I'm specialized in applied crypto, and a moderator on crypto.SE. My main expertise is / was smart card development, specifically Java Card development where I was member of the JCF. I've programmed up to and including EC based anonymous identity and attribute based crypto on a smart card and designed / created implementations of PKCS#11, TLS, WebSecurity, X.509 and much much more. I've answered more than 10% of all crypto questions on SO and helped to secure a score of others.
Beware of copy / paste crypto on StackOverflow. It is not a good idea to rely on copy / paste security; really, you have to know what you are doing. Do a course on e.g. Coursera first.