Biblio

Group signatures are a central tool in privacy-enhancing cryptography, which allow members of a group to anonymously produce signatures on behalf of the group. Consequently, they are an attractive means to implement privacy-friendly authentication mechanisms. Ideally, group signatures are dynamic and thus allow to dynamically and concurrently enroll new members to a group. For such schemes, Bellare et al. (CT-RSA»05) proposed the currently strongest security model (BSZ model). This model, in particular, ensures desirable anonymity guarantees. Given the prevalence of the resource asymmetry in current computing scenarios, i.e., a multitude of (highly) resource-constrained devices are communicating with powerful (cloud-powered) services, it is of utmost importance to have group signatures that are highly-efficient and can be deployed in such scenarios. Satisfying these requirements in particular means that the signing (client) operations are lightweight. We propose a novel, generic approach to construct dynamic group signature schemes, being provably secure in the BSZ model and particularly suitable for resource-constrained devices. Our results are interesting for various reasons: We can prove our construction secure without requiring random oracles. Moreover, when opting for an instantiation in the random oracle model (ROM) the so obtained scheme is extremely efficient and outperforms the fastest constructions providing anonymity in the BSZ model - which also rely on the ROM - known to date. Regarding constructions providing a weaker anonymity notion than BSZ, we surprisingly outperform the popular short BBS group signature scheme (CRYPTO»04; also proven secure in the ROM) and thereby even obtain shorter signatures. We provide a rigorous comparison with existing schemes that highlights the benefits of our scheme. On a more theoretical side, we provide the first construction following the "without encryption" paradigm introduced by Bichsel et al. (SCN»10) in the strong BSZ model.

Internet of Things (IoT) device authentication is weighed as a very important step from security perspective. Privacy and security of the IoT devices and applications is the major issue. From security perspective, important issue that needs to be addressed is the authentication mechanism, it has to be secure from different types of attacks and is easy to implement. The paper gives general idea about how different authentication mechanisms work, and then secure and efficient multi-factor device authentication scheme idea is proposed. The proposed scheme idea uses digital signatures and device capability to authenticate a device. In the proposed scheme device will only be allowed into the network if it is successfully authenticated through multi-factor authentication otherwise the authentication process fails and whole authentication process will restart. By analyzing the proposed scheme idea, it can be seen that the scheme is efficient and has less over head. The scheme not only authenticates the device very efficiently through multi-factor authentication but also authenticates the authentication server with the help of digital signatures. The proposed scheme also mitigates the common attacks like replay and man in the middle because of nonce and timestamp.

The complete digitization of telecommunications allows new attack scenarios, which have not been possible with legacy phone technologies before. The reason is that physical access to legacy phone technologies was necessary. Regarding internet-based communication like voice over the internet protocol (VoIP), which can be established between random nodes, eavesdropping can happen everywhere and much easier. Additionally, injection of undesirable communication like SPAM or SPIT in digital networks is simpler, too. Encryption is not sufficient because it is also necessary to know which participants are talking to each other. For that reason, the research project INTEGER has been started with the main goals of providing secure authentication and integrity of a VoIP communication by using a digital signature. The basis of this approach is the Trusted Platform Module (TPM) of the Trusted Computing Group (TCG) which works as a hardware-based trusted anchor. The TPM will be used inside of wireless IP devices with VoIP softphones. The question is if it is possible to fulfill the main goals of the project in wireless scenarios with Wi-Fi technologies. That is what this contribution aims to clarify.

The RSA PKCS\#1 v1.5 signature algorithm is the most widely used digital signature scheme in practice. Its two main strengths are its extreme simplicity, which makes it very easy to implement, and that verification of signatures is significantly faster than for DSA or ECDSA. Despite the huge practical importance of RSA PKCS\#1 v1.5 signatures, providing formal evidence for their security based on plausible cryptographic hardness assumptions has turned out to be very difficult. Therefore the most recent version of PKCS\#1 (RFC 8017) even recommends a replacement the more complex and less efficient scheme RSA-PSS, as it is provably secure and therefore considered more robust. The main obstacle is that RSA PKCS\#1 v1.5 signatures use a deterministic padding scheme, which makes standard proof techniques not applicable. We introduce a new technique that enables the first security proof for RSA-PKCS\#1 v1.5 signatures. We prove full existential unforgeability against adaptive chosen-message attacks (EUF-CMA) under the standard RSA assumption. Furthermore, we give a tight proof under the Phi-Hiding assumption. These proofs are in the random oracle model and the parameters deviate slightly from the standard use, because we require a larger output length of the hash function. However, we also show how RSA-PKCS\#1 v1.5 signatures can be instantiated in practice such that our security proofs apply. In order to draw a more complete picture of the precise security of RSA PKCS\#1 v1.5 signatures, we also give security proofs in the standard model, but with respect to weaker attacker models (key-only attacks) and based on known complexity assumptions. The main conclusion of our work is that from a provable security perspective RSA PKCS\#1 v1.5 can be safely used, if the output length of the hash function is chosen appropriately.

