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535 results · page 14 of 23
Wei She, Lijuan Huo, Tian Zhao, Yan Zhuang · 6 authors
No abstract is available for this record.
Meenakshi Kansal, Ratna Dutta, Sourav Mukhopadhyay
Abstract A nominative signature (NS) is a cryptographic primitive where two parties collude to produce a signature. It is a user certification system and has applications in a variety of sectors where nominee cannot trust heavily on the nominator to validate the nominee's certificate and only targeted entities are allowed to verify the signature on sensitive data. A new construction for NS from standard assumptions on lattice is provided. The authors’ construction relies on collision‐resistant preimage sampleable function and symmetric key primitives like collision‐resistant pseudorandom function and zero knowledge proof system ZKB ++ for Boolean circuits. The authors provide detailed security analysis and show that their construction achieves security under unforgeability , invisibility , impersonation , and non‐repudiation in the existing model. Furthermore, our construction exhibits non‐transferability . The security under non‐repudiation is achieved in the quantum random oracle model using Unruh transform to ZKB ++ .
Alem Fitwi, Yu Chen
At present, more than a billion closed-circuit television (CCTV) cameras are watching the world. These cameras garner a lot of visual information that is often processed and stored in remote and centralized cloud servers. Multiple occasions have revealed that this traditional approach is plagued with security and privacy breaches. The breaches could be the interception of raw videos while in transit to distant surveillance analytics centers (SAC), infiltration to cameras and network video records (NVR), or abuse of cameras and stored videos. Hence, the traditional video surveillance system (VSS) cannot guarantee the protection of the privacy of individuals caught on CCTV cameras. Therefore, this paper proposes a Secure and Privacy-preserving Stored surveillance video sharing (SePriS) mechanism for authorized users/nodes based on blockchain (BC), smart contracts, and the enciphering of video frames using DAB, a mechanism developed based on discrete cosine transform (DCT), advanced encryption standard (AES), and a block shuffling (BS) algorithm. The BC-based solution creates an environment auspicious for creating decentralized, reliable SACs and storage sites with secure and privacy-aware sharing of stored surveillance videos across SAC nodes and by law enforcers, police departments, and courts securely connected to the SAC nodes. The experiments and analyses validate that the proposed BC-based SePriS solution achieves the design purpose.
Yaron Gvili
LibSWIFFT is an open-source, production-ready C/C++ library providing SWIFFT, one of the fastest available secure hash functions that is also collision-resistant. SWIFFT also facilitates post-quantum digital signature schemes and zero-knowledge proofs of knowledge of a preimage (ZKPoKP). LibSWIFFT is optimized for short blocks of input and runs at a rate of less than 5 cycles/byte single-threaded on a modern commodity computer with AVX2. Other software providing SWIFFT, which are not claiming production-readiness as LibSWIFFT is, are the original implementation by the authors of SWIFFT (Micciancio, 2016) and the SWIFFT 8-bit (Karati & Safavi-Naini, 2018b) and 16-bit (Karati & Safavi-Naini, 2018a) AVX2 implementations for the multi-signature scheme K2SN-MSS (Karati & Safavi-Naini, 2019).
S. Banupriya, Kottilingam Kottursamy, Ali Kashif Bashir
No abstract is available for this record.
Peijun Zhang, Lianhai Wang, Wei Wang, Kunlun Fu · 5 authors
Blockchain, which has a distributed structure, has been widely used in many areas. Especially in the area of smart cities, blockchain technology shows great potential. The security issues of blockchain affect the construction of smart cities to varying degrees. With the rapid development of quantum computation, elliptic curves cryptosystems used in blockchain are not secure enough. This paper presents a blockchain system based on lattice cipher, which can resist the attack of quantum computation. The most challenge is that the size of public keys and signatures used by lattice cryptosystems is typically very large. As a result, each block in a blockchain can only accommodate a small number of transactions. It will affect the running speed and performance of the blockchain. For overcoming this problem, we proposed a way that we only put the hash values of public keys and signatures on the blockchain and store the complete content of them on an IPFS (interplanetary file system). In this way, the number of bytes occupied by each transaction is greatly reduced. We design a bitcoin exchange scheme to evaluate the performance of the proposed quantum-resistant blockchain system. The simulation platform is verified to be available and effective.
Zerui Chen, Youliang Tian, Changgen Peng
No abstract is available for this record.
Dilbag Singh
It is undeniable that the growth of the computer and network security is repeatedly increased since the past 40 years. In 1985-1986 encryption was applied as a primary technique for providing security. Network security technology includes authentication and authorisation, data encryption, access control and security auditing. Bitcoin is presently one of the most popular crypto-currencies. The phenomenon of Bitcoin crypto-currencies is based on the public key cryptography and peer to peer network. In the Bitcoin, blockchain is used for storage of the transaction which is also called the public ledger. Digital money or Bitcoin is used in day to day activities, some of which are illicit and illegal. In this paper, the main area is security, i.e., the main focus here is to protect Bitcoin systems from unauthorised access and from various threats using an appropriate scheme (elliptic-curve cryptography, ECC) protocol.
John J A Burke
No abstract is available for this record.
F. Richard Yu, Jeremy J. James, Zhu Li, Zhaowei Ma
Surveillance is being pervasively used, and its recording is extensively applied in practice. Thereby, protection of surveillance recordings, which is related to multimedia security, increasingly attracts research interests. Traditional techniques, such as watermarking, cryptography and steganography, focus on analