Secure multiparty computation from threshold encryption based on class groups
发表信息
作者
- Lennart Braun
- Ivan Damgård
- Claudio Orlandi
笔记
We construct the first actively-secure threshold version of the cryptosystem based on class groups from the so-called CL framework (Castagnos and Laguillaumie, 2015).
We show how to use our threshold scheme to achieve general universally composable (UC) secure multiparty computation (MPC) with only transparent set-up, i.e., with no secret trapdoors involved.
On the way to our goal, we design new zero-knowledge (ZK) protocols with constant communication complexity for proving multiplicative relations between encrypted values. This allows us to use the ZK proofs to achieve MPC with active security with only a constant factor overhead.
Finally, we adapt our protocol for the so called “You-Only-Speak-Once” (YOSO) setting, which is a very promising recent approach for performing MPC over a blockchain. This is possible because our key generation protocol is simpler and requires significantly less interaction compared to previous approaches: in particular, our new key generation protocol allows the adversary to bias the public key, but we show that this has no impact on the security of the resulting cryptosystem.
我们构建了第一个基于类群的加密系统的主动安全阈值版本，该系统基于所谓的CL框架（Castagnos和Laguillaumie，2015）。
我们展示了如何利用我们的阈值方案实现一般的可普遍组合（UC）安全多方计算（MPC），仅需透明设置，即不涉及任何秘密陷阱。
在实现目标的过程中，我们设计了新的零知识（ZK）协议，具有恒定的通信复杂度，用于证明加密值之间的乘法关系。这使我们能够利用ZK证明以恒定的额外开销实现具有主动安全性的MPC。
最后，我们将我们的协议适配到所谓的“你只说一次”（YOSO）设置，这是一种在区块链上执行MPC的非常有前景的新方法。这是可能的，因为我们的密钥生成协议比以前的方法更简单，并且需要的交互显著减少：特别是，我们的新密钥生成协议允许对手对公钥施加偏差，但我们证明这对所得到的加密系统的安全性没有影响。