On the Security of ID Based Signcryption Schemes

A signcryption scheme is secure only if it satisfies both the confidentiality and the unforgeability properties. All the ID based signcryption schemes presented in the standard model till now do not have either the confidentiality or the unforgeability or both of these properties. Cryptanalysis of some of the schemes have been proposed already. In this work, we present the security attacks on `Secure ID based signcryption in the standard model\u27 proposed by Li-Takagi and `Further improvement of an identity-based signcryption scheme in the standard model\u27 by Li et al. and the flaws in the proof of security of `Efficient ID based signcryption in the standard model\u27 proposed by Li et al., which are the recently proposed ID based signcryption schemes in the standard model. We also present the cryptanalysis of `Construction of identity based signcryption schemes\u27 proposed by Pandey-Barua and the cryptanalysis of `Identity-Based Signcryption from Identity-Based Cryptography\u27 proposed by Lee-Seo-Lee. These schemes present the methods of constructing an ID based signcryption scheme in the random oracle model from an ID based signature scheme and an ID based encryption scheme. Since none of the existing schemes in the standard model are found to be provably secure, we analyse the security of signcryption schemes got by directly combining an ID based signature scheme and an ID based encryption scheme in the standard model

SIGNCRYPTION ANALYZE

The aim of this paper is to provide an overview for the research that has been done so far in signcryption area. The paper also presents the extensions for the signcryption scheme and discusses the security in signcryption. The main contribution to this paper represents the implementation of the signcryption algorithm with the examples provided.ElGamal, elliptic curves, encryption, identity-based, proxy-signcryption, public key, ring-signcryption, RSA, signcryption

An Efficient identity based Multi-receiver Signcryption Scheme using ECC

ABSTRACT Signcryption is a technique of performing signature and encryption in a single logical step. It is a secure and efficient technique of providing security between the sender and the receiver so that the data send by the sender should be made secure from various types of attacks such as desynchronization attacks, identity disclosure attack and spoofing attacks. Although there are many technique implemented for the generation of signature and encryption. Here a new and efficient technique of signcryption has been implemented in a multireceiver environment on the basis of identity of the receiver. The proposed work given here is the implementation of signcryption scheme using elliptic curve cryptography where the authentication between sender and the receiver is based on the identity of the receiver

CGST: Provably Secure Lightweight Certificateless Group Signcryption Technique Based on Fractional Chaotic Maps

In recent years, there has been a lot of research interest in analyzing chaotic constructions and their associated cryptographic structures. Compared with the essential combination of encryption and signature, the signcryption scheme has a more realistic solution for achieving message confidentiality and authentication simultaneously. However, the security of a signcryption scheme is questionable when deployed in modern safety-critical systems, especially as billions of sensitive user information is transmitted over open communication channels. In order to address this problem, a lightweight, provably secure certificateless technique that uses Fractional Chaotic Maps (FCM) for group-oriented signcryption (CGST) is proposed. The main feature of the CGST-FCM technique is that any group signcrypter may encrypt data/information with the group manager (GM) and have it sent to the verifier seamlessly. This implies the legitimacy of the signcrypted information/data is verifiable using the public conditions of the group, but they cannot link it to the conforming signcrypter. In this scenario, valid signcrypted information/data cannot be produced by the GM or any signcrypter in that category alone. However, the GM is allowed to reveal the identity of the signcrypter when there is a legal conflict to restrict repudiation of the signature. Generally, the CGST-FCM technique is protected from the indistinguishably chosen ciphertext attack (IND-CCA). Additionally, the computationally difficult Diffie-Hellman (DH) problems have been used to build unlinkability, untraceability, unforgeability, and robustness of the projected CGST-FCM scheme. Finally, the security investigation of the presented CGST-FCM technique shows appreciable consistency and high efficiency when applied in real-time security applications

Studies on the Security of Selected Advanced Asymmetric Cryptographic Primitives

The main goal of asymmetric cryptography is to provide confidential communication, which allows two parties to communicate securely even in the presence of adversaries. Ever since its invention in the seventies, asymmetric cryptography has been improved and developed further, and a formal security framework has been established around it. This framework includes different security goals, attack models, and security notions. As progress was made in the field, more advanced asymmetric cryptographic primitives were proposed, with other properties in addition to confidentiality. These new primitives also have their own definitions and notions of security. This thesis consists of two parts, where the first relates to the security of fully homomorphic encryption and related primitives. The second part presents a novel cryptographic primitive, and defines what security goals the primitive should achieve. The first part of the thesis consists of Article I, II, and III, which all pertain to the security of homomorphic encryption schemes in one respect or another. Article I demonstrates that a particular fully homomorphic encryption scheme is insecure in the sense that an adversary with access only to the public material can recover the secret key. It is also shown that this insecurity mainly stems from the operations necessary to make the scheme fully homomorphic. Article II presents an adaptive key recovery attack on a leveled homomorphic encryption scheme. The scheme in question claimed to withstand precisely such attacks, and was the only scheme of its kind to do so at the time. This part of the thesis culminates with Article III, which is an overview article on the IND-CCA1 security of all acknowledged homomorphic encryption schemes. The second part of the thesis consists of Article IV, which presents Vetted Encryption (VE), a novel asymmetric cryptographic primitive. The primitive is designed to allow a recipient to vet who may send them messages, by setting up a public filter with a public verification key, and providing each vetted sender with their own encryption key. There are three different variants of VE, based on whether the sender is identifiable to the filter and/or the recipient. Security definitions, general constructions and comparisons to already existing cryptographic primitives are provided for all three variants.Doktorgradsavhandlin

An efficient FIS and RSA based Signcryption Security Scheme

No Abstrac

Identity based signcryption schemes without random oracles

Signcryption is a cryptographic primitive which performs encryption and signature in a single logical step with the cost lower than signature-then-encryption approach.. In this paper we gave attacks on confidentiality and unforgeability of two identity based signcryption schemes without random oracles. Further we proposed an improved identity based signcryption scheme without random oracles. We also proposed an identity based public verifiable signcryption scheme with third party verification without random oracles