Decisional Diffie-Hellman Research Articles

Leakage-resilient CCA2-secure certificateless public-key encryption scheme without bilinear pairing

In practical applications, an encryption scheme should withstand various leakage attacks (e.g., side-channel attacks, cold-boot attacks, etc.). Thus, in this paper, a new leakage-resilient certificateless public-key encryption (LR-CL-PKE) scheme is presented, and whose security is based on the classic decisional Diffie–Hellman (DDH) assumption. Considering the computational costs, because without bilinear pairing, our construction is more efficient than traditional LR-CL-PKE schemes. Based on the hardness of the DDH assumption, the security of our proposal is proved. Furthermore, in the leakage setting, our construction can keep its claimed security even if the adversary can learn a certain amount of additional information on the secret key through various leakage attacks.

Searchable attribute-based encryption scheme with attribute revocation in cloud storage.

Attribute based encryption (ABE) is a good way to achieve flexible and secure access control to data, and attribute revocation is the extension of the attribute-based encryption, and the keyword search is an indispensable part for cloud storage. The combination of both has an important application in the cloud storage. In this paper, we construct a searchable attribute-based encryption scheme with attribute revocation in cloud storage, the keyword search in our scheme is attribute based with access control, when the search succeeds, the cloud server returns the corresponding cipher text to user and the user can decrypt the cipher text definitely. Besides, our scheme supports multiple keywords search, which makes the scheme more practical. Under the assumption of decisional bilinear Diffie-Hellman exponent (q-BDHE) and decisional Diffie-Hellman (DDH) in the selective security model, we prove that our scheme is secure.

IMPLEMENTING CLOUD REVOCATION AUTHORITY WITH IDENTITY BASED ENCRYPTION AND ITS APPLICATIONS

Identity-based encryption(IBE) is a public key cryptosystem(encoding and decoding) and eliminates the demands of public key infrastructure(PKI) and certificate administration in conventional public key settings. Due to the absence of PKI, the revocation problem is a critical issue in IBE settings. Several revocable IBE schemes have been proposed regarding this issue. Quite recently, by embedding an outsourcing computation technique into IBE, a revocable IBE scheme with a key-update cloud service provider (KU-CSP) was proposed.However, their scheme has two shortcomings. One is that the computation and communication costs are higher than previous revocable IBE schemes. The other shortcoming is lack of scalability in the sense that the KU-CSP must keep a secret value for each user. In the article, we propose a new revocable IBE scheme with a cloud revocation authority (CRA) to solve the two shortcomings namely, the performance is significantly improved and the CRA holds only a system secret for all the users. For security analysis, we demonstrate that the proposed scheme is semantically secure under the decisional bilinear Diffie-Hellman (DBDH) assumption. Finally,we extend the proposed revocable IBE scheme to present a CRA-aided authentication scheme with period-limited privileges for managing a large number of various cloud services.

Efficient KDM-CCA Secure Public-Key Encryption via Auxiliary-Input Authenticated Encryption

KDM[F]-CCA security of public-key encryption (PKE) ensures the privacy of key-dependent messages f(sk) which are closely related to the secret key sk, where f∈F, even if the adversary is allowed to make decryption queries. In this paper, we study the design of KDM-CCA secure PKE. To this end, we develop a new primitive named Auxiliary-Input Authenticated Encryption (AIAE). For AIAE, we introduce two related-key attack (RKA) security notions, including IND-RKA and weak-INT-RKA. We present a generic construction of AIAE from tag-based hash proof system (HPS) and one-time secure authenticated encryption (AE) and give an instantiation of AIAE under the Decisional Diffie-Hellman (DDH) assumption. Using AIAE as an essential building block, we give two constructions of efficient KDM-CCA secure PKE based on the DDH and the Decisional Composite Residuosity (DCR) assumptions. Specifically, (i) our first PKE construction is the first one achieving KDM[Faff]-CCA security for the set of affine functions and compactness of ciphertexts simultaneously. (ii) Our second PKE construction is the first one achieving KDM[Fpolyd]-CCA security for the set of polynomial functions and almost compactness of ciphertexts simultaneously. Our PKE constructions are very efficient; in particular, they are pairing-free and NIZK-free.

