Securing wireless medical implants using an ECG-based secret data sharing scheme

Wireless Implantable Medical Devices (IMDs), including pacemakers and cardiac defibrillators, often have built-in wireless modules in order to facilitate non-invasive programming and data read-out; however, most IMDs lack a security mechanism. The unique challenge is that IMDs should be able to be accessed by doctors at any legitimate hospital for emergency purposes, but conventional security mechanisms using keys or credentials cannot guarantee that doctors could obtain keys timely in emergency situations. To address this unique challenge, we present an ECG-based Secret Data Sharing (ESDS) scheme for securing wireless IMDs which does not require pre-deployed keys or credentials. The ESDS scheme makes use of electrocardiograph (ECG) features to hide a secret within the IMD before transmission, and then reveal the secret with simultaneously measured ECG features by an external programmer. This scheme can protect IMDs against eavesdropping and other active attacks. In addition, the scheme uses an improved fuzzy vault scheme in which hash functions are substituted for chaff points to hide genuine points on a polynomial. This improvement saves IMD resources in terms of memory and communications, making the ESDS scheme lightweight. Performance analysis shows that the ESDS scheme meets our design goal of security.