In past, several Certificate Authority (CA) compromise and subsequent mis-issue of certificate raise the importance of certificate transparency and dynamic trust management for certificates. Certificate Transparency (CT) provides transparency for issued certificates, thus enabling corrective measure for a mis-issued certificate by a CA. However, CT and existing mechanisms cannot convey the dynamic trust state for a certificate. To address this weakness, we propose Smart Contract-assisted PKI (SCP) - a smart contract based PKI extension - to manage dynamic trust network for PKI. SCP enables distributed trust in PKI, provides a protocol for managing dynamic trust, assures trust state of a certificate, and provides a better trust experience for end-users.

Digital signature over elliptic curve is one of the most important applications of security because it is effective. Recently, it has been developed and defined in the various standard of security. The application of the digital signature are signer authentication, data integrity, and non-repudiation. Currently, the requirements to implement authentication process on a computer hardware with limited resource such as energy, memory and computing power are increasing. The developer should consider these factors along with security factor for the effective implement on the computer hardware with limited resource. In this paper, we propose the Schnorr signature scheme using Koblitz curve over a field of characteristic two. The advantage of Schnorr signature scheme is a good combination with Koblitz curve over a field of characteristic two, therefore its arithmetic can be performed in any computer. Moreover, we use Double-and-Add scalar multiplication to reduce time in the process of systems. In addition, this paper shows a result of time in the process of the system to compare the performance of the Schnorr signature scheme on Koblitz curve using Double-andAdd scalar multiplication with the Schnorr signature scheme on Koblitz curve using typical scalar multiplication. The result of this study is that both systems working correctly. However, the Schnorr signature scheme on Koblitz curve using Double-andAdd performs better in time efficiency than of Schnorr signature scheme on Koblitz curve using typical scalar multiplication.

This research proposes a system for detecting known and unknown Distributed Denial of Service (DDoS) Attacks. The proposed system applies two different intrusion detection approaches anomaly-based distributed artificial neural networks(ANNs) and signature-based approach. The Amazon public cloud was used for running Spark as the fast cluster engine with varying cores of machines. The experiment results achieved the highest detection accuracy and detection rate comparing to signature based or neural networks-based approach.

We consider a generic model of Client-Server interactions in the presence of Sender and Relay, conceptual agents acting on behalf of Client and Server, respectively, and modeling cloud service providers in the envisaged "QoS as a Service paradigm". Client generates objects which Sender tags with demanded QoS level, whereas Relay assigns the QoS level to be provided at Server. To verify an object's right to a QoS level, Relay detects its signature that neither Client nor Sender can modify. Since signature detection is costly, Relay tends to occasionally skip it and trust an object; this prompts Sender to occasionally launch a Fake VIP attack, i.e., demand undue QoS level. In a Stackelberg game setting, Relay employs a trust strategy in the form of a double-blind reputation scheme so as to minimize the signature detection cost and undue QoS provision, anticipating a best-response Fake VIP attack strategy on the part of Sender. We ask whether the double-blind reputation scheme, previously proved resilient to a probabilistic Fake VIP attack strategy, is equally resilient to more intelligent Sender behavior. Two intelligent attack strategies are proposed and analyzed using two-dimensional Markov chains.

Malicious software or malware is one of the most significant dangers facing the Internet today. In the fight against malware, users depend on anti-malware and anti-virus products to proactively detect threats before damage is done. Those products rely on static signatures obtained through malware analysis. Unfortunately, malware authors are always one step ahead in avoiding detection. This research deals with dynamic malware analysis, which emphasizes on: how the malware will behave after execution, what changes to the operating system, registry and network communication take place. Dynamic analysis opens up the doors for automatic generation of anomaly and active signatures based on the new malware's behavior. The research includes a design of honeypot to capture new malware and a complete dynamic analysis laboratory setting. We propose a standard analysis methodology by preparing the analysis tools, then running the malicious samples in a controlled environment to investigate their behavior. We analyze 173 recent Phishing emails and 45 SPIM messages in search for potentially new malwares, we present two malware samples and their comprehensive dynamic analysis.