Leakage-Resilient Certificateless Short Signature Scheme

For a certificateless short signature scheme to be applied in practical applications, it should without various leakage attacks. In this paper, we present a new leakage-resilient certificateless short signature scheme whose security is based on the classical decisional Diffie-Hellman (DDH) assumption. Our scheme is leakage-resilient signature scheme, and leaked information is a maximum value (upper bound). What is more, our scheme also enjoys a higher relative leaked information rate and still semantically secure against adaptive chosen message attack. Besides these good performance features, we have formally proved the security of our scheme in the random oracle model under the hardness of the DDH problem. With these import features, our proposal may have some significant value in the practical applications. Compared to existing schemes, our new scheme has two advantages: (1) Our scheme is leakage-resilient certificateless short signature scheme; (2) Our Scheme is leakage-resilient signature scheme, and leaked information is a maximum value (upper bound).

Expressive ciphertext-policy attribute-based encryption with direct user revocation

Attribute-based encryption enables fine-grained access control on sensitive data with a specific user set. However, traditional ABE schemes cannot satisfy practical requirements of data sharing applications where users may leave or join a system frequently. In this paper, a ciphertext-policy ABE scheme with direct user revocation (DUR-CP-ABE) is proposed. In DUR-CP-ABE, both the private key and the ciphertext contain partial components associated with a user identity and a revocation list, respectively. A user can decrypt a ciphertext if and only if he/she is not in the revocation list and his/her attribute set satisfies the access policy, simultaneously. In addition, whenever revocation events occur, only ciphertext components associated with the revocation list need to be updated. Finally, the DUR-CP-ABE scheme is proved selectively secure under the decisional q-bilinear Diffie-Hellman exponent assumption in the standard model. Compared with the existing revocation-related schemes, the new scheme can achieve high efficiency and ensure the expression ability of access structure.

Provably secure CL-KEM-based password-authenticated key exchange protocol

Traditional password-based authentication protocols are vulnerable to various password-related attacks, while public key cryptography PKC is expensive to manage certificates. Moreover, the traditional identity-based cryptography suffers to key escrow. To solve the above problems, we propose a password-based authentication and key exchange AKE protocol. The protocol is based on certificateless key encapsulation mechanism CL-KEM using the three-party setting. The security of this protocol is provable under the decisional Diffie-Hellman DDH assumption. Security analysis shows that this protocol can achieve mutual authentication and forward security, and it can resist various password-related attacks.

Strong authenticated key exchange with auxiliary inputs

Leakage attacks, including various kinds of side-channel attacks, allow an attacker to learn partial information about the internal secrets such as the secret key and the randomness of a cryptographic system. Designing a strong, meaningful, yet achievable security notion to capture practical leakage attacks is one of the primary goals of leakage-resilient cryptography. In this work, we revisit the modelling and design of authenticated key exchange (AKE) protocols with leakage resilience. We show that the prior works on this topic are inadequate in capturing realistic leakage attacks. To close this research gap, we propose a new security notion named leakage-resilient eCK model w.r.t. auxiliary inputs ( $$\mathsf {AI\hbox {-}LR\text{-}eCK}$$ ) for AKE protocols, which addresses the limitations of the previous models. Our model allows computationally hard-to-invert leakage of both the long-term secret key and the randomness, and also addresses a limitation existing in most of the previous models where the adversary is disallowed to make leakage queries during the challenge session. As another major contribution of this work, we present a generic framework for the construction of AKE protocols that are secure under the proposed $$\mathsf {AI\hbox {-}LR\text{-}eCK}$$ model. An instantiation based on the decision Diffie–Hellman (DDH) assumption in the standard model is also given to demonstrate the feasibility of our proposed framework.

Public‐key encryption indistinguishable under plaintext‐checkable attacks

Indistinguishability under chosen-ciphertext attack (IND-CCA) is now considered the de facto security notion for public-key encryption. However, this sometimes offers a stronger security guarantee than what is needed. In this study, the authors consider a weaker security notion, termed as indistinguishability under plaintext-checking attacks (IND-PCA), in which the adversary has only access to an oracle indicating whether or not a given ciphertext encrypts a given message. After formalising this notion, the authors design a new public-key encryption scheme satisfying it. The new scheme is a variant of the Cramer–Shoup encryption scheme with shorter ciphertexts. Its security is also based on the plain decisional Diffie–Hellman (DDH) assumption. Additionally, the algebraic properties of the new scheme allow proving plaintext knowledge using Groth–Sahai non-interactive zero-knowledge proofs or smooth projective hash functions. Finally, as a concrete application, the authors show that, for many password-based authenticated key exchange (PAKE) schemes in the Bellare–Pointcheval–Rogaway security model, they can safely replace the underlying IND-CCA encryption schemes with their new IND-PCA one. By doing so, they reduce the overall communication complexity of these protocols and obtain the most efficient PAKE schemes to date based on plain DDH.

