差分信任：具有纪元加权更新的动态多权威匿名凭证
Differential Trust: Dynamic Multi-Authority Anonymous Credentials with Epoch-Weighted Updates
- Tianjin University（天津大学）
- Zhejiang Sci-Tech University（浙江理工大学）
- Wuhan University（武汉大学）
机构由 AI 辅助整理，请以论文原文为准。
中文总结 AI 辅助
针对多权威匿名凭证中权威权重差异被忽视的问题，提出MA-ACEW模型及EB-PS签名原语，实现按权重签发与跨纪元高效更新，并证明安全性，聚合凭证展示仅需10.68毫秒。
中文摘要 AI 辅助
匿名凭证（ACs）是隐私保护认证的基础，允许用户在不泄露身份的情况下证明对属性的拥有权。最先进的匿名凭证系统将凭证签发分布在多个权威机构之间，通常采用Shamir秘密共享或聚合签名等技术。虽然这种方法增强了系统的鲁棒性并消除了单点故障，但在凭证签发阶段将所有权威机构等同对待。这种统一处理忽视了不同权威机构所持有的可信度或权益的差异。这一局限性在现代去中心化系统中变得尤为突出，例如权益证明（Proof-of-Stake）网络，其中节点之间固有的信任差异无法在凭证签发过程中被利用。为解决这一局限性，我们提出了基于纪元权重的多权威匿名凭证（MA-ACEW）的概念，这是第一个考虑权威机构在凭证签发中权重分布的多权威匿名凭证（MA-AC）模型。关键在于，MA-ACEW能够在权威机构权重分布跨纪元变化时实现高效的凭证更新。MA-ACEW的核心是我们新颖的纪元绑定Pointcheval-Sanders签名（EB-PS）原语，它将签名绑定到特定的时间纪元。这种时间绑定使得纪元内的基于权重的凭证签发以及跨纪元的非交互式高效凭证更新成为可能。我们形式化了EB-PS的EUF-eCMA不可伪造性要求，并证明我们的构造在一种新颖的STB-GPS假设下满足该要求。然后我们证明我们的MA-ACEW构造实现了不可伪造性、匿名性和盲性。最后，我们展示了证明EB-PS和MA-ACEW效率的基准测试。值得注意的是，展示一个由128个部分凭证聚合而成的凭证平均仅需10.68毫秒。
英文摘要
Anonymous credentials (ACs) are fundamental to privacy-preserving authentication, allowing users to prove possession of attributes without revealing their identities. State-of-the-art ACs distribute credential issuance across multiple authorities, typically employing techniques such as Shamir's secret sharing or aggregate signatures. While this approach enhances system robustness and eliminates a single point of failure, it treats all authorities equally in the credential issuance phase. This uniform treatment disregards the varying levels of trustworthiness or stake held by different authorities. Such a limitation has become particularly problematic in modern decentralized systems like Proof-of-Stake networks, where the inherent trust differentiation among nodes cannot be leveraged in the credential issuance process. To address this limitation, we propose the notion of Multi-Authority Anonymous Credentials with Epoch-Based Weights (MA-ACEW), the first Multi-Authority Anonymous Credential (MA-AC) model that considers authorities' weight distribution in credential issuance. Crucially, MA-ACEW enables efficient credential updates when authority weight distributions change across epochs. The core of MA-ACEW is our novel Epoch-Bound Pointcheval-Sanders Signature (EB-PS) primitive, which binds signatures to specific time epochs. This temporal binding enables both weight-based credential issuance within epochs and efficient non-interactive credential updates across epochs. We formalize the EUF-eCMA unforgeability requirement for EB-PS and prove our construction satisfies it under a novel STB-GPS assumption. We then prove that our MA-ACEW construction achieves unforgeability, anonymity, and blindness. Finally, we present benchmarks demonstrating the efficiency of EB-PS and MA-ACEW. Remarkably, presenting a credential aggregated from 128 partial ones takes only 10.68 ms on average.
