In this paper, we propose a novel zero knowledge grouping proof protocol for RFID Systems. Over the years, several protocols have been proposed in this area but they are either found to be vulnerable to certain attacks or do not comply with the EPC Class 1 Gen 2 (C1G2) standard because they use hash functions or other complex encryption schemes. Also, the unique design requirements of grouping proofs have not been fully addressed by many. Our protocol addresses these important security and design gaps in grouping proofs. We present a novel approach based on pseudo random squares and quadratic residuosity to realize a zero knowledge system. Tag operations are limited to functions such as modulo (MOD), exclusive-or (XOR) and 128 bit Pseudo Random Number Generators (PRNG). These can be easily implemented on passive tags and hence achieves compliance with the EPC Global standard while meeting the security requirements.
The role-based access control (RBAC) is a natural and versatile model of the access control principle. In the real world, it is common that an organization provides a service to a user who owns a certain role that was issued by a different organization. However, such a trans-organizational RBAC is not common in a computer network because it is difficult to establish both the security that prohibits malicious impersonation of roles and the flexibility that allows small organizations/individual users to fully control their own roles. This study proposes a system that makes use of Bitcoin technology to realize a trans-organizational RBAC mechanism. Bitcoin, the first decentralized digital currency, is a payment network that has become a platform for innovative ideas. Bitcoin’s technology, including its protocol, cryptography, and open-source nature, has built a good reputation and has been applied in other applications, such as trusted timestamping. The proposed system uses Bitcoin technology as a versatile infrastructure to represent the trust and endorsement relationship that are essential in RBAC and to realize a challenge-response authentication protocol that verifies a user's ownership of roles.
Non-interactive zero-knowledge (NIZK) proofs for algebraic relations in a group, such as the GrothSahai proofs, are an extremely powerful tool in pairing-based cryptography. A series of recent works focused on obtaining very efficient NIZK proofs for linear spaces in a weaker quasi-adaptive model. We revisit recent quasiadaptive NIZK constructions, providing clean, simple, and improved constructions via a conceptually different approach inspired by recent developments in identity-based encryption. We then extend our techniques also to linearly homomorphic structure-preserving signatures, an object both of independent interest and with many applications.
Patrick McCorry, Siamak F. Shahandashti, Dylan Clarke, Feng Hao
Abstract. Bitcoin is designed to protect user anonymity (or pseudonymity) in a financial transaction, and has been increasingly adopted by major e-commerce websites such as Dell, PayPal and Expedia. While the anonymity of Bitcoin transactions has been extensively studied, little attention has been paid to the security of post-transaction correspondence. In a commercial ap-plication, the merchant and the user often need to engage in follow-up corre-spondence after a Bitcoin transaction is completed, e.g., to acknowledge the receipt of payment, to confirm the billing address, to arrange the product de-livery, to discuss refund and so on. Currently, such follow-up correspondence is typically done in plaintext via email with no guarantee on confidentiality. Obviously, leakage of sensitive data from the correspondence (e.g., billing ad-dress) can trivially compromise the anonymity of Bitcoin users. In this paper, we initiate the first study on how to realise end-to-end secure communica-tion between Bitcoin users in a post-transaction scenario without requiring any trusted third party or additional authentication credentials. This is an important new area that has not been covered by any IEEE or ISO/IEC se-curity standard, as none of the existing PKI-based or password-based AKE schemes are suitable for the purpose. Instead, our idea is to leverage the Bit-coin’s append-only ledger as an additional layer of authentication between previously confirmed transactions. This naturally leads to a new category of AKE protocols that bootstrap trust entirely from the block chain. We call this new category “Bitcoin-based AKE ” and present two concrete protocols: one is non-interactive with no forward secrecy, while the other is interactive with additional guarantee of forward secrecy. Finally, we present proof-of-concept prototypes for both protocols with experimental results to demonstrate their practical feasibility.