An efficient and practical threshold gateway-oriented password-authenticated key exchange protocol in the standard model

With the assistance of an authentication server, a gateway-oriented password-authenticated key exchange (GPAKE) protocol can establish a common session key shared between a client and a gateway. Unfortunately, a GPAKE protocol becomes totally insecure if an adversary can compromise the authentication server and steal the passwords of the clients. In order to provide resilience against adversaries who can hack into the authentication server, we propose a threshold GPAKE protocol and then present its security proof in the standard model based on the hardness of the decisional Diffie-Hellman (DDH) problem. In our proposal, the password is shared among $n$ authentication servers and is secure unless the adversary corrupts more than $t+1$ servers. Our protocol requires $n>3t$ servers to work. Compared with existing threshold PAKE protocols, our protocol maintains both stronger security and greater efficiency.

Secure oblivious transfer protocol from indistinguishability obfuscation

A new secure oblivious transfer (OT) protocol from indistinguishability obfuscation (iO) is proposed in this paper. The candidate iO and a dual-mode cryptosystem are the main technical tools of this scheme. Garg et al. introduced a candidate construction of iO in 2013. Following their steps, a new k-out-of-l OT protocol is presented here, and its realization from decisional Diffie-Hellman (DDH) is described in this paper, in which iO was combined with the dual-mode cryptosystem. The security of the scheme mainly relies on the indistinguishability of the obf-branches (corresponding to the two modes in dual-mode model). This paper explores a new way for the application of iO.

Provably Secure Threshold-Based ABE Scheme Without Bilinear Map

In several distributed environments, users can decrypt a secret message using a certain number of valid attributes or credentials. Attribute-based encryption (ABE) is the most promising technique to achieve such fine-grain access control. In recent years, many ABE schemes have been proposed, but most of them are constructed based on the concept of pairing and secret sharing scheme. This paper aims at presenting a pairing-free threshold-based ABE scheme (PT-ABE) over multiplicative group. The propose work is secured under the standard decisional Diffie–Hellman (DDH) assumption, and both error-tolerant and collusion-free. The scheme does not consider random oracle operation to prove its security. We compare the PT-ABE scheme with other relevant ABE schemes and find that our scheme is much more efficient and flexible than others. Besides, we propose a protocol based on PT-ABE scheme and show that PT-ABE is perfectly suitable in cloud environment to provide cloud security. To the best of our knowledge, the proposed scheme should be implemented in real- life distributed scenarios, as it is well secured, flexible and perform better than existing ones.

Towards efficient sharing of encrypted data in cloud-based mobile social network

Mobile social network is becoming more and more popular with respect to the development and popularity of mobile devices and interpersonal sociality. As the amount of social data increases in a great deal and cloud computing techniques become developed, the architecture of mobile social network is evolved into cloud-based that mobile clients send data to the cloud and make data accessible from clients. The data in the cloud should be stored in a secure fashion to protect user privacy and restrict data sharing defined by users. Ciphertext-policy attribute-based encryption (CP-ABE) is currently considered to be a promising security solution for cloud-based mobile social network to encrypt the sensitive data. However, its ciphertext size and decryption time grow linearly with the attribute numbers in the access structure. In order to reduce the computing overhead held by the mobile devices, in this paper we propose a new Outsourcing decryption and Match-then-decrypt CP-ABE algorithm (OM-CP-ABE) which firstly outsources the computation-intensive bilinear pairing operations to a proxy, and secondly performs the decryption test on the attributes set matching access policy in ciphertexts. The experimental performance assessments show the security strength and efficiency of the proposed solution in terms of computation, communication, and storage. Also, our construction is proven to be replayable choosen-ciphertext attacks (RCCA) secure based on the decisional bilinear Diffie-Hellman (DBDH) assumption in the standard model.

