DSA with SHA-1 for Space Telecommand Authentication: Analysis and Results

The issue of securing Telecommand data communications in civil and commercial space missions, by means of properly located security services and primitives, has been debated within the Security Working Group of the Consultative Committee for Space Data Systems since several months. In the context of Telecommand transmissions, that can be vital in determining a successful operational behavior of a space system, the interest is mainly focused on authentication, more than encryption. The object of this paper is to investigate, under the perspective of computational overhead, the possible applicability of a standard scheme, Digital Signature Algorithm with SHA-1, to the authentication of Telecommand data structures, and to discuss the pros and cons related to its adoption in such a peculiar context, through numerical simulations and comparison with an alternative solution relying on the widely used MD5 hash algorithm.