Mobile device and application (app) security are increasing important, partly due to the constant and fast-paced cyberthreat evolution. To ensure the security of communication (e.g. data-in-transit), a number of identity-based signature protocols have been designed to facilitate authorization identification and validation of messages. However, in many of these protocols, a user's private key may leak when a new signature is generated since the private keys are stored on the device. Seeking to improve the security of the private key, we propose a novel two-party distributed signing protocol for the IEEE P1363 standard in this paper. This protocol requires two devices to separately store one part of the user's private key, and allows these two devices to generate a valid signature without revealing the entire private key of the user. We formally prove the security of the protocol in the random oracle model. Then, we implement the protocol using the MIRACL library and evaluate the protocol on two Android devices. Compared with the protocol of Lindell (CRYPTO'17) that uses zero-knowledge for its security, we demonstrate that our protocol is more suitable for deployment in the mobile environment.

Rapid advances in wireless communications, hardware/software and Internet technologies have contributed to an exponential growth in the number of users accessing the Internet using mobile, wearable or other Internet of Things (IoT) devices. Identity-based signature schemes have been widely applied to enforce user authorization and validate user messages in mobile wireless networks. However, the user’s private key used to generate signatures is prone to leakage because the key is being stored on the mobile device. Several (t,n) threshold secret sharing schemes have been proposed to address the issue. One limitation is that the private keys in most of those schemes have to be recovered on a single device when generating signatures, so that the user who holds the device can sign any message without the participation of other users. To address the recovery limitation, we propose an efficient and secure two-party distributed signing protocol for the identity-based signature scheme in the IEEE P1363 standard, where two users can generate a valid signature without recovering the whole private key. We formally prove its security under a non-standard assumption. We also implemented our proposed protocol using the MIRACL Cryptographic software development kit. The experimental results obtained show that the time it takes for two general Android devices to generate a signature is about 709.53 milliseconds.

The Internet of Things and cloud services have been widely adopted in many applications, and personal health records (PHR) can provide tailored medical care. The PHR data is usually stored on cloud servers for sharing. Weighted ABE is a practical and flexible technique to protect PHR data. Under a weighted ABE policy, the data user's attributes will be “scored”, if and only if the score reaches the threshold value, they can access the data. However, while this approach offers a flexible access policy, the data owners have difficulty controlling their privacy, especially sharing PHR data in collaborative e-health systems. This paper aims to find a balance between privacy and flexibility and proposes an AND-weighted ABE scheme in cloud-based personal health records sharing systems. The proposed scheme can meet both privacy and flexibility. Only when the data user satisfies the scored-based policy and is in the specified organization(s), can the data user access the PHR data. Besides, we give the security proof and the performance evaluation of the proposed scheme. The security proof and performance analysis show that the proposed scheme can efficiently and securely share PHR data in cloud service.

The rapid development of the Internet of Things has contributed to the emergence of novel applications in recent years, such as wireless body area networks (WBANs). The latter can potentially provide people with convenience and high-quality healthcare. However, how to protect the confidentiality and privacy of user data remains challenging. Although a number of schemes using cryptographic tools in WBANs have been proposed, they are not practical due to the low computing power and storage capabilities of the sensors. To remedy this shortcoming, in this article, we propose an efficient obfuscation for encrypted identity-based signatures in WBANs, which can securely and efficiently use the resources of mobile devices to sign and encrypt data collected by sensors. In particular, our proposed scheme employs the identity-based signature scheme in the IEEE P1363 standard. We prove the security of our scheme, and that it satisfies the virtual black box properties. Moreover, we implement our scheme using the Java pairing-based cryptography library on a laptop and an Android phone. The experimental results the utility of our scheme in WBANs.