Feroz Ahmad Ahmad, Prashant Kumar, Gulshan Shrivastava, Med Salim Bouhlel
ON 12 JANUARY 2009 a pseudonymous entity signed a transaction that instructed a distributed network to transfer a small amount of digital currency to Hal Finney, one ofthe key figures of the cypherpunk movement. After a few minutes, the transaction was recorded on a distributed public ledger, permanently updating the balance ofbothparties. This transaction— the first Bitcoin transaction—marked the beginning of a new era of decentralized payment systems, ushering in a variety of financial Services that do not depend on any centralized clearinghouse or other financial middleman. Bitcoin is regarded by many as a powerful technological innovation that could disrupt many sectors, in the realm of finance and beyond. But the underlying technology on which the network operates, the Bitcoin blockchain can do much more than that. Just as the internet did in the early-1990s, blockchain technology carries with it a whole new range of promises concerning how decentralization can support and promote individual freedoms and autonomy. Blockchain proponents believe that Bitcoin and other cryptocurrency platforms will revolutionize mechanisms of value exchange in the same way that the internet transformed information sharing, by providing a platform for people to exchange digital resources, in a secure and decentralized manner without the need to rely on any intermediary or trusted authority. But this revolutionary potential also carries with it serious implications for censorship, intellectual property, and the regulated flow of information. A blockchain is a decentralized database of transactions maintained by a distributed network of computers, which all contribute to the verification and the validation of transactions. Once accepted, these transactions are recorded inside a “block” of transactions, which incorporates a reference to previous blocks. This creates a long chain of blocks—a “blockchain”—that stores the history of all transactions in a chronological order. Every block contains information about a particular set of transactions, a reference to the preceding block in the blockchain, and the answer to a complex mathematical puzzle that is used to validate the data associated with that block. A copy of the blockchain is stored on every computer in the network, making it virtually impossible for anyone unilaterally to modify the data stored on this decentralized database: if anyone tries to modify any transaction the fraud will be immediately detected by all other network participants.
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Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
In this paper, we propose a secure yoking proof protocol for RFID passive tags based on Zero Knowledge. The protocols that have been proposed earlier are either found to be vulnerable to certain attacks or do not comply with EPC standard for passive tags because they use complex encryption schemes. Also, the unique design requirements of yoking/grouping proofs have not been fully addressed by many. Our protocol addresses these important security and design gaps in yoking proofs. The proposed protocol uses pseudo random squares and quadratic residuosity to realize the zero knowledge property. Tag operations are limited to functions such as modulo (MOD), exclusive-or (XOR) and 128-bit Pseudo Random Number Generators (PRNG). Passive tags are capable of these operations and hence the protocol achieves EPC compliance and also meets the necessary security requirements.
In this paper, we describe our analysis of a recently proposed electric vehicle charing protocol. The protocol builds on complicated cryptographic primitives such as commitment, zero-knowledge proofs, BBS+ signature and etc. Moreover, interesting properties such as secrecy, authentication, anonymity, and location privacy are claimed on this protocol. It thus presents a challenge for formal verification, as existing tools for security protocol analysis lack support for all the required features. In our analysis, we employ and combine the strength of two state-of-the-art symbolic verifiers, Tamarin and Prove if, to check all important properties of the protocol.
Michel Abdalla⋆, Fabrice Benhamouda, David Pointcheval
Indistinguishability under adaptive chosen-ciphertext attack (IND-CCA) is now consid- ered the de facto security notion for public-key encryption. However, the security guarantee that it oers is sometimes stronger than what is needed by certain applications. In this paper, we consider a weaker notion of security for public-key encryption, termed indistinguishability under plaintext- checking attacks (IND-PCA), in which the adversary is only given access to an oracle which says whether or not a given ciphertext encrypts a given message. After formalizing the IND-PCA notion, we then design a new public-key encryption scheme satisfying it. The new scheme is a more e- cient variant of the Cramer-Shoup encryption scheme with shorter ciphertexts and its security is also based on the plain Decisional Die-Hellman ( DDH) assumption. Additionally, the algebraic properties of the new scheme also allow for proving plaintext knowledge using Groth-Sahai non- interactive zero-knowledge proofs or smooth projective hash functions. Finally, in order to illustrate the usefulness of the new scheme, we further show that, for many password-based authenticated key exchange (PAKE) schemes in the Bellare-Pointcheval-Rogaway security model, one can safely replace the underlying IND-CCA encryption schemes with our new IND-PCA one. By doing so, we were able to reduce the overall communication complexity of these protocols and obtain the most ecient PAKE schemes to date based on the plain DDH assumption.
