What's the WORD DESCRIBES SOMEONE SIGNS a DOC. in front of another person to pro

Question:

What's the WORD DESCRIBES SOMEONE SIGNS a DOC. in front of another person to proof that is his real signature

So what is the word to describe this event? Like I need to find someone who is unrelated to me and then I sign a statement (for a certain pupose) in front of him/her in order to let him/her to proof that is my real signature. so I can bring this statement to another person.

What this event/action call?
What's the SOMEONE UNRELATED TO ME call?

Either a noun or verb is fine.Thanks very much

Best Answer - Chosen by Asker:

Notary Public. They have to be registered with the state in which the signing takes place. Most banks have a notary; you can also try UPS Store or Kinko's.