Conversion Functions for Symmetric Key Ciphers

Date Added: Jan 2011
Format: PDF

As a general design criterion, a symmetric key cipher should not be closed under functional composition due to the implications on the security of the cipher. However, there are scenarios in which this property is desirable and can be obtained without reducing the security of a cipher by increasing the computational workload of the cipher. The authors expand the idea of a symmetric key cipher being closed under functional composition to a more general scenario where there exists a function that converts the ciphertext resulting from encryption under a specific key to the ciphertext corresponding to encryption with another key.