Joseph A. Akinyele, Gilles Barthe, Benjamin Grégoire, Benedikt Schmidt · 5 authors
Many algorithms admit very efficient batch versions that compute simultaneously the output of the algorithms on a set of inputs. Batch algorithms are widely used in cryptography, especially in the setting of pairing-based computations, where they deliver significant speed-ups. Auto Batch is an automated tool that computes highly optimized batch verification algorithms for pairing-based signature schemes. Thanks to finely tuned heuristics, Auto Batch is able to rediscover efficient batch verifiers for several signature schemes of interest, and in some cases to output batch verifiers that outperform the best known verifiers from the literature. However, Auto Batch only provides weak guarantees (in the form of a LaTeX proof) of the correctness of the batch algorithms it outputs. In this paper, we verify the correctness and security of these algorithms using the Easy Crypt framework. To achieve this goal, we define a domain-specific language to describe verification algorithms based on pairings and provide an efficient algorithm for checking (approximate) observational equivalence between expressions of this language. By translating the output of Auto Batch to this language and applying our verification procedure, we obtain machine-checked correctness proofs of the batch verifiers. Moreover, we formalize notions of security for batch verifiers and we provide a generic proof in Easy Crypt that batch verifiers satisfy a security property called screening, provided they are correct and the original signature is unforgeable against chosen-message attacks. We apply our techniques to several well-known pairing-based signature schemes from the literature, and to Groth-Sahai zero-knowledge proofs.
With an estimated 50 billion internet-enabled devices deployed by 2020, the arrival of the Internet of Things (IoT) or Internet of Everything (IoE) raises many questions regarding the suitability and adaptability of current computer security standards to provide privacy, data integrity and end entity authentication between communicating peers. In this paper we present a new protocol which combines zero-knowledge proofs and key exchange mechanisms to provide secure and authenticated communication in static machine-to-machine (M2M) networks. This approach addresses all of the aforementioned issues while also being suitable for devices with limited computational resources and can be deployed in wireless sensor networks. While the protocol requires an a-priori knowledge about the network setup and structure, it guarantees perfect forward secrecy.
We present a new type system for verifying the security of reference implementations of cryptographic protocols written in a core functional programming language. The type system combines prior work on refinement types, with union, intersection, and polymorphic types, and with the novel ability to reason statically about the disjointness of types. The increased expressivity enables the analysis of important protocol classes that were previously out of scope for the type-based analyses of reference protocol implementations. In particular, our types can statically characterize: (i) more usages of asymmetric cryptography, such as signatures of private data and encryptions of authenticated data; (ii) authenticity and integrity properties achieved by showing knowledge of secret data; (iii) applications based on zero-knowledge proofs. The type system comes with a mechanized proof of correctness and an efficient type-checker.
