using now you might ask. Good question! Well, I wanted a small footprint, extremely low powered IC with anti-tamper mechanisms that is made to efficiently carry out Elliptic Curve Digital Signature Algorithm (ECDSA). Also two other vital features I was looking for were availability (no sense in finding the perfect chip if I can't get my hands on it) & a good & affordable dev kit. With these features in mind, my searching lead me to the Atmel ATECC108A. I think it is a perfect fit for the project & ordered the evaluation kit the other day. I should have some preliminary results up in about two weeks & if all goes well, I will get the dev kit (more expensive so wanted to use the much cheaper eval board first) & start building my first prototype!