Security Analysis of Signcryption Scheme from q-Diffie-Hellman Problems

Recently, Duan and Cao proposed an multi-receiver identity-based signcryption scheme. They showed that their scheme is secure against adaptive chosen ciphertext attacks in the random oracle model. In this paper, we show that their scheme is in fact not secure against adaptive chosen ciphertext attacks under their defined security model.

In recent years, secure communication and privacy‐preserving are gaining popularity because of the advent of wireless network. Certificateless cryptography (CLC) and identity‐based cryptography (IBC) have already been widely applied in the area of wireless network. Hence, to achieve secure communication from CLC to IBC, we present a heterogeneous signcryption scheme that enables a sender in the CLC to transmit a message to multi‐receiver in the IBC. Our scheme has no restrictions on the system parameters and master keys; private key generator and key generating center generate their own system parameters and master key for the IBC users and the CLC user, separately. Considering privacy‐preserving in heterogeneous communication, we show that our scheme can realize the anonymity of all receivers. Compared with other schemes, our scheme has more advantages, such as public verification and decryption fairness, which are attractive for wireless network applications. Moreover, our scheme has the indistinguishability against adaptive chosen ciphertext attacks, the existential unforgeability against adaptive chosen messages attacks, and anonymous indistinguishability of encryptions under selective‐ID, chosen ciphertext attack in the random oracle model. Copyright © 2016 John Wiley & Sons, Ltd.

The Fujisaki-Okamoto (FO) conversion is a generic conversion to enhance a public key encryption scheme with security of one-way against chosen plaintext attacks (OW-CPA) to security of indistinguishable against adaptive chosen ciphertext attacks (IND-CCA) in the random oracle model. Existing works have shown that the FO conversion also can generically upgrade the security of the identity-based encryption (IBE) schemes or certificateless public key encryption (CL-PKE) schemes. However, it is still unknown if the same holds for certificate-based encryption (CBE) schemes. In this paper, we investigate the generic security of the CBE scheme obtained by applying the FO conversion to an arbitrary underlying OW-CBE-CPA secure CBE scheme and confirm that the FO conversion can generically convert any OW-CBE-CPA secure CBE into an IND-CBE-CCA secure CBE. We also note that the straightforward application of the FO conversion only leads to a CBE scheme with a loose reduction. To solve this problem, we propose an enhanced FO conversion which just introduces minor extra computation overhead, but results in considerably more efficient security reduction.

OAEP 3-Round is a famous padding scheme.But if the attacker could obtain the random string of the OAEP 3-Round,it would not be indistinguishable against adaptive chosen ciphertext attacks any more.Examples are given to support the argument.The authors improve the OAEP 3-Round padding scheme to be plaintext awareness and prove that the revised version is semantic security against adaptive chosen ciphertext attacks in the random oracle model even in the case that attacker could get the random string of the padding scheme.

According to most existing identity-based ring signcryption schemes are based on random oracle model and have too many pairings, a new efficient identity-based ring signcryption scheme is proposed. It can satisfy the unconditional anonymity of the sender by using symmetric encryption algorithm and reduce the pairings by skillfully setting public parameters. Its indistinguishability under adaptive chosen ciphertext attack is proofed by the intractability of the DBDH problem and the unforgeability under adaptive chosen message attack is proved by the intractability of the CDH problem.

Signcryption is a basic cryptographic primitive that simultaneously captures the functions of encryption and signature. To realize comprehensive information security against quantum computing attacks, lattice-based signcryption schemes have been successively proposed. However, the performance of signcryption schemes should be improved in the lattice setting. An efficient lattice-based signcryption scheme in the standard model is proposed in this paper. Under the ring learning with errors (RLWE) assumption and the ideal short integer solution (ISIS) assumption, the proposed signcryption scheme achieves indistinguishability against adaptive chosen ciphertext attacks (IND-CCA2) and existential unforgeability under an adaptive chosen-message attack (EUF-ACMA). Our scheme not only reduces the communication and computational overhead but also realizes a new design that combines the partitioning technique with the idea of tag-based key encapsulation. The performance analysis results show that our scheme is more efficient than previous lattice-based signcryption schemes in the standard model.

To achieve heterogeneous communication from certificateless cryptography (CLC) to identity-based cryptography (IBC), we present a heterogeneous scheme that enables m senders in the CLC to transmit m message to n receivers in the IBC. In the proposed signcryption scheme, each sender is mapped to a distinct pseudo identity, so the sender’s identity privacy preservation can be guaranteed. At the same time, to ensure the receiver’s identity privacy, the identity information of all authorized recipients is mixed by the Lagrange interpolation polynomial during the signcryption process, which prevents the receiver’s identity from being exposed. Compared with existing schemes, the proposed scheme presents efficient computational overhead and is suitable for heterogeneous environments. In addition, our scheme has the indistinguishability against adaptive chosen ciphertext attacks and existential unforgeability against adaptive chosen-message attacks in the random oracle model.

