I was 'secure in the belief/knowledge' that I had done all I could. [=I felt confident because I believed/knew that I had done all I could]
They are 'financially secure'. [=they have enough money to live on; they do not have to worry about money]
You can access your bank account online using a 'secure' [='secret'] password.
(..) There's something else you have to see. MAN : Hard wall. OLSEN: Get what we came for, Barbarosa. The clock's ticking. Spread out, secure the perimeter. I got a big gap over here. JOHN: Why didn't we know about this? BARBAROSA: Sir, I think this is what Command's looking for. (..)2009 Terminator Salvation