Signcryption

This paper proposes a new public key authenticated encryption (signcryption) scheme based on the hardness of q-Diffie-Hellman problems in Gap Diffie-Hellman groups. This new scheme is quite efficient: the signcryption operation has almost the same cost as an El Gamal encryption while the reverse operation only requires one pairing evaluation and three exponentiations. The scheme's chosen-ciphertext security is shown to be related to the hardness of the q-Diffie-Hellman Inversion (q−DHI) problem in the random oracle model while its unforgeability is proved under the q-Strong Diffie-Hellman assumption (q-SDH). It also provides detachable signatures that are unlinkable to the original anonymous ciphertext. We also show that most of the sender's workload can be computed offline. Our construction is based on a signature scheme independently studied by Boneh-Boyen and Zhang et al. in 2004.

We present an identity-based on-line/off-line signcryption scheme, where most of computations are carried out when the message is not available(i.e., off-line stage) and the on-line part of our scheme does not require any exponent computations and therefore is very efficient. It combines the functionalities of signature and encryption and is provably secure in the random oracle model. We also show that our scheme is indistinguishable against adaptive chosen-ciphertext attacks (IND-IDSC-CCA2) and is existentially unforgeable against adaptive chosen-message attacks (EF-IDSC-ACMA).

a day's information technology is a part of day to day's life. Everybody wants to store data in soft format in a central place so that it can be accessed any point of time. When a remote user tries accessing it through an unreliable network then data may not be secure. There are many techniques to secure data or message. Signcryption is one of the booming issues in the field of security. In 1997 Zheng introduce signcryption scheme by combining the techniques of digital signature then encryption in one step which reduces the computational cost and communication overhead (1). Signcryption also verifies the sender without reading content of the message by third party (10). Many researchers have given their signcryption scheme to achieve security goals like forward secrecy, like confidentiality, unforgeability, integrity, forward secrecy and public verification non repudiation but many of them having their own limitations (2, 8, 16). In this paper a novel signcryption scheme pro...

This article presents a new signcryption scheme which is based on the Schnorr digital signature algorithm. The new scheme represents my personal contribution to signcryption area. I have been implemented the algorithm in a program and here are provided the steps of the algorithm, the results and
some examples. The paper also contains the presentation of the original Signcryption scheme, based on ElGamal digital signature and discusses the practical applications of Signcryption in real life.

Signcryption is a cryptographic primitive that provides authentication and confidentiality simultaneously in a single logical step. It is often required that multiple senders have to signcrypt a single message to a certain receiver. Obviously, it is inefficient to signcrypt the messages separately. An efficient alternative is to go for multi-signcryption. The concept of multi-signcryption is similar to that of multi-signatures with the added property - confidentiality. Recently, Jianhong et al. proposed an identity based multi-signcryption scheme. They claimed that their scheme is secure against adaptive chosen ciphertext attack and it is existentially unforgeable. In this paper, we show that their scheme is not secure against chosen plaintext attack and is existentially forgeable, we also provide a fix for the scheme and prove formally that the improved scheme is secure against both adaptive chosen ciphertext attack and existential forgery.

The security of data become a major issue in the present days, there are different dimensions of security in this paper we will discuss one of the major properties of security. The signcryption is one of the techniques to secure your data by encrypting it. It was first introduced by Zheng in 1997 based on DLP. The signcryption combines the techniques of digital signature and encryption which reduces computational cost and communication overhead. The Signcryption scheme verifies the integrity of message before decryption of cipher text it also provides how the message can be verify by third party without reading the content of message. Many researchers have given their signcryption scheme to achieve security goals like confidentiality, unforgeability, integrity, forward secrecy and public verification every scheme is having their own limitations. This paper represents the cryptanalysis of popular signcryption scheme in terms of major security goals alpng with the communication overhead and computational cost.

Electronic commerce, as exemplified by the popularity of the Internet, is becoming more important along
with fast progress in communications and information technology. The SET (Secure Electronic
Transaction) protocol is a scheme designed to ensure that merchants and cardholders can conduct business
over a public network. Although the SET protocol has some disadvantages, but still it is the most commonly
used protocol in the Internet shopping. Signcryption is a cryptographic primitive which simultaneously
provides both confidentiality and authenticity in a single logical step. Signcryption based on elliptic curves
provides the same level of security using smaller keys compared to schemes based on the discrete logarithm
problem over finite fields. This paper examines the benefits of using signcryption rather than signaturethen-encryption
in the SET protocol. Using identity-based signcryption in the SET protocol reduces the
number of encryption and decryption operations. Moreover, signcryption is less time consuming than
signature-then-encryption.

