Abstract A redactable consortium blockchain (RCB) can build a trust layer for industrial internet of things (IIoT) so as to enable IIoT to resist certain powerful attacks resulting in improper block content. The redactability is particularly important for blockchains applied in IIoT with valuable or sensitive activities such as financial IoT or energy-trading IoT. Huang et al. proposed a threshold chameleon hash (TCH) scheme and then constructed an accountable-and-sanitizable chameleon signature scheme based on TCH. These two primitives are further used as fundamental modules to build an RCB, which empowers IIoT devices to operate the blockchain in a controllable way. However, our paper shows that Huang et al.’s RCB suffers from a security problem that weakens the crucial redactability. Specifically, we find out that if a transaction in a given block is legally redacted by all authorized sensors who collectively hold the private redacting key, anyone (without any private information) can further redact this redacted transaction and delete any transaction within this redacted block and, meanwhile, any sensor user with a private signing (not redacting) key can insert a forged transaction into this redacted block. We further address this threat by replacing the TCH module in Huang et al.’s RCB with our designed TCH.

Double-authentication-preventing signature (DAPS) is a novel signature notion proposed at ESORICS 2014. The double-authentication-preventing property means that any pair of signatures on two different messages with the same subject will result in an immediate collapse of the signature system. A few potential applications of DAPS have been discussed by its inventors, such as providing a kind of self-enforcement to discourage certificate authority (CA) from misbehaving in public key infrastructure and offering CA some cryptographic arguments to resist legal coercion. In this study, we focus on some fundamental issues on DAPS. We propose a new definition, which is slightly weakened but still reasonable and strong enough to capture the DAPS concept. We develop the new notion of invertible chameleon hash functions with key exposure. Then we propose a generic DAPS scheme, which is provably secure if the underlying invertible chameleon hash function with key exposure is secure. We instantiate this general construction to obtain the DAPS schemes respectively based on the well-known assumptions of integer factorization, Rivest-Shamir-Adleman (RSA), and computational Diffie-Hellman (CDH). They are more efficient than previous DAPS schemes. Furthermore, unlike previous constructions, the trusted setup condition is not needed by our DAPS schemes based on RSA and CDH.

With the development of cloud storage, how to protect the integrity of the data stored in the cloud becomes the clients’ major concern. Recently, Zhang et al. proposed a certificateless data integrity auditing scheme for cloud-assisted cyber-physical-social systems. However, we find that their scheme has some security flaws, i.e., if a client outsources a file with$m$blocks data and tags, the cloud server can store only one block of them, and pass the integrity auditing of the auditor. We refer to this attack as storing one block attack. Then, we give an improved scheme to amend these flaws.

This paper presents an identity-based dynamic authenticated group key agreement (DAGKA) protocol with following advantages. The algorithms of Setup and Join has only one round communication. There is no message exchange among members in Leave algorithm. Joining members cannot know previous session keys and leaving members cannot know future session keys. Its AKE-security is proved under Decisional Bilinear Diffie-Hellman (DBDH) assumption. The protocol can resist key control attack and has forward security.

Certificateless public key encryption (CLE) and certificate-based encryption (CBE) are motivated to simultaneously solve the heavy certificate management problem inherent in the traditional public key encryption (PKE) and the key escrow problem inherent in the identity-based encryption (IBE). Al-Riyami and Paterson proposed a general conversion from CLE to CBE, which is neat and natural. Kang and Park pointed out a flaw in their security proof. Wu et al. proposed another generic conversion from CLE to CBE which additionally involves collision resistant hash functions. It remains an open problem whether the generic conversion due to Al-Riyami and Paterson is provably secure or not. We are motivated to solve this open problem. Our basic idea is to enhance Type II adversary's power a little by allowing it to conditionally replace a user's public key. We first formalize a new security model of CLE in this way. Then, we succeed in proving that the Al-Riyami–Paterson generic conversion from CLE to CBE is secure, if the CLE scheme is secure in our new security model. Finally, a concrete provably secure CBE scheme is presented to demonstrate the applicability of our result.

Remote authentication has been widely studied and adapted in distributed systems. The security of remote authentication mechanisms mostly relies on one of or the combination of three factors: 1) something users know—password; 2) something users have—smart card; and 3) something users are—biometric characteristics. This paper introduces an efficient generic framework for three-factor authentication. The proposed generic framework enhances the security of existing two-factor authentication schemes by upgrading them to three-factor authentication schemes, without exposing user privacy. In addition, we present a case study by upgrading a secure two-factor authentication scheme to a secure three-factor authentication scheme. Furthermore, implementation analysis, formal proof, and privacy discussion are provided to show that the derived scheme is practical, secure, and privacy preserving.