Biblio

Cloud data integrity verification was an important means to ensure data security. We used public key infrastructure (PKI) to manage user keys in Traditional way, but there were problems of certificate verification and high cost of key management. In this paper, RSA signature was used to construct a new identity-based cloud audit protocol, which solved the previous problems caused by PKI and supported forward security, and reduced the loss caused by key exposure. Through security analysis, the design scheme could effectively resist forgery attack and support forward security.

Ciphertext policy Attribute-based encryption (CPABE) plays an increasingly important role in the field of fine-grained access control for cloud storage. However, The exiting solution can not balance the issue of user identity tracking and user revocation. In this paper, we propose a CP-ABE scheme that supports association revocation and traceability. This scheme uses identity directory technology to realize single user revocation and associated user revocation, and the ciphertext re-encryption technology guarantees the forward security of revocation without updating the private key. In addition, we can accurately trace the identity of the user according to the decryption private key and effectively solve the problem of key abuse. This scheme is proved to be safe and traceable under the standard model, and can effectively control the computational and storage costs while maintaining functional advantages. It is suitable for the practical scenarios of tracking audit and user revocation.

In this paper, we propose a conditional privacy-preserving authentication scheme based on pseudonyms and (t,n) threshold secret sharing, named CPPT, for vehicular communications. To achieve conditional privacy preservation, our scheme implements anonymous communications based on pseudonyms generated by hash chains. To prevent bad vehicles from conducting framed attacks on honest ones, CPPT introduces Shamir (t,n) threshold secret sharing technique. In addition, through two one-way hash chains, forward security and backward security are guaranteed, and it also optimize the revocation overhead. The size of certificate revocation list (CRL) is only proportional to the number of revoked vehicles and irrelated to how many pseudonymous certificates are held by the revoked vehicles. Extensive simulations demonstrate that CPPT outperforms ECPP, DCS, Hybrid and EMAP schemes in terms of revocation overhead, certificate updating overhead and authentication overhead.

Considering application to communication among wireless sensors, Ma and Tsudik introduced the notion of forward-secure sequential aggregate (FssAgg) authentication in 2007. They also proposed an FssAgg MAC scheme composed of a MAC function and cryptographic hash functions at the same time. The security of their proposed scheme has not been analyzed yet and remains open. It is shown in this paper that a slight variant of the Ma-Tsudik FssAgg MAC scheme is secure under reasonable and standard assumptions on security of the underlying primitives. An efficient instantiation of the underlying MAC function using a cryptographic hash function is also discussed.

Secure logging as an indispensable part of any secure system in practice is well-understood by both academia and industry. However, providing security for audit logs on an untrusted machine in a large distributed system is still a challenging task. The emergence and wide availability of log management tools prompted plenty of work in the security community that allows clients or auditors to verify integrity of the log data. Most recent solutions to this problem focus on the space-efficiency or public verifiability of forward security. Unfortunately, existing secure audit logging schemes have significant performance limitations that make them impractical for realtime large-scale distributed applications: Existing cryptographic hashing is computationally expensive for logging in task intensive or resource-constrained systems especially to prove individual log events, while Merkle-tree approach has fundamental limitations when face with highly concurrent, large-scale log streams due to its serially appending feature. The verification step of Merkle-tree based approach requiring a logarithmic number of hash computations is becoming a bottleneck to improve the overall performance. There is a huge gap between the flux of log streams collected and the computational efficiency of integrity verification in the large-scale distributed systems. In this work, we develop a novel scheme, performance of which favorably compares with the existing solutions. The performance guarantees that we achieve stem from a novel data structure called concurrent authenticated tree, which allows log events concurrently appending and removes the need to wait for append operations to complete sequentially. We implement a prototype using chameleon hashing based on discrete log and Merkle history tree. A comprehensive experimental evaluation of the proposed and existing approaches is used to validate the analytical models and verify our claims. The results demonstrate that our proposed scheme verifying in a concurrent way is significantly more efficient than the previous tree-based approach.

The recently proposed file-injection type attacks are highlighting the importance of forward security in dynamic searchable symmetric encryption (DSSE). Forward security enables to thwart those attacks by hiding the information about the newly added files matching a previous search query. However, there are still only a few DSSE schemes that provide forward security, and they have factors that hinder efficiency. In particular, all of these schemes do not support actual data deletion, which increments both storage space and computational complexity. In this paper, we design and implement a forward secure DSSE scheme with optimal search and update complexity, for both computation and communication point of view. As a starting point, we propose a new, simple, theoretical data structure, called dual dictionary that can take advantage of both the inverted and the forward indexes at the same time. This data structure allows to delete data explicitly and in real time, which greatly improves efficiency compared to previous works. In addition, our scheme provides forward security by encrypting the newly added data with fresh keys not related with the previous search tokens. We implemented our scheme for Enron email and Wikipedia datasets and measured its performance. The comparison with Sophos shows that our scheme is very efficient in practice, for both searches and updates in dynamic environments.

In this paper, a mutual authentication protocol based on ECC is designed for RFID systems. This protocol is described in detail and the performance of this protocol is analyzed. The results show that the protocol has many advantages, such as mutual authentication, confidentiality, anonymity, availability, forward security, scalability and so on, which can resist camouflage attacks, tracking attacks, denial of service attacks, system internal attack.

We propose a lightweight RFID authentication protocol that supports forward and backward security. The only cryptographic mechanism that this protocol uses is a pseudorandom number generator (PRNG) that is shared with the backend Server. Authentication is achieved by exchanging a few numbers (3 or 5) drawn from the PRNG. The lookup time is constant, and the protocol can be easily adapted to prevent online man-in-the-middle relay attacks. Security is proven in the UC security framework.