Interactive identification and digital signatures

An interactive identification scheme is a method for remotely (or locally) verifying an individual's identity. Interaction prevents the person who is doing the verifying from collecting information that could be used later to impersonate the individual. It also prevents anyone else from gaining such information. Interactive identification schemes have many potential applications — from providing more secure remote computer logins to providing more secure bank-card transactions. Such schemes can also be used to construct digital signatures, a way of signing an electronic document that makes the signature easy to check but difficult for an unauthorized person to forge. In this paper, we describe the general problems of identification and signatures, explain some shortcomings of current methods, and discuss how interactive identification schemes address them. We also describe an interactive identification scheme discovered at Sandia National Laboratories in which the security is based on the computational difficulty of solving two hard problems.