The certificate-based cryptosystems is traditional way in providing the system parameters. Identity-based
cryptography is more efficient than certificate-based cryptosystems. Each user in identity-based
cryptography uses any arbitrary string that uniquely identifies him as his public key. This paper proposes
a new identity-based tripartite signcryption scheme based on the elliptic curve discrete logarithm problem.
The proposed id-based tripartite signcryption scheme does not use the bilinear pairings in both the
Signcryption and unsigncryption phases. The proposed scheme used to reduce the communication over
head when three entities wants to communicate securely as in authentication protocol in GSM and in ecommerce.
The proposed scheme satisfies various desirable security properties. Also, the performance of
the proposed scheme is tested.

Hyper elliptical curve cryptography is the prominent public key encrypto systems with practical approach to high level of security and shorter bit size of encryption. Public key encryption is a reliable cryptographic method for mobile adhoc networks. Still, some shortcomings of key management deter the reputation of its utilization in the real-time environment. One major disadvantage in the crucial necessity of elucidation is the key escrow problem. For secure group-based data transmission in the distributed environment, a secret key has to be shared among the users for the secured data transmission. For establishing efficient key distribution and management, a novel dynamic group secret key management is introduced. In this paper, we propose a signcryption based hyper elliptic curve cryptography framework for key escrow. Here the model of scheme is to divide a large group into several subgroups, each maintaining its subgroup secret keys to control the subgroup and managing many subgroups using Key Escrow Based Hyper Elliptic Curve Cryptography management algorithm. In the paper, a new methodology for collaborative key management using signcryption is implemented. The environment for mobile networks with the proposed algorithm named signcryption based Key Escrow HECC for Signcryption (KEHECCS) with a comparison of the conventional algorithms prevailing for MANETs is simulated. Compared to the existing approaches, KEHECCS demonstrates advanced key distribution features with better throughput efficiency without compromising on communication overhead and storage cost

Signcryption simultaneously offers authentication through unforgeability and confidentiality through indistinguishability against chosen ciphertext attacks by combining the functionality of digital signatures and public-key encryption into a single operation. Libert and Quisquater (PKC 2004) extended this set of basic requirements with the notions of ciphertext anonymity (or key privacy) and key invisibility to protect the identities of signcryption users and were able to prove that key invisibility implies ciphertext anonymity by imposing certain conditions on the underlying signcryption scheme. This paper revisits the relationship amongst privacy notions for signcryption. We prove that key invisibility implies ciphertext anonymity without any additional restrictions. More surprisingly, we prove that key invisibility also implies indistinguishability against chosen ciphertext attacks. This places key invisibility on the top of privacy hierarchy for public-key signcryption schemes.

Signcryption as a single cryptographic primitive offers both confidentiality and authentication simultaneously. Generally in signcryption schemes, the message is hidden and thus the validity of the ciphertext can be verified only after unsigncrypting the ciphertext. Thus, a third party will not be able to verify whether the ciphertext is valid or not. Signcryption schemes that allow any user to verify the validity of the ciphertext without the knowledge of the message are called public verifiable signcryption schemes. Third Party verifiable signcryption schemes allow the receiver to convince a third party, by providing some additional information along with the signcryption other than his private key with/without exposing the message.

Chaos is one type of complex dynamic behaviour generated by determined nonlinear dynamic systems.Chaos functions have mainly used to develop mathematical models of non linear systems .Chaotic systems have many important properties, such as sensitive dependence on initial conditions, system parameters, density of point set topology of all cycles passed. Most properties such as mixing and diffusion are related to some requirement in the sense of cryptography. Therefore, provide more useful and practical applications of chaotic cryptosystems. In this paper, we investigate the utility of such functions in signcryption scheme for secure communication. An algorithm using a simple chaotic function f(x) = 3*x *(1 -x 2 ) is proposed .The proposed scheme is highly sensitive to the initial conditions. This paper presents chaos based Multi message signcryption scheme with public verifiability concept. The proposed scheme works for both single recipient and multiple recipients. The proposed scheme uses a chaos based multi key generator to generate multiple keys for signcryption scheme, and provides high security due to its chaotic nature. This represents important improvements over the chaotic key multi-message multi-recipient signcryption (CPK-MM-MRS) scheme proposed earlier.

A key encapsulation mechanism (KEM) that takes as input an arbitrary string, i.e., a tag, is known as tag-KEM, while a scheme that combines signature and encryption is called signcryption. In this paper, we present a code-based signcryption tag-KEM scheme. We utilize a code-based signature and a CCA2 (adaptive chosen ciphertext attack) secure version of McEliece's {encryption} scheme. The proposed scheme uses an equivalent subcode as a public code for the receiver, making the NP-completeness of the equivalent subcode problem be one of our main security assumptions. We then base the signcryption tag-KEM to design a code-based hybrid signcryption scheme. A hybrid scheme deploys an asymmetric- as well as a symmetric-key encryption. We give security analyses of both our schemes in the standard model and prove that they are secure against IND-CCA2 (indistinguishability under adaptive chosen ciphertext attack) and SUF-CMA (strong existential unforgeability under chosen message attack).

a day's information technology is a part of day to day's life. Everybody wants to store data in soft format in a central place so that it can be accessed any point of time. When a remote user tries accessing it through an unreliable network then data may not be secure. There are many techniques to secure data or message. Signcryption is one of the booming issues in the field of security. In 1997 Zheng introduce signcryption scheme by combining the techniques of digital signature then encryption in one step which reduces the computational cost and communication overhead (1). Signcryption also verifies the sender without reading content of the message by third party (10). Many researchers have given their signcryption scheme to achieve security goals like forward secrecy, like confidentiality, unforgeability, integrity, forward secrecy and public verification non repudiation but many of them having their own limitations (2, 8, 16). In this paper a novel signcryption scheme pro...