Quite recently, Tseng and Tsai proposed a revocable identity (ID)-based encryption (RIBE) with a public channel, in which the private key generator (PKG) can efficiently revoke misbehaving/compromised users by using a public channel. Considering the problem where a sender would like to encrypt an identical message for n receivers, the sender must re-encrypt the message n times using Tseng and Tsai’s RIBE scheme. In such a case, n expensive pairing operations are required for the re-encrypting procedure. In this paper, for reducing the pairing operations, we extend Tseng and Tsai’s RIBE to propose an efficient revocable multi-receiver ID-based encryption (RMIBE) scheme. Our scheme only needs one pairing operation to encrypt an identical message for n receivers while remaining the merit of user revocability in Tseng and Tsai’s RIBE scheme. We demonstrate that the RMIBE scheme is semantically secure against adaptive chosen ciphertext attacks (CCA) in the random oracle model.DOI: http://dx.doi.org/10.5755/j01.itc.42.2.2244

We define new algorithmic problems and discuss their properties (in particular, we present a careful study of their computational complexity). We apply the new problems to design public key encryption protocols with semantic security relative to their decisional variants. We then show how to provide efficient schemes that are semantically secure under adaptive chosen ciphertext attacks in the random oracle model. Finally, we show that the ideas developed in this extended abstract can be used to design the most efficient known cryptosystem with semantic security under non-adaptive chosen ciphertext attacks in the standard security model.

Attribute-based encryption (ABE) scheme has become an important technology in cryptography. However, the considerable overhead of encryption and decryption restricts its application on the devices with limited resource. Fortunately, as the development of cloud computing, someone presents that outsourcing decryption and encryption can be used to deal with the problem. This idea has drawn a lot of attention after being proposed. Recently, Li et al. put forward an efficient verifiable outsourced ABE scheme which outsources the encryption and decryption to the cloud server and enables its valid receivers to verify the correctness of the message after decrypting. However, in this paper, we prove that their scheme is not secure under chosen plaintext attack which is the basic security requirement of ABE scheme. Then, we improve their scheme and illustrate that the improved scheme is adaptive chosen ciphertext attack (CCA2) secure in the random oracle model. The final comparison shows that we do not add extra computational burden to improve the security.

Non-malleability is an important and intensively studied security notion for many cryptographic primitives. In the context of public key encryption, this notion means it is infeasible for an adversary to transform an encryption of some message m into one of a related message m' under the given public key. Although it has provided a strong security property for many applications, it still does not suffice for some scenarios like the system where the users could issue keys on-the-fly. In such settings, the adversary may have the power to transform the given public key and the ciphertext. To withstand such attacks, Fischlin introduced a stronger notion, known as complete non-malleability, which requires that the non-malleability property be preserved even for the adversaries attempting to produce a ciphertext of some related message under the transformed public key. To date, many schemes satisfying this stronger security have been proposed, but they are either inefficient or proved secure in the random oracle model. In this work, we put forward a new encryption scheme in the common reference string model. Based on the standard DBDH assumption, the proposed scheme is proved completely non-malleable secure against adaptive chosen ciphertext attacks in the standard model. In our scheme, the well-formed public keys and ciphertexts could be publicly recognized without drawing support from unwieldy techniques like non-interactive zero knowledge proofs or one-time signatures, thus achieving a better performance.

Notes on a provably-secure certificate-based encryption against malicious CA attacks

In order to keep the confidential data in the cloud against unauthorized parties, a cryptographic access control solution based on Attribute-Based Encryption (ABE) and Identity-Based Signature (IBS) is introduced in this paper. Under the premise that cloud service provider is untrustful, the proposed scheme can ensure the data security of the cloud storage system in an open environment, as well as reduce the complexity of management. Analysis and experimental results show that the scheme can be semantically secure against adaptive chosen ciphertext attacks under the random oracle model. Our concrete access control scheme can enhance the efficiency of the cloud to a certain extent.

Vehicular ad hoc networks (VANETs), an application of the Internet of Things (IoT) providing a better intelligent transportation system (ITS), has received substantial attention from both industry and academia. Heterogeneous vehicular communications in VANETs occur when both vehicles and the infrastructure use different cryptographic technologies to exchange safety messages. However, the safety messages between vehicles and the infrastructure are communicated wirelessly; therefore, security issues are a serious concern in this domain. The existing schemes secure the transmission of safety messages with respect to confidentiality, authentication, and nonrepudiation. However, they are inappropriate with respect to efficiency. They cause computational overhead on the receiver and bandwidth overhead in the communications. To cope with this, we propose an elliptic curve cryptosystem-based hybrid signcryption (ECCHSC) protocol that satisfies the security requirements (i.e., message confidentiality, message’s source authentication, message integrity, nonrepudiation, and identity–anonymity) for heterogeneous vehicle-to-infrastructure (V2I) communications in a single logical step. This protocol allows secure transmission of a safety message from a vehicle using identity-based cryptography (IDC) to a roadside unit (RSU) using public-key infrastructure (PKI). In addition, the ECCHSC protocol enables the RSU to receive multiple ciphertexts, aggregate them, and de-signcrypt them simultaneously through the batch de-signcryption method, which further improves the performance. The ECCHSC protocol has indistinguishability against adaptive chosen ciphertext attacks (IND-CCA2) and existential unforgeability against adaptive chosen message attacks (EUF-CMAs) in the random oracle model (ROM). The performance analysis of our protocol demonstrates a significant reduction in computational overhead and in communication/storage overhead as compared to the state-of-the-art schemes.

In this paper, we propose a new “full public verifiability” concept for hybrid public-key encryption schemes. We also present a new hybrid public-key encryption scheme that has this feature, which is based on the decisional bilinear Diffie-Hellman assumption. We have proven that the new hybrid public-key encryption scheme is secure against adaptive chosen ciphertext attack in the standard model. The “full public verifiability” feature means that the new scheme has a shorter ciphertext and reduces the security requirements of the symmetric encryption scheme. Therefore, our new scheme does not need any message authentication code, even when the one-time symmetric encryption scheme is passive attacks secure. Compared with all existing publickey encryption schemes that are secure to the adaptive chosen ciphertext attack, our new scheme has a shorter ciphertext, efficient tight security reduction, and fewer requirements (if the symmetric encryption scheme can resist passive attacks).