Family secrets

Abstract

We consider the possibility of secure communications over an insecure channel when the two agents have no verifiable public keys, no shared cryptographic information, and no trusted third party to assist them. We investigate two scenarios. In the first, the agents are biologically related, and use biological data to construct a shared key; the possibility of using DNA data, shared between the two parties but not readily available to others, is considered. The second concerns unrelated parties who have some printed material, such as a photograph, in common; we explore the possibility of scanning this material at both ends and constructing a secret key from the shared information. In each case, the two parties can convert their information into approximately equal sequences of bits. We borrow results from coding theory to show how these approximate sequences can be turned into exactly equal shared keys without compromising security in the process. © 2005 by International Federation for Information Processing.