Zero-knowledge proofs were introduced by Goldwasser, Micali, and Rackoff. A zero-knowledge proof allows a prover to demonstrate knowledge of some information, for example that they know an element which is a member of a list or which is not a member of a list, without disclosing any further information about that element. Existing constructions of zero-knowledge proofs which can be applied to all languages in NP are impractical due to their communication and computational complexity. However, it has been known since Guillou and Quisquater's identification protocol from 1988 and Schnorr's identification protocol from 1991 that practical zero-knowledge protocols for specific problems exist. Because of this, a lot of work was undertaken over the recent decades to find practical zero-knowledge proofs for various other specific problems, and in recent years many protocols were published which have improved communication and computational complexity. Nevertheless, to find more problems which have an efficient and practical zero-knowledge proof system and which can be used as building blocks for other protocols is an ongoing challenge of modern cryptography. This work addresses the challenge, and constructs zero-knowledge arguments with sublinear communication complexity, and achievable computational demands. The security of our protocols is only based on the discrete logarithm assumption. Polynomial evaluation arguments are proposed for univariate polynomials, for multivariate polynomials, and for a batch of univariate polynomials. Furthermore, the polynomial evaluation argument is applied to construct practical membership and non-membership arguments. Finally, an efficient method for proving the correctness of a shuffle is proposed. The proposed protocols have been tested against current state of the art versions in order to verify their practicality in terms of run-time and communication cost. We observe that the performance of our protocols is fast enough to be practical for medium range parameters. Furthermore, all our verifiers have a better asymptotic behavior than earlier verifiers independent of the parameter range, and in real life settings our provers perform better than provers of existing protocols. The analysis of the results shows that the communication cost of our protocols is very small; therefore, our new protocols compare very favorably to the current state of the art.
The practical deployment of vehicular networks is still a pending issue. In this paper we describe a new self-organized method of authentication for VANETs, which allows their widespread, fast and secure implementation. Our proposal does not involve any central certification authority because the nodes themselves certify the validity of public keys of the other nodes. On the one hand we propose an algorithm that each node must use to choose the public key certificates for its local store. On the other hand, we also describe a new node authentication method based on a cryptographic protocol including a zero-knowledge proof that each node must use to convince another node on the possession of certain secret without revealing anything about it, which allows non-encrypted communication during authentication. Thanks to the combination of the aforementioned tools, the cooperation among vehicles can be used for developing several practical applications of VANETs, such as detection and warning about abnormal traffic conditions. One of the most interesting aspects of our proposal is that it only requires existing devices such as smartphones, because the designed schemes are fully distributed and self-organized. In this work we include an analysis of both an NS-2 simulation and a real device implementation of the proposed algorithms, which enables us to extract promising conclusions and several possible improvements and open questions for further research.
One of the central problems in the development of distributed systems is the design of cryptographic protocols that meet specified functional requirements and preserve user privacy. Methods of conventional encryption algorithms typically use PKI. In this paper we presented a method based on other approach. The authors have developed a cryptographic framework for access control, ensured the confidentiality of social relations, secrecy of resources and anonymity of users in social networks. The implementation of the protocols in the framework is combination of zero-knowledge proof and signature schemes Camenisch-Lysyanskaya.
Almost all existing password-based authenticated key exchange (PAKE) schemes achieve concurrent security in the standard model by relying on the common reference string (CRS) model. A drawback of the CRS model is to require a centralized trusted authority in the setup phase; thus, passwords of parties may be revealed if the authority ill-uses trapdoor information of the CRS. There are a few secure PAKE schemes in the plain model, but, these are not achievable in a constant round (i.e., containing a linear number of rounds). In this paper, we discuss how to relax the setup assumption for (constant round) PAKE schemes. We focus on the multi-string (MS) model that allows a number of authorities (including malicious one) to provide some reference strings independently. The MS model is a more relaxed setup assumption than the CRS model because we do not trust any single authority (i.e., just assuming that a majority of authorities honestly generate their reference strings). Though the MS model is slightly restrictive than the plain model, it is very reasonable assumption because it is very easy to implement. We construct a (concurrently secure) three-move PAKE scheme in the MS model (justly without random oracles) based on the Groce-Katz PAKE scheme. The main ingredient of our scheme is the multi-string simulation-extractable non-interactive zero-knowledge proof that provides both the simulation-extractability and the extraction zero-knowledge property even if minority authorities are malicious. This work can be seen as a milestone toward constant round PAKE schemes in the plain model.