A threshold signature scheme enables distributed signing among n players such that any subgroup of size \$t+1\$ can sign, whereas any group with t or fewer players cannot. While there exist previous threshold schemes for the ECDSA signature scheme, we are the first protocol that supports multiparty signatures for any \$t łeq n\$ with an efficient dealerless key generation. Our protocol is faster than previous solutions and significantly reduces the communication complexity as well. We prove our scheme secure against malicious adversaries with a dishonest majority. We implemented our protocol, demonstrating its efficiency and suitability to be deployed in practice.

We report on our implementation of a new Gaussian sampling algorithm for lattice trapdoors. Lattice trapdoors are used in a wide array of lattice-based cryptographic schemes including digital signatures, attributed-based encryption, program obfuscation and others. Our implementation provides Gaussian sampling for trapdoor lattices with prime moduli, and supports both single- and multi-threaded execution. We experimentally evaluate our implementation through its use in the GPV hash-and-sign digital signature scheme as a benchmark. We compare our design and implementation with prior work reported in the literature. The evaluation shows that our implementation 1) has smaller space requirements and faster runtime, 2) does not require multi-precision floating-point arithmetic, and 3) can be used for a broader range of cryptographic primitives than previous implementations.

The paper deals with the implementation aspects of the bilinear pairing operation over an elliptic curve on constrained devices, such as smart cards, embedded devices, smart meters and similar devices. Although cryptographic constructions, such as group signatures, anonymous credentials or identity-based encryption schemes, often rely on the pairing operation, the implementation of such schemes into practical applications is not straightforward, in fact, it may become very difficult. In this paper, we show that the implementation is difficult not only due to the high computational complexity, but also due to the lack of cryptographic libraries and programming interfaces. In particular, we show how difficult it is to implement pairing-based schemes on constrained devices and show the performance of various libraries on different platforms. Furthermore, we show the performance estimates of fundamental cryptographic constructions, the group signatures. The purpose of this paper is to reduce the gap between the cryptographic designers and developers and give performance results that can be used for the estimation of the implementability and performance of novel, upcoming schemes.

Digital signatures are replacing paper-based work to make life easier for customers and employees in various industries. We rigorously use RSA and Elliptic Curve Cryptography (ECC) for public key cryptographic algorithms. Nowadays ECDSA (Elliptical Curve Digital Signature Algorithm) gaining more popularity than the RSA algorithm because of the better performance of ECDSA over RSA. The main advantage of ECC over RSA is ECC provides the same level of security with less key size and overhead than RSA. This paper focuses on a brief review of the performance of ECDSA and RSA in various aspects like time, security and power. This review tells us about why ECC has become the latest trend in the present cryptographic scenario.

We would like to compute RSA signatures with the help of a Hardware Security Module (HSM). But what can we do when we want to use a certain public exponent that the HSM does not allow or support? Surprisingly, this scenario comes up in real-world settings such as code-signing of Intel SGX enclaves. Intel SGX enclaves have to be signed in order to execute in release mode, using 3072-bit RSA signature scheme with a particular public exponent. However, we encountered commercial hardware security modules that do not support storing RSA keys corresponding to this exponent. We ask whether it is possible to overcome such a limitation of an HSM and answer it in the affirmative (under stated assumptions). We show how to convert RSA signatures corresponding to one public exponent, to valid RSA signatures corresponding to another exponent. We define security and show that it is not compromised by the additional public knowledge available to an adversary in this setting.

Public key cryptography or asymmetric keys are widely used in the implementation of data security on information and communication systems. The RSA algorithm (Rivest, Shamir, and Adleman) is one of the most popular and widely used public key cryptography because of its less complexity. RSA has two main functions namely the process of encryption and decryption process. Digital Signature Algorithm (DSA) is a digital signature algorithm that serves as the standard of Digital Signature Standard (DSS). DSA is also included in the public key cryptography system. DSA has two main functions of creating digital signatures and checking the validity of digital signatures. In this paper, the authors compare the computational times of RSA and DSA with some bits and choose which bits are better used. Then combine both RSA and DSA algorithms to improve data security. From the simulation results, the authors chose RSA 1024 for the encryption process and added digital signatures using DSA 512, so the messages sent are not only encrypted but also have digital signatures for the data authentication process.

