How to portray to a user the security of an input field?

I was just tasked by my boss to make a certain SSN field to appear more secure. We currently are masking the first 5 numbers but he wants a greater feel of security behind the input.

He was thinking a background with lines through it, but left most of the creative work to me. I am wondering:

  1. Is it bad UX to place a greater emphasis on the security of a field?
  2. Are there any examples I can view that can show such an idea?