How do I prove I am who I say I am? If I tell you my credit card number, username and password, or even my the name of my favorite pet, then in the future, you can use this information to pretend to be me! The trick is to prove I know some secret, such as my password, without revealing what it is. One approach is to prove knowledge of a solution to an NP-hard problem. This talk shows how we can confirm our identity by leveraging Groth-Sahai proofs-of-knowledge of a solution to a bilinear equation. Besides proving that we are who we say we are, we can also prove that other people have given us signed certificates. I can prove that I am over 21 and a student at Brown University without revealing who I am. I can even delegate my certificate, so my friends can prove that they know a student at Brown University over 21.