A Wireless Body Area Network (WBAN), introduced into the healthcare sector to improve patient care and enhance the efficiency of medical services, also brings the risk of the leakage of patients’ privacy. Therefore, maintaining the communication security of patients’ data has never been more important. However, WBAN faces issues such as open medium channels, resource constraints, and lack of infrastructure, which makes the task of designing a secure and economical communication scheme suitable for WBAN particularly challenging. Signcryption has garnered attention as a solution suitable for resource-constrained devices, offering a combination of authentication and confidentiality with low computational demands. Although the advantages offered by existing certificateless signcryption schemes are notable, most of them only have proven security within the random oracle model (ROM), lack public ciphertext authenticity, and have high computational overheads. To overcome these issues, we propose a certificateless anonymous signcryption (CL-ASC) scheme suitable for WBAN, featuring anonymity of the signcrypter, public verifiability, and public ciphertext authenticity. We prove its security in the standard model, including indistinguishability, unforgeability, anonymity of the signcrypter, and identity identifiability, and demonstrate its superiority over relevant schemes in terms of security, computational overheads, and storage costs.

With superior computing power and efficient data collection capability, Internet of Medical Things (IoMT) significantly improves the accuracy and convenience of medical work. As most communications are over open networks, it is critical to encrypt data to ensure confidentiality before uploading them to cloud storage servers (CSSs). Public key encryption with keyword search (PEKS) allows users to search for specific keywords in ciphertext and plays an essential role in IoMT. However, PEKS still has the following problems: 1. As a semi-trusted third party, the CSSs may provide wrong search results to save computing and bandwidth resources. 2. Single-keyword searches often produce many irrelevant results, which is undoubtedly a waste of computing and bandwidth resources. 3. Most PEKS schemes rely on bilinear pairings, resulting in computational inefficiencies. 4. Public key infrastructure (PKI)-based or identity-based PEKS schemes face the problem of certificate management or key escrow. 5. Most PEKS schemes are vulnerable to offline keyword guessing attacks, online keyword guessing attacks, and insider keyword guessing attacks. We present a certificateless verifiable and pairing-free conjunctive public keyword searchable encryption (CLVPFC-PEKS) scheme. An efficiency analysis shows that the performance advantage of the new scheme is far superior to that of the existing scheme. More importantly, we provide proof of security under the standard model (SM) to ensure the reliability of the scheme in practical applications.

The Internet of Medical Things(IoMT) has powerful cloud computing ability and efficient data collection ability, which can improve the accuracy and convenience of medical work. As most communications are over open networks, data should encrypted before uploading to ensure the confidentiality of sensitive user data. Searching for encrypted data has become a challenging problem. Public key Encryption with Keyword Search (PEKS) supports the search of encrypted data and provides data privacy protection. PEKS has become a trendy technology, but PEKS still has the following problems: 1. The cloud server, as a semi-honest but curious third party, is likely to return some wrong search results to save computing and bandwidth resources. 2. The single keyword search inevitably produces irrelevant results, wasting computing and bandwidth resources. 3. Most PEKS schemes use bilinear pairing, so the computational efficiency is relatively low. 4. PEKS schemes based on Public Key Infrastructure (PKI) or identity-based cryptography inevitably face problems with certificate management or key escrow. 5. Most PEKS schemes face serious security threats such as Keyword Guessing Attacks (KGA) and File Injection Attacks (FIA). To solve the above problems, we propose a new certificateless verifiable bilinear pair-free conjunctive keyword search encryption scheme(CLVPFCKS) for IoMT using multi-signature.

Identity-based multi-proxy signatures (IBMPS) enable an original signer to delegate signing authority to multiple proxy signers, who jointly sign a common message on the original signer’s behalf using their identity-associated private keys. This supports authenticated collaborative reporting in unmanned aerial vehicle (UAV)-assisted rescue. We propose an IBMPS scheme for this application and a security model that captures adaptive queries and signer collusion. Under the computational Diffie–Hellman (CDH) assumption and the collision resistance of ${\widehat{H}}_2$ and ${\widehat{H}}_3$, we prove unforgeability for the three forgery scenarios of Game 1 in the standard model (SM), with explicit reduction bounds and no public-key replacement. We also analyze long-term private-key recovery under proxy signing-key exposure, assuming an honestly generated target public key that remains unchanged. The scheme verifies individual partial signatures before aggregation, while final verification requires a constant number of pairings and scalar multiplications; signer-list processing still depends on group size. Under historical benchmark timings and the adopted operation counts, with ten proxy signers, the estimated total computational cost is 19.34–44.00% lower than that of five of the six baseline schemes, and the estimated final verification cost is 50.26–74.06% lower than that of all six. Under the adopted encoding assumptions, the 20-byte long-term private-key representation is the smallest among the compared schemes, the 276-byte per-proxy delegation ties for the smallest, and the 532-byte final signature matches that of Shin et al.’s scheme. The cost figures are model-based estimates, and the byte counts are per-object representation sizes rather than complete end-to-end communication costs.