The healthcare Internet of Things (IoT), which relies on wearable devices to collect patient health data and aggregate it on cloud server, plays a key role in modern healthcare system. How to achieve bidirectional access control while ensuring secure information transmission is a significant challenge facing the healthcare industry. Identity-based matchmaking encryption (IB-ME) and attribute-based matchmaking encryption (AB-ME) show great research potential in achieving these functions. However, IB-ME schemes are typically limited to one-to-one scenarios. While AB-ME enables flexible many-to-many communication, its high communication overhead made it difficult for direct application in resource-constrained environments. Therefore, striking a balance between functionality and efficiency is crucial. Moreover, in healthcare IoT system, user deletion or revocation of decryption permission may be necessary due to the possibility of malicious behavior, organization changes, or discontinuing subscription services. To address these issues, this paper proposes an efficient revocable attribute-based matchmaking encryption (RAB-ME) scheme for healthcare IoT systems. This scheme not only supports bilateral access control but also enables user permission revocation while maintaining high efficiency. We analyzed the privacy and authenticity of this scheme based on the random oracle model. Through extensive comparisons and experimental simulations, our scheme outperforms existing approaches.

Matchmaking encryption constructed in the identity-based encryption setting, named identity-based matchmaking encryption (IB-ME), requires both sender and receiver to specify target identity simultaneously for each other for message decryption. The IB-ME schemes can not only ensure the privacy of the sender and the message but also provide authentication for the data source. In order to resist quantum-attacks, we put forward a post-quantum secure IB-ME scheme. Compared with Ateniese et al.'s scheme and Francati et al.'s scheme, our approach eliminates the use of functional encryption, predicate encryption and signature scheme, and only uses a more simple preimage sampling function and an IBE scheme in the way of non-black-box. Compared with post-quantum secure IB-MEs proposed currently, our scheme is the first non-black-box construction based on standard lattice assumptions such as LWE and ISIS.

Cloud 5G and Cloud 6G technologies are strong backbone infrastructures to provide high data rate and data storage with low latency for preserving QoS (Quality of Service) and QoE (Quality of Experience) in applications such as driverless vehicles, drone-based deliveries, smart cities and factories, remote medical diagnosis and surgery, and artificial-intelligence-based personalized assistants. There are many techniques to support the aforementioned applications, but for privacy preservation of Cloud 5G, the existing methods are still not sufficient. Public key encryption (PKE) scheme is an important means to protect user data privacy in Cloud 5G. Currently, the most common PKE used in Cloud 5G is CCA or CPA secure ones. However, its security level maybe not enough. SOA security is a stronger security standard than CPA and CCA. Roughly speaking, PKE with SOA security means that the adversary is allowed to open a subset of challenger ciphertexts and obtains the corresponding encrypted messages and randomness, but the unopended messages and randomness remain secure in the rest of the challenger ciphertexts. Security against SOA in PKEs has been a research hotspot, especially with the wide discussion in Cloud 5G. We revisited the SOA-CLE and proposed a new security proof, which is more concise and user friendly to understand privacy preservation in Cloud 5G applications.

Functional encryption (FE) can implement fine-grained control to encrypted plaintext via permitting users to compute only some specified functions on the encrypted plaintext using private keys with respect to those functions. Recently, many FEs were put forward; nonetheless, most of them cannot resist chosen-ciphertext attacks (CCAs), especially for those in the secret-key settings. This changed with the work, i.e., a generic transformation of public-key functional encryption (PK-FE) from chosen-plaintext (CPA) to chosen-ciphertext (CCA), where the underlying schemes are required to have some special properties such as restricted delegation or verifiability features. However, examples for such underlying schemes with these features have not been found so far. Later, a CCA-secure functional encryption from projective hash functions was proposed, but their scheme only applies to inner product functions. To construct such a scheme, some nontrivial techniques will be needed. Our key contribution in this work is to propose CCA-secure functional encryptions in the PKE and SK environment, respectively. In the existing generic transformation from (adaptively) simulation-based CPA- (SIM-CPA-) secure ones for deterministic functions to (adaptively) simulation-based CCA- (SIM-CCA-) secure ones for randomized functions, whether the schemes were directly applied to CCA settings for deterministic functions is not implied. We give an affirmative answer and derive a SIM-CCA-secure scheme for deterministic functions by making some modifications on it. Again, based on this derived scheme, we also propose an (adaptively) indistinguishable CCA- (IND-CCA-) secure SK-FE for deterministic functions. The final results show that our scheme can be instantiated under both nonstandard assumptions (e.g., hard problems on multilinear maps and indistinguishability obfuscation (IO)) and under standard assumptions (e.g., DDH, RSA, LWE, and LPN).

Abstract An aggregate signature refers to a signature, by which n signatures σ1,...,σn corresponding to n messages m1,...,mn and n users u1,...,un can be transformed into a single short signature . Besides, anyone can be convinced by the single short signature that the n messages m1,...,mn were definitely signed by the n users u1,...,un correspondingly. The concept of certificateless cryptography is proposed, so as to settle the key escrow problem in ID‐based cryptography and eliminate the demand for certificates in certified cryptography. A certificateless signature scheme was proposed by Chen et al. in 2014, which was extended into a certificateless aggregate signature scheme. In this paper, two attacks are firstly provided, so as to indicate that the certificateless signature scheme is insecure against a Type I adversary and a Type II adversary. And then, it is demonstrated that the certificateless aggregate signature scheme is not able to achieve the security levels they claimed due to the weaknesses of the certificateless signature scheme. Copyright © 2016 John Wiley & Sons, Ltd.

Abstract The notion of selective opening attacks (SOAs) was first introduced by Dworket al. at FOCS'99. Informally, an encryption scheme is SOA secure if an adversary is given a vector of ciphertexts and can adaptively corrupt some fraction of them by obtaining not only their messages but also their randomness, the uncorrupted ciphertexts retain secure. Provably achieving security against SOA has been proven extremely challenging. In this paper, we propose a security model to capture simulation‐based selective opening chosen‐plaintext attacks (SIM‐SO‐CPA) for certificateless encryption. We provide a concrete construction and prove its security in our simulation‐based selective opening chosen‐plaintext attack security model, based on the real or random and computational Diffie–Hellman assumptions. Compared with previous SOA‐secure public key encryption and identity‐based encryption, our certificateless encryption scheme is more simple and efficient. Copyright © 2017 John Wiley & Sons, Ltd.