Gennaro et al. showed, it is possible to dynamically increase the size of the signer group, without altering the public key. We extend this idea by removing members from the group, also without changing the public key. This is an important feature for dynamic groups, since it is very common, e.g. in meshed networks that members leave a group.
Gennaro et al. used RSA and bi-variate polynomials for their scheme. In contrast, we developed a DL-based scheme that uses ideas from the field of proactive secret sharing (PSS). One advantage of our scheme is the possibility to use elliptic curve cryptography and thereby decrease the communication and computation complexity through a smaller security parameter.
Our proposal is an efficient threshold cryptosystem that is able to adapt the group size in both directions. Since it is not possible to realize a non-interactive scheme with the ability to remove members (while the public key stays unchanged), we realized an interactive scheme whose communication efficency is highly optimized to compete with non-interactive schemes. Our contribution also includes a security proof for our threshold scheme.Category / Keywords: public-key cryptography / Public-key cryptosystem, threshold cryptosystem, dynamic adding, dynamic removing, dynamic membership, secret sharing, proactive Date: received 2 Sep 2008 Contact author: andreas noack at rub de Available format(s): PDF | BibTeX Citation Version: 20080907:024722 (All versions of this report) Discussion forum: Show discussion | Start new discussion