Most of the existing hierarchical secret-sharing schemes are unconditionally (non-cryptographically) secured, and they cannot survive from various types of attacks especially when the participants use resource-constrained wireless mobile devices. In our proposed ...

Natural and man-made catastrophic events appear be steadily increasing in intensity and frequency. Proper preparation, response and recovery are essential if mankind and its vital systems are to cope with and survive large-scale disasters. Unfortunately, on account of historical and geographical reasons, the organisations responsible for delivering emergency response services often under-perform (or even fail), typically due to a lack of proper interoperation and collaboration. This paper attempts to analyse interoperability issues specific to disaster management and propose a way forward based on the advances in interoperability research, using an enterprise integration and architecture perspective in order to ensure a holistic approach.

This article proposes a hybrid certificateless signcryption scheme that is secure against adaptive chosen ciphertext adversary in the random oracle model. The scheme combines an asymmetric encryption which is one way against chosen plaintext attack and any One-Time secure symmetric encryption scheme, combined using Fujisaki–Okamoto transformation. Uncommon to many Fujisaki–Okamoto based constructions which ensure message integrity alone, this scheme provides entity authentication in addition. By the choice of a hash function that utilizes the advantage of sponge based construction, the scheme enables the user to incorporate any One-Time secure symmetric encryption by re-configuring the input/output parameters. Fujisaki–Okamoto transformation, which is currently a standard in hybrid constructions, guarantees the indistinguishability against adaptive chosen ciphertext attack. The provision for choosing symmetric encryption in the scheme enables it to be implemented in all sort of cryptographic requirements including those in wireless communication.

An Identity-based cryptosystem is a Public Key cryptosystem in which the public keys of the entities are their identities, or strings derived from their identities. Signcryption combines digital signatures and encryption with a cost significantly smaller than that required for signature-thenencryption. This paper proposes an ID-based signcryption scheme based on bilinear pairings on elliptic curves. It is shown that the new scheme is an improved version of the existing signcryption scheme [10] by comparing the computations in both the schemes.

Mobile communication and Mobile Commerce is most famous nowadays as a result of the administration offered amid the portability. In any case, notwithstanding of its new headways, versatile correspondence has been confronting numerous security issues. This paper looked into different security systems dependent on the cryptographic methods. This paper mostly centers the Signcryption based cryptographic strategy, since Signcryption has been appeared to be valuable in different applications, for example, electronic trade, versatile correspondences, and smart cards. At last this paper gives the proposed research philosophy configuration to be executed in the future.

... Dr Faisal Bashir Computer Science Dept College of Telecommunication Engineering (MCS) Rawalpindi, Pakistan [email protected] Dr Asif Masood Computer Science Dept College of Telecommunication Engineering (MCS) Rawalpindi, Pakistan [email protected] ...

Security of mobile communications comes with the cost of computational overhead. Reducing the overhead in security computations is critical to ensure the overall performance of a mobile network. In this paper, we present the notion of online/offline signcryption, where most of computations are carried out offline and the online part of our scheme does not require any exponent computations and therefore is very efficient. Our scheme allows any third party to verify the encryption without compromising confidentiality. We also show that our scheme is secure against existential forgery under chosen message attacks and adaptively chosen ciphertext attacks under the notion of indistinguishability of ciphertext.

Cloud computing is a computing paradigm that involves outsourcing of computing resources with the capabilities of expendable resource scalability, on-demand provisioning with little or no up-front IT infrastructure investment costs. It has recently emerged as a promising hosting platform that performs an intelligent usage of a collection of services, applications, information and infrastructure comprised of pools of computer, network, information and storage resources. However along with these advantages, storing a large amount of data including critical information on the cloud motivates highly skilled hackers thus creating a need for the security to be considered as one of the top issues while considering Cloud Computing. In the cloud storage model, data is stored on multiple virtualized servers. Physically the resources will span multiple servers and can even span storage sites. We have proposed an effective scheme to ensure the correctness of user's data on cloud data storage and public verifiability without demanding user's time, feasibility or resources. Whenever data corruption is detected during the storage correctness verification, this scheme can almost guarantee the simultaneous localization of data errors and the identification of the misbehaving server(s).