Designing stream ciphers with scalable data-widths: a case study with HC-128
For optimal utilization of the resources, a stream cipher running on a \(w\)-bit machine should ideally produce \(w\) bits in every round of keystream generation. With increasing data-widths of processors, scalability of stream ciphers is a pertinent issue which is often addressed with ad hoc cipher-specific designs. In this paper, we propose a generic framework for designing stream ciphers with scalable data-widths by combining multiple instances of a single stream cipher following certain principles. We demonstrate using a case study on the fastest software stream cipher HC-128 in the eSTREAM final portfolio to show that the proposed design increases the performance without decreasing the security of the cipher.
stream cipher scalable data-width keystream estream random number generation