Anonymous Committed Broadcast is a functionality that extends DC-nets and allows a set of clients to privately commit messages to set of servers, which can then simultaneously open all committed messages in a random ordering. Anonymity holds since no one can learn the ordering or the content of the client's committed message. We present Blinder, the first system that provides a scalable and fully robust solution for anonymous committed broadcast. Blinder maintains both properties of security (anonymity) and robustness (aka. 'guaranteed output delivery' or 'availability') in the face of a global active (malicious) adversary. Moreover, Blinder is censorship resistant, that is, an honest client cannot be blocked from participating. Blinder obtains its security and scalability by carefully combining classical and state-of-the-art techniques from the fields of anonymous communication and secure multiparty computation (MPC). Relying on MPC for such a system is beneficial since it naturally allows the parties (servers) to enforce some properties on accepted messages prior their publication. A GPU based implementation of Blinder with 5 servers, which accepts 1 million clients, incurs a latency of less than 8 minutes; faster by a factor of 100 than the 3-servers Riposte protocol (S&P '15), which is not robust and not censorship resistant; we get an even larger factor when comparing to AsynchroMix and PowerMix (CCS '19), which are the only ones that guarantee fairness (or robustness in the online phase).
|Title of host publication||CCS 2020 - Proceedings of the 2020 ACM SIGSAC Conference on Computer and Communications Security|
|Publisher||Association for Computing Machinery|
|Number of pages||20|
|State||Published - 30 Oct 2020|
|Event||27th ACM SIGSAC Conference on Computer and Communications Security, CCS 2020 - Virtual, Online, United States|
Duration: 9 Nov 2020 → 13 Nov 2020
|Name||Proceedings of the ACM Conference on Computer and Communications Security|
|Conference||27th ACM SIGSAC Conference on Computer and Communications Security, CCS 2020|
|Period||9/11/20 → 13/11/20|
Bibliographical noteFunding Information:
This work has been partially funded by the BIU Center for Research in Applied Cryptography and Cyber Security in conjunction with the Israel National Cyber Bureau in the Prime Minister’s Office, and by a grant from the Israel Science Foundation. We thank Assi Barak, Moriya Farbstein, Igor Golikov, Lior Koskas, Meital Levi, Oren Tropp, Udi Wieder and Shahar Zadok for valuable discussion and their contribution to the implementation and the experiments.
© 2020 ACM.
- anonymous broadcast
- secure multiparty computation