Achieving Data Confidentiality And Access Control Through Ciphertext Property Based on Symmetric Encryption with Undeniable Assignment

In the cloud, for achieving access control and keeping data confidential, the data owners could adopt attribute-based encryption to encrypt the stored data. Users with limited computing power are however more likely to delegate the mask of the decryption task to the cloud servers to reduce the computing cost. As a result, attribute-based encryption with delegation emerges. Still, there are caveats and questions remaining in the previous relevant works. For instance, during the delegation, the cloud servers could tamper or replace the delegated ciphertext and respond a forged computing result with malicious intent. They may also cheat the eligible users by responding them that they are ineligible for the purpose of cost saving. Furthermore, during the encryption, the access policies may not be flexible enough as well. Since policy for general circuits enables to achieve the strongest form of access control, a construction for realizing circuit ciphertext-policy attribute-based hybrid encryption with verifiable delegation has been considered in our work. In such a system, combined with verifiable computation and encrypt-then-mac mechanism, the data confidentiality, the fine-grained access control and the correctness of the delegated computing results are well guaranteed at the same time. Besides, our scheme achieves security against chosen-plaintext attacks under the k-multilinear Decisional Diffie-Hellman assumption. Moreover, an extensive simulation campaign confirms the feasibility and efficiency of the proposed solution. Index Terms—Ciphertext-policy attribute-based encryption, Circuits, Verifiable delegation, Multilinear map, Hybrid encryption. F

Reconciling Non-malleability with Homomorphic Encryption

Homomorphic encryption schemes are useful in designing conceptually simple protocols that operate on encrypted inputs. On the other hand, non-malleable encryption schemes are vital for designing protocols with robust security against malicious parties, in a composable setting. In this paper, we address the problem of constructing public-key encryption schemes that meaningfully combine these two opposing demands. The intuitive tradeoff we desire in an encryption scheme is that anyone should be able to change encryptions of unknown messages \(m_1, \ldots , m_k\) into a (fresh) encryption of \(T(m_1, \ldots , m_k)\) for a specific set of allowed functions T, but the scheme should be otherwise “non-malleable.” That is, no adversary should be able to construct a ciphertext whose value is related to that of other ciphertexts in any other way. For the case where the allowed functions T are all unary, we formulate precise definitions that capture our intuitive requirements and show relationships among these new definitions and other more standard ones (IND-CCA, gCCA, and RCCA). We further justify these new definitions by showing their equivalence to a natural formulation of security in the framework of Universally Composable security. Next, we describe a new family of encryption schemes that satisfy our definitions for a wide variety of allowed transformations T and prove their security under the Decisional Diffie-Hellman (DDH) assumption in two groups with related sizes. Finally, we demonstrate how encryption schemes that satisfy our definitions can be used to implement conceptually simple protocols for non-trivial computation on encrypted data, which are secure against malicious adversaries in the UC framework without resorting to general-purpose multi-party computation or zero-knowledge proofs. For the case where the allowed functions T are binary, we show that a natural generalization of our definitions is unattainable if some T is a group operation. On the positive side, we show that if one of our security requirements is relaxed in a natural way, we can in fact obtain a scheme that is homomorphic with respect to (binary) group operations, and non-malleable otherwise.

Multi-authority proxy re-encryption based on CPABE for cloud storage systems

The dissociation between data management and data ownership makes it difficult to protect data security and privacy in cloud storage systems. Traditional encryption technologies are not suitable for data protection in cloud storage systems. A novel multi-authority proxy re-encryption mechanism based on ciphertext-policy attribute-based encryption (MPRE-CPABE) is proposed for cloud storage systems. MPRE-CPABE requires data owner to split each file into two blocks, one big block and one small block. The small block is used to encrypt the big one as the private key, and then the encrypted big block will be uploaded to the cloud storage system. Even if the uploaded big block of file is stolen, illegal users cannot get the complete information of the file easily. Ciphertext-policy attribute-based encryption (CPABE) is always criticized for its heavy overload and insecure issues when distributing keys or revoking user's access right. MPRE-CPABE applies CPABE to the multi-authority cloud storage system, and solves the above issues. The weighted access structure (WAS) is proposed to support a variety of fine-grained threshold access control policy in multi-authority environments, and reduce the computational cost of key distribution. Meanwhile, MPRE-CPABE uses proxy re-encryption to reduce the computational cost of access revocation. Experiments are implemented on platforms of Ubuntu and CloudSim. Experimental results show that MPRE-CPABE can greatly reduce the computational cost of the generation of key components and the revocation of user's access right. MPRE-CPABE is also proved secure under the security model of decisional bilinear Diffie-Hellman (DBDH).

