Earphones can give access to sensitive information via voice assistants which demands security methods that prevent unauthorized use. Therefore, we developed EarCapAuth, an authentication mechanism using 48 capacitive electrodes embedded into the soft silicone eartips of two earables. For evaluation, we gathered capactive ear canal measurements from 20 participants in 20 wearing sessions (12 at rest, 8 while walking). A per user classifier trained for authentication achieves an EER of 7.62% and can be tuned to a FAR (False Acceptance Rate) of 1% at FRR (False Rejection Rate) of 16.14%. For identification, EarCapAuth achieves 89.95%. This outperforms some earable biometric principles from related work. Performance under motion slightly decreased to 9.76% EER for authentication and 86.40% accuracy for identification. Enrollment can be performed rapidly with multiple short earpiece insertions and a biometric decision is made every 0.33s. In the future, EarCapAuth could be integrated into high-resolution brain sensing electrode tips.

翻译：耳机可通过语音助手访问敏感信息，这要求采用安全方法防止未授权使用。为此，我们开发了EarCapAuth——一种利用嵌入两个耳戴式设备软硅胶耳塞中的48个电容电极进行身份验证的机制。为进行评估，我们收集了20名参与者在20次佩戴会话（12次静息状态、8次行走状态）中的耳道电容测量数据。针对每位用户训练的身份验证分类器实现了7.62%的等错误率，并可调整为在16.14%错误拒绝率下达到1%错误接受率。在身份识别方面，EarCapAuth达到89.95%的准确率，优于相关研究中部分耳戴式生物特征识别方案。运动状态下的性能略有下降：身份验证等错误率为9.76%，身份识别准确率为86.40%。注册过程可通过多次短时耳塞插入快速完成，生物特征决策每0.33秒生成一次。未来，EarCapAuth可集成至高分辨率脑传感电极耳塞中。