Threshold signatures are a fundamental cryptographic primitive used in many practical applications. As proposed by Boneh and Komlo (CRYPTO'22), TAPS is a threshold signature that is a hybrid of privacy and accountability. It enables a combiner to combine t signature shares while revealing nothing about the threshold t or signing quorum to the public and asks a tracer to track a signature to the quorum that generates it. However, TAPS has three disadvantages: it 1) structures upon a centralized model, 2) assumes that both combiner and tracer are honest, and 3) leaves the tracing unnotarized and static. In this work, we introduce Decentralized, Threshold, dynamically Accountable and Private Signature (DeTAPS) that provides decentralized combining and tracing, enhanced privacy against untrusted combiners (tracers), and notarized and dynamic tracing. Specifically, we adopt Dynamic Threshold Public-Key Encryption (DTPKE) to dynamically notarize the tracing process, design non-interactive zero knowledge proofs to achieve public verifiability of notaries, and utilize the Key-Aggregate Searchable Encryption to bridge TAPS and DTPKE so as to awaken the notaries securely and efficiently. In addition, we formalize the definitions and security requirements for DeTAPS. Then we present a generic construction and formally prove its security and privacy. To evaluate the performance, we build a prototype based on SGX2 and Ethereum.

翻译：阈值签名是一种基本密码学原语，广泛应用于实际场景。由Boneh和Komlo（CRYPTO'22）提出的TAPS是一种兼具隐私与可问责性的阈值签名方案。它允许组合者合并t个签名份额，同时不向公众泄露阈值t或签名法定人数的信息，并借助追踪者将签名追溯至生成它的法定人数。然而，TAPS存在三个缺陷：1）构建于中心化模型之上；2）假设组合者与追踪者均诚实；3）追踪过程无公证且为静态。本文提出去中心化、动态可问责与隐私保护阈值签名方案（DeTAPS），支持去中心化的组合与追踪，增强对非可信组合者（追踪者）的隐私保护，并实现可公证的动态追踪。具体而言，我们采用动态阈值公钥加密（DTPKE）动态公证追踪过程，设计非交互式零知识证明实现公证行为的公开可验证性，并利用密钥聚合可搜索加密桥接TAPS与DTPKE，从而安全高效地唤醒公证人。此外，我们形式化定义了DeTAPS的安全需求，给出通用构造方法并严格证明其安全性与隐私性。性能评估方面，我们基于SGX2与以太坊构建了原型系统。