Efficient Blind Signatures for Accountability

The problem of building privacy-preserving accountability systems is long-standing and has been extensively studied by the network research community. We observe that blind signatures have potential to form critical building blocks of network security protocols, where an authority needs to vouch for the legitimacy of a message but there is also a need to keep the ownership of the message secret from the authority. Different forms of blind signature constructions exist in the literature and have found valuable use in areas such E-Cash technology and E-voting schemes. However, conventional blind signatures are quite heavyweight and thus, a direct application of these traditional signatures face scalability and performance challenges. In this paper, we present a novel third-order linear feedback shift register (LFSR) sequence-based, 2-party signature scheme, EGCLFSR, following a well-known variant of the generalized ElGamal signature scheme. Using EGCLFSR, and following fundamentals of a well known blind signature, originally used for E-Cash systems, we present an efficient blind signature BCLFSR (also the first blind signature based on LFSR sequences), which can serve as a protocol building block for privacy-preserving accountability systems. We perform a theoretical analysis including correctness and security of BCLFSR and also present a performance (computation and communication costs, storage overhead) comparison of the proposed scheme with well-known traditional constructions.