Keys To The Kingdom Meaning

(idiomatic) A resource, usually information or knowledge, the possession of which gives the possessor access to power.

Example: 1830, John Donald Carrick, Life of Sir William Wallace of Elderslie‎, p. 112:
  This fortress, from its strong position, was considered as one of the keys to the kingdom, and had belonged to the Earl of March, a disappointed candidate for the crown, who had now attached himself to the banner of England.
2002 April 8, InfoWorld‎, v. 24, no. 14, p. 28:
  The passwords they control are the keys to the kingdom, so what protections should be taken?
2008, Barack Obama (quoting Senator Robert Byrd), The Audacity of Hope: Thoughts on Reclaiming the American Dream‎, p. 119:
  Not many people bother to learn them these days. Everything is so rushed, so many demands on a senator's time. But these rules unlock the power of the Senate. They're the keys to the kingdom.