Deterministic attribute-based encryption

Attribute-based encryption enables data owners to share their information by specifying access control policies while outsourcing their encrypted data to the cloud. However, there are no efficient searchable schemes over encrypted data in attribute-based setting. In this paper, we propose a novel primitive called deterministic attribute-based encryption DABE, which simultaneously supports data sharing and retrieving in time logarithmic in the size of the database. We formalise the security properties for DABE with respect to auxiliary inputs. Furthermore, we propose a generic construction in the random oracle model and a selectively secure concrete key-policy DABE in the standard model under decisional bilinear Diffie-Hellman assumption.

Round-optimal ID-based dynamic authenticated group key agreement

A group key agreement protocol provides a set of users with a shared secret key to achieve cryptographic goal. When membership changes, group session key should be updated efficiently and securely. Hence, dynamic group key agreement protocols are of practical significance. Identity-based group key agreement protocols are preferred to certificate-based ones since identity-based protocols can simplify public key management procedure. Most of previous dynamic group key agreement protocols need at least two rounds to establish or refresh group session keys. In this paper, an identity-based dynamic authenticated group key agreement DAGKA protocol is presented. It is round-optimal, since: 1 in setup and join algorithms, only one round of communication is required; 2 in leave algorithm, there is no message exchange among group members. Joining members cannot compute previous session keys and leaving members cannot compute subsequent session keys. The protocol is provably secure. Its AKE-security is proved under decisional bilinear Diffie-Hellman DBDH assumption. In addition, the protocol resists key control attack and achieves forward security.

Circuit Ciphertext-Policy Attribute-Based Hybrid Encryption with Verifiable Delegation in Cloud Computing

In the cloud, for achieving access control and keeping data confidential, the data owners could adopt attribute-based encryption to encrypt the stored data. Users with limited computing power are however more likely to delegate the mask of the decryption task to the cloud servers to reduce the computing cost. As a result, attribute-based encryption with delegation emerges. Still, there are caveats and questions remaining in the previous relevant works. For instance, during the delegation, the cloud servers could tamper or replace the delegated ciphertext and respond a forged computing result with malicious intent. They may also cheat the eligible users by responding them that they are ineligible for the purpose of cost saving. Furthermore, during the encryption, the access policies may not be flexible enough as well. Since policy for general circuits enables to achieve the strongest form of access control, a construction for realizing circuit ciphertext-policy attribute-based hybrid encryption with verifiable delegation has been considered in our work. In such a system, combined with verifiable computation and encrypt-then-mac mechanism, the data confidentiality, the fine-grained access control and the correctness of the delegated computing results are well guaranteed at the same time. Besides, our scheme achieves security against chosen-plaintext attacks under the $k$ -multilinear Decisional Diffie-Hellman assumption. Moreover, an extensive simulation campaign confirms the feasibility and efficiency of the proposed solution.

A Secure Delegation Process using Diffie-Hellman Assumption in Cloud Computing

for the purpose of privacy preserving. Additionally, the attribute based encryption method is used to enhance the confidentiality and access control. Delegation is a process which is performed by the users who are containing the less computing power. They delegate their decryption process to the cloud server to reduce the computation cost. This time the cloud server may change the given cipher text and sends the modified one to the data user for malicious attack. This time the access control cannot be malleable. To enhance the access control, we propose a circuit cipher text-policy attribute-based hybrid encryption with verifiable delegation method. For the authentication purpose, mac mechanism is added with the symmetric encryption technique. By this mechanism, we can certify the confidentiality of data, accuracy of the delegated computing results and enhance the access control. Our paper uses the k-multi linear Decisional Diffie-Hellman algorithm to improve the security to the encrypted data. This scheme takes only less computational and communication cost so it will be done at practically.