Information-theoretic Key Encapsulation and its Application to Secure Communication
share
A hybrid encryption scheme is a public key encryption system that consists of a public-key part called the key encapsulation mechanism (KEM), and a (symmetric) secret-key part called data encapsulation mechanism (DEM): the public-key part is used to generate a shared secret key between the two parties, and the symmetric key part is used to encrypt the message. Hybrid encryption schemes are widely used for secure communication over the Internet. In this paper, we initiate the study of hybrid encryption in preprocessing model which assumes access to initial correlated variables by all the parties (including the eavesdropper). We define information theoretic KEM (iKEM) that together with a (computationally) secure DEM results in a hybrid encryption scheme in preprocessing model. We define security of each building block and prove a composition theorem that guarantees security of the final encryption system. We showthat iKEM can be realized by a one-message SKA (OW-SKA)protocol with an extended security definition. Using a OW-SKA that satisfies this extended definition of security effectively allows the secret key that is generated by the OW-SKA to be used with symmetric key encryption system such as AES in counter mode. We discuss our results and future work including providing stronger security for the final encryption, and using information theoretic DEM to construct information theoretic encryption systems.
READ FULL TEXT