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.
But Moses has doubts. How does he know that this is really God and how will he prove God's identity when he talks to the Hebrews? In Exodus 4:1-8 Moses answered, "What if they do not believe me or listen to me and say, 'The LORD did not appear to you'?" Then the LORD said to him, "What is that in your hand? A staff," he replied. The LORD said, "Throw it on the ground." Moses threw it on the ground and it became a snake, and he ran from it. 4 Then the LORD said to him, "Reach out your hand and take it by the tail." So Moses reached out and took hold of the snake and it turned back into a staff in his hand. 5 "This," said the LORD, "is so that they may believe that the LORD, the God of their fathers—the God of Abraham, the God of Isaac and the God of Jacob—has appeared to you."
A person can authenticate their identity to varying levels of assurance by presenting something they are, something they have, or something they know. The assurance level can be raised by using multiple methods or using the same method with different information multiple times. In the example with God, Moses, and the Hebrews God uses something he has to prove his identity, His power. In fact, God uses it three times and gives Moses three tokens--the ability to use the staff, water and his cloak to perform miracles--to use when he asserts God's identity to the Hebrews.
Something tells me there are more principles that I could pull out of the Bible around these issues.