Traditional cryptography relies on unproven complexity assumptions that certain problems, such as integer factorization, are computationally hard. However, advances in algorithms and computing technology may render current cryptosystems insecure, and lead to decryption of past secret messages.
In this talk, I will present cryptographic protocols in a new setting, where provable everlasting security can be achieved without any complexity assumption. My first result, in joint work with Michael Rabin, will describe an efficient encryption and authentication scheme that is provably secure against strong adaptive attacks, by an adversary who is computationally unbounded. Our encryption scheme further enjoys the surprising property that even if the secret key is captured by the adversary after the transmission of the ciphertext, the secrecy of the message is assured.
Oblivious transfer is a cryptographic protocol that can serve as a basic primitive for all of cryptography. I shall present an implementation of oblivious transfer in the same setting, which is again provably secure without complexity assumption.