The communication security issue is of great importance and should not be ignored in backbone optical networks which is undergoing the evolution toward software defined networks (SDN). With the aim to solve this problem, this paper conducts deep analysis into the security challenge of software defined optical networks (SDON) and proposes a so-called security-enhanced signaling scheme of SDON. The proposed scheme makes full advantage of current OpenFIow protocol with some necessary extensions and security improvement, by combining digital signatures and message feedback with efficient PKI (Public Key Infrastructure) in signaling procedure of OpenFIow interaction. Thus, this security-enhanced signaling procedure is also designed in details to make sure the end-to-end trusted service connection. Simulation results show that this proposed approach can greatly improve the security level of large-scale optical network for Energy Internet services with better performance in term of connection success rate performance.

Bitcoin provides freshness properties by forming a blockchain where each block is associated with its timestamp and the previous block. Due to these properties, the Bitcoin protocol is being used as a decentralized, trusted, and secure timestamping service. Although Bitcoin participants which create new blocks cannot modify their order, they can manipulate timestamps almost undetected. This undermines the Bitcoin protocol as a reliable timestamping service. In particular, a newcomer that synchronizes the entire blockchain has a little guarantee about timestamps of all blocks. In this paper, we present a simple yet powerful mechanism that increases the reliability of Bitcoin timestamps. Our protocol can provide evidence that a block was created within a certain time range. The protocol is efficient, backward compatible, and surprisingly, currently deployed SSL/TLS servers can act as reference time sources. The protocol has many applications and can be used for detecting various attacks against the Bitcoin protocol.

The use of technology is increasing nowadays. On the other hand, most governments and legal offices still do not use technology to implement simple things such as signing a document because they still rely on face-to-face to ensure the authenticity of the signatory. Several challenges may come while signing documents online such as, how to authenticate the signing parties and how to ensure that signing parties will not deny their signatures in future? These challenges are addressed by SecureSign system that attach the signatories' identity with their fingerprints. SecureSign was implemented in C\# and Microsoft SQL Server Management Studio, with integrating fingerprint reader and electronic signature tablet. The SecureSign system achieves the main security goals which are confidentiality, authentication, non-repudiation and integrity. It will have an impact on society and business environments positively as it will reduce fraud and forgery, and help in controlling the process of signing either in contracts or confidential papers. SecureSign have Successfully achieved confidentiality by encrypting data using AES algorithm, authentication by using user fingerprint, nonrepudiation by associating the user ID with his fingerprint, and integrity by embedding QR barcode within the document and hashing its content.

Information security has become a major challenge in data transmission. Data transmitted through the network is vulnerable to many passive and active attacks. Cryptographic algorithms provide security against the data intruders and provide secure network communication. In this method, two algorithms TEA and DNA are combined to form a new algorithm called DETD (Double Encryption using TEA and DNA). The algorithm mainly deals with encryption and decryption time of a given input text. Here, both the encryption and decryption time are compared with the other two algorithms and the results are recorded. This algorithm also aims to provide data security by increasing the levels of encryption.

People use their personal computers, laptops, tablets and smart phones to digitally sign documents in company's websites and other online electronic applications, and one of the main cybersecurity challenges in this process is trusted digital signature. While the majority of systems use password-based authentication to secure electronic signature, some more critical systems use USB token and smart card to prevent identity theft and implement the trusted digital signing process. Even though smart card provides stronger security, any weakness in the terminal itself can compromise the security of smart card. In this paper, we investigate current smart card digital signature, and illustrate well-known basic vulnerabilities of smart card terminal with the real implementation of two possible attacks including PIN sniffing and message alteration just before signing. As we focus on second attack in this paper, we propose a novel mechanism using time-based digital signing by smart card to defend against message alteration attack. Our prototype implementation and performance analysis illustrate that our proposed mechanism is feasible and provides stronger security. Our method uses popular timestamping protocol packets and does not require any new key distribution and certificate issuance.

A key exchange protocol is an important primitive in the field of information and network security and is used to exchange a common secret key among various parties. A number of key exchange protocols exist in the literature and most of them are based on the Diffie-Hellman (DH) problem. But, these DH type protocols cannot resist to the modern computing technologies like quantum computing, grid computing etc. Therefore, a more powerful non-DH type key exchange protocol is required which could resist the quantum and exponential attacks. In the year 2013, Lei and Liao, thus proposed a lattice-based key exchange protocol. Their protocol was related to the NTRU-ENCRYPT and NTRU-SIGN and so, was referred as NTRU-KE. In this paper, we identify that NTRU-KE lacks the authentication mechanism and suffers from the man-in-the-middle (MITM) attack. This attack may lead to the forging the authenticated users and exchanging the wrong key.

