Biblio

In asymmetric group key agreement (ASGKA) protocols, a group of users establish a common encryption key which is publicly accessible and compute pairwise different decryption keys. It is left as an open problem to design an ASGKA protocol with traitor traceability in Eurocrypt 2009. A one-round dynamic authenticated ASGKA protocol with public traitor traceability is proposed in this study. It provides a black-box tracing algorithm. Ind-CPA security with key compromise impersonation resilience (KCIR) and forward secrecy of ASGKA protocols is formally defined. The proposed protocol is proved to be Ind-CPA secure with KCIR and forward secrecy under D k-HDHE assumption. It is also proved that the proposed protocol resists collusion attack. In Setup algorithm and Join algorithm, one communication round is required. In Leave algorithm, no message is required to be transmitted. The proposed protocol adopts O(log N)-way asymmetric multilinear map to make the size of public key and the size of ciphertext both achieve O(logN), where N is the number of potential group members. This is the first ASGKA protocol with public traitor traceability which is more efficient than trivial construction of ASGKA protocols.

Public key cryptographic primitive (e.g., the famous Diffie-Hellman key agreement, or public key encryption) has recently been used as a standard building block in authenticated key agreement (AKA) constructions for wireless sensor networks (WSNs) to provide perfect forward secrecy (PFS), where the expensive cryptographic operation (i.e., exponentiation calculation) is involved. However, realizing such complex computation on resource-constrained wireless sensors is inefficient and even impossible on some devices. In this work, we introduce a new AKA scheme with PFS for WSNs without using any public key cryptographic primitive. To achieve PFS, we rely on a new dynamic one-time authentication credential that is regularly updated in each session. In particular, each value of the authentication credential is wisely associated with at most one session key that enables us to fulfill the security goal of PFS. Furthermore, the proposed scheme enables the principals to identify whether they have been impersonated previously. We highlight that our scheme can be very efficiently implemented on sensors since only hash function and XOR operation are required.

Outsourcing data storage and IT workloads to a third-party cloud provider introduces some security risks and time performance degradation. Moreover, controlling access to this data becomes very difficult when the volume of the data and number of users is very high. Various access control techniques have been proposed to address this issue. However, those techniques have complex schemes which are costly to be applied in real scenarios and they have limited flexibility and scalability to large volumes of data and users. In this paper we propose ESSAC which is an enhanced version of the SSAC scheme. ESSAC introduces a fine-grained access control scheme based on a classified Attribute Based Encryption, Role Based Encryption and Single Key Encryption methodology which achieves highest security without degrading the performance. We validate our scheme using a simulation on top of Amazon S3 and compare it to current schemes.

Delay-Tolerant Networks exhibit highly asynchronous connections often routed over many mobile hops before reaching its intended destination. The Bundle Security Protocol has been standardized providing properties such as authenticity, integrity, and confidentiality of bundles using traditional Public-Key Cryptography. Other protocols based on Identity-Based Cryptography have been proposed to reduce the key distribution overhead. However, in both schemes, secret keys are usually valid for several months. Thus, a secret key extracted from a compromised node allows for decryption of past communications since its creation. We solve this problem and propose the first forward secure protocol for Delay-Tolerant Networking. For this, we apply the Puncturable Encryption construction designed by Green and Miers, integrate it into the Bundle Security Protocol and adapt its parameters for different highly asynchronous scenarios. Finally, we provide performance measurements and discuss their impact.