US Secret Service - the United States intelligence agency that protects current and former presidents and vice presidents and their immediate families and protects distinguished foreign visitors; detects and apprehends counterfeiters; suppresses forgery of government securities and documents.
It's  blessings not blessing.. The entire clause is ...to secure the  blessings of liberty to ourselves and our posterity....    The blessings of liberty refers to all of the benefits that are  afforded by having liberty.
Lyndon B. Johnson. We believe that all men have certain unalienable rights. Yet many Americans do not enjoy those rights. We believe that all men are entitled to the blessings of liberty. Yet millions are being deprived of those blessingsânot because of their own failures, but because of the color of their skin.