Internet of things era grown very rapidly in Industrial Revolution 4.0, there are many researchers use the Wireless Sensor Network (WSN) technology to obtain the data for environmental monitoring. The data obtained from WSN will be sent to the Data Center, where users can view and collect all of data from the Data Center using end devices such as personal computer, laptop, and mobile phone. The Data Center would be very dangerous, because everyone can intercept, track and even modify the data. Security requirement to ensure the confidentiality all of stored data in the data center and give the authenticity in data has not changed during the collection process. Ciphertext Policy Attribute-Based Encryption (CP-ABE) can become a solution to secure the confidentiality for all of data. Only users with appropriate rule of policy can get the original data. To guarantee there is no changes during the collection process of the data then require the time stamp digital signature for securing the data integrity. To protect the confidentiality and data integrity, we propose a security mechanism using CP-ABE with user revocation and Time Stamp Digital Signature using Elliptic Curve Cryptography (ECC) 384 bits. Our system can do the revocation for the users who did the illegal access. Our system is not only securing the data but also providing the guarantee that is no changes during the collection process of the data from the Data Center.

Secure logging as an indispensable part of any secure system in practice is well-understood by both academia and industry. However, providing security for audit logs on an untrusted machine in a large distributed system is still a challenging task. The emergence and wide availability of log management tools prompted plenty of work in the security community that allows clients or auditors to verify integrity of the log data. Most recent solutions to this problem focus on the space-efficiency or public verifiability of forward security. Unfortunately, existing secure audit logging schemes have significant performance limitations that make them impractical for realtime large-scale distributed applications: Existing cryptographic hashing is computationally expensive for logging in task intensive or resource-constrained systems especially to prove individual log events, while Merkle-tree approach has fundamental limitations when face with highly concurrent, large-scale log streams due to its serially appending feature. The verification step of Merkle-tree based approach requiring a logarithmic number of hash computations is becoming a bottleneck to improve the overall performance. There is a huge gap between the flux of log streams collected and the computational efficiency of integrity verification in the large-scale distributed systems. In this work, we develop a novel scheme, performance of which favorably compares with the existing solutions. The performance guarantees that we achieve stem from a novel data structure called concurrent authenticated tree, which allows log events concurrently appending and removes the need to wait for append operations to complete sequentially. We implement a prototype using chameleon hashing based on discrete log and Merkle history tree. A comprehensive experimental evaluation of the proposed and existing approaches is used to validate the analytical models and verify our claims. The results demonstrate that our proposed scheme verifying in a concurrent way is significantly more efficient than the previous tree-based approach.

Chu et al. (ASIACCS 2012) proposed group signature with time-bound keys (GS-TBK) where each signing key is associated to an expiry time τ. In addition to prove the membership of the group, a signer needs to prove that the expiry time has not passed, i.e., t\textbackslashtextlessτ where t is the current time. A signer whose expiry time has passed is automatically revoked, and this revocation is called natural revocation. Simultaneously, signers can be revoked before their expiry times have passed due to the compromise of the credential. This revocation is called premature revocation. A nice property of the Chu et al. proposal is that the size of revocation lists can be reduced compared to those of Verifier-Local Revocation (VLR) group signature schemes, by assuming that natural revocation accounts for most of signer revocations in practice, and prematurely revoked signers are only a small fraction. In this paper, we point out that the definition of traceability of Chu et al. did not capture unforgeability of expiry time of signing keys which guarantees that no adversary who has a signing key associated to an expiry time τ can compute a valid signature after τ has passed. We introduce a security model that captures unforgeability, and propose a GS-TBK scheme secure in the new model. Our scheme also provides the constant signing costs whereas those of the previous schemes depend on the bit-length of the time representation. Finally, we give implementation results, and show that our scheme is feasible in practical settings.

Genomic privacy has attracted much attention from the research community, mainly since its risks are unique and breaches can lead to terrifying leakage of most personal and sensitive information. The much less explored topic of genomic security needs to mitigate threats of the digitized genome being altered by its owner or an outside party, which can have dire consequences, especially, in medical or legal settings. At the same time, many anticipated genomic applications (with varying degrees of trust) require only small amounts of genomic data. Supporting such applications requires a careful balance between security and privacy. Furthermore, genome's size raises performance concerns. We argue that genomic security must be taken seriously and explored as a research topic in its own right. To this end, we discuss the problem space, identify the stakeholders, discuss assumptions about them, and outline several simple approaches based on common cryptographic techniques, including signature variants and authenticated data structures. We also present some extensions and identify opportunities for future research. The main goal of this paper is to highlight the importance of genomic security as a research topic in its own right.