I've been doing a lot of thinking about identity establishment and authentication in the last few years. Today I was reading Exodus--the story of Moses and the burning bush--when I realized that it served as a good example of the issues and provides a number of techniques for dealing with them.
In Exodus God establishes His identity with Moses by appearing to him in a burning bush. God gives Moses a charge to free the Hebrews from Egypt in His name. When Moses asks how he should establish God's identity when he returns to the Hebrews God says, in Exodus 3:13-16, "Say to the Israelites, 'The LORD, the God of your fathers—the God of Abraham, the God of Isaac and the God of Jacob—has sent me to you.' This is my name forever, the name by which I am to be remembered from generation to generation."
God uses a web of trust (three people) to assert His identity to the Hebrews. The Hebrews trust their fore-fathers--Abraham, Isaac, and Jacob--they know that they all worshiped the same God. In this instance Moses is to go to them and say that that same God has sent him.