With the rapid development of health equipments, increasingly more patients have installed the implantable medical devices (IMD) in their bodies for diagnostic, monitoring, and therapeutic purposes. IMDs are extremely limited in computation power and battery capacity. Meanwhile, IMDs have to communicate with an external programmer device (i.e., IMD programmer) through the wireless channel, which put them under the risk of unauthorized access and malicious wireless attacks. In this paper, we propose a proxy-based fine-grained access control scheme for IMDs, which can prolong the IMD's lifetime by delegating the access control computations to the proxy device (e.g., smartphone). In our scheme, the proxy communicates with the IMD programmer through an audio cable, which is resistant to a number of wireless attacks. Additionally, we use the ciphertext-policy attribute-based encryption (CP-ABE) to enforce fine-grained access control. The proposed scheme is implemented on real emulator devices and evaluated through experimental tests. The experiments show that the proposed scheme is lightweight and effective.
We propose a proximity-based access control scheme for implantable medical devices (IMDs). Our scheme is based on ultrasonic distance-bounding and enables an implanted medical device to grant access to its resources only to those devices that are in its close proximity. We demonstrate the feasibility of our approach through tests in an emulated patient environment. We show that, although implanted, IMDs can successfully verify the proximity of other devices with high accuracy. We propose a set of protocols that support our scheme, analyze their security in detail and discuss possible extensions. We make new observations about the security of implementations of ultrasonic distance-bounding protocols. Finally, we discuss the integration of our scheme with existing IMD devices and with their existing security measures. Implantable and wearable medical devices are used for monitoring, diagnosis, and treatment of an ever-increasing range of medical conditions, leading to an improved quality of life for patients. The addition of wireless connectivity to medical devices has enabled post-deployment tuning of therapy and access to device data virtually anytime and anywhere but, at the same time, has led to the emergence of security attacks as a critical concern. While cryptography and secure communication protocols may be used to address most known attacks, the lack of a viable secure connection establishment and key exchange mechanism is a fundamental challenge that needs to be addressed. We propose a vibration-based secure side channel between an external device (medical programmer or smartphone) and a medical device. Vibration is an intrinsically short-range, user-perceptible channel that is suitable for realizing physically secure communication at low energy and size weight overheads. We identify and address key challenges associated with the vibration channel, and propose a vibration-based wakeup and key exchange scheme, named SecureVibe, that is resistant to battery drain attacks. We analyze the risk of acoustic eavesdropping attacks and propose an acoustic masking countermeasure. We demonstrate and evaluate vibration-based wakeup and key exchange between a smartphone and a prototype medical device in the context of a realistic human body model. Implantable Medical Devices (IMDs) are widely used to treat chronic diseases. Nowadays, many IMDs can wirelessly communicate with an outside programmer (reader). However, the wireless access also introduces security concerns. An attacker may get an IMD reader and gain access to a patient's IMD. IMD security is an important issue since attacks on IMDs may directly harm the patient. A number of research groups have studied IMD security issues when the patient is in nonemergency situations. However, these security schemes usually require the patient's participation, and they may not work during emergencies (e.g., when the patient is in comma) for various reasons. In this paper, we propose a light-weight secure access control scheme for IMDs during emergencies. Our scheme utilizes patient's biometric information to prevent unauthorized access to IMDs. The scheme consists of two levels: level 1 employs some basic biometric information of the patient and it is lightweight; level 2 utilizes patients' iris data for authentication and it is very effective. In this research, we also make contributions in human iris verification: we discover that it is possible to perform iris verification by comparing partial iris data rather than the entire iris data. This significantly reduces the overhead of iris verification, which is critical for resource-limited IMDs. We evaluate the performance of our schemes by using real iris data sets. Our experimental results show that the secure access control scheme is very effective and has small overhead (hence feasible for IMDs). Specifically, the false acceptance rate (FAR) and false rejection rate (FRR) of our secure access control scheme are close to 0.000 with suitable threshold, and the memory and computation overheads are acceptable. Our analysis shows that the secure access control scheme reduces computation overhead by an average of 58 . In order for two sensors within a body area network to determine they are on the same body, e.g., for security purposes, extensive prior work considers the use of physiological values. We study the practicality of using body physiological values for securely exchanging messages for sharing keys. Due to its popularity in the literature, we use electrocardiography (ECG) signals, and show that cardiac physiology is incompatible with such schemes, due to the sensitivity to a node's deployment location on the body and the outsiders' capability to remotely sense the physiological value. As a solution for key sharing, we inject an artificial voltage signal to build a communication channel secure against an outsider. By implementing our scheme on a dead mouse and analyzing the human body channel characteristic with empirical data, we demonstrate the practicality of our scheme for body area network applications. We present Heart-to-Heart (H2H), a system to authenticate external medical device controllers and programmers to Implantable Medical Devices (IMDs). IMDs, which include pacemakers and cardiac defibrillators, are therapeutic medical devices partially or wholly embedded in the human body. They often have built-in radio communication to facilitate non-invasive reprogramming and data readout. Many IMDs, though, lack well designed authentication protocols, exposing patients to over-the-air attack and physical harm. H2H makes use of ECG (heartbeat data) as an authentication mechanism, ensuring access only by a medical instrument in physical contact with an IMD-bearing patient. Based on statistical analysis of real-world data, we propose and analyze new techniques for extracting time-varying randomness from ECG signals for use in H2H. We introduce a novel cryptographic device pairing protocol that uses this randomness to protect against attacks by active adversaries, while meeting the practical challenges of lightweight implementation and noise tolerance in ECG readings. Finally, we describe an end-to-end implementation in an ARM-Cortex M-3 microcontroller that demonstrates the practicality of H2H in current IMD hardware. Previous schemes have had goals much like those of H2H, but with serious limitations making them unfit for deployment---such as naively designed cryptographic pairing protocols (some of them recently broken). In addition to its novel analysis and use of ECG entropy, H2H is the first physiologically-based IMD device pairing protocol with a rigorous adversarial model and protocol analysis. Implantable medical devices (IMDs) improve patients' quality of life and help sustain their lives. In this study, we explore patient views and values regarding their devices to inform the design of computer security for wireless IMDs. We interviewed 13 individuals with implanted cardiac devices. Key questions concerned the evaluation of 8 mockups of IMD security systems. Our results suggest that some systems that are technically viable are nonetheless undesirable to patients. Patients called out a number of values that affected their attitudes towards the systems, including perceived security, safety, freedom from unwanted cultural and historical associations, and self-image. In our analysis, we extend the Value Sensitive Design value dams and flows technique in order to suggest multiple, complementary systems; in our discussion, we highlight some of the usability, regulatory, and economic complexities that arise from offering multiple options. We conclude by offering design guidelines for future security systems for IMDs.