Centralised biometric identity systems expose users to single points of failure, opaque verification processes, and irreversible biometric compromise. Decentralised Identifiers (DIDs) and Verifiable Credentials (VCs) offer stronger privacy guarantees, yet their integration with biometric authentication and distributed verification remains insufficiently explored. This paper presents Ciphera, a decentralised biometric identity framework combining privacy-preserving facial recognition, multi-node verification, IPFS-based credential metadata storage, and blockchain-anchored revocation. Evaluated across functional, performance, security, and distributed consistency dimensions, Ciphera achieved an 81% functional success rate, with stable enrolment and authentication but measurable revocation propagation delays and occasional audit-log inconsistencies. Performance testing demonstrated sub-second p95 verification latency of approximately 820ms under concurrent multi-node conditions. Security analysis confirmed strong confidentiality and integrity guarantees, though incomplete liveness detection leaves susceptibility to deepfake and replay attacks. The results demonstrate the feasibility of decentralised biometric identity while identifying key engineering challenges for production-grade deployment.

翻译：中心化生物特征身份系统使用户面临单点故障、不透明的验证流程以及不可逆的生物特征泄露风险。去中心化标识符（DID）与可验证凭证（VC）提供了更强的隐私保障，但二者与生物特征认证及分布式验证的集成仍缺乏充分探索。本文提出Ciphera——一种结合隐私保护人脸识别、多节点验证、基于IPFS的凭证元数据存储及区块链锚定撤销机制的去中心化生物特征身份框架。经功能、性能、安全及分布式一致性多维度评估，Ciphera实现了81%的功能成功率，注册与认证过程稳定，但存在可测量的撤销传播延迟与偶发审计日志不一致问题。性能测试表明，在多节点并发场景下，p95验证延迟约为820毫秒，响应时间低于1秒。安全性分析确认其具备强机密性与完整性保障，然而不完善的活体检测机制使其易受深度伪造与重放攻击。研究结果验证了去中心化生物特征身份的可行性，同时揭示了生产级部署面临的关键工程挑战。