Example of signs that reveal divine authenticity and/or the conferring of Divine Authority are:

Exodus 4:17 (NIV)
17 But take this staff in your hand so you can perform miraculous signs with it."
Mark 16:17-18 (NIV)
17 And these signs will accompany those who believe: In my name they will drive out demons; they will speak in new tongues;
18 they will pick up snakes with their hands; and when they drink deadly poison, it will not hurt them at all; they will place their hands on sick people, and they will get well."

John 20:30 (NIV)
30 Jesus did many other miraculous signs in the presence of his disciples, which are not recorded in this book.

Acts 2:22 (NIV)
22 "Men of Israel, listen to this: Jesus of Nazareth was a man accredited by God to you by miracles, wonders and signs, which God did among you through him, as you yourselves know.

2 Corinthians 12:12 (NIV)
12 The things that mark an apostle--signs, wonders and miracles--were done among you with great perseverance.

2 Thessalonians 2:9-12 (NIV)
9 The coming of the lawless one will be in accordance with the work of Satan displayed in all kinds of counterfeit miracles, signs and wonders,
10 and in every sort of evil that deceives those who are perishing. They perish because they refused to love the truth and so be saved.
11 For this reason God sends them a powerful delusion so that they will believe the lie.
12 and so that all will be condemned who have not believed the truth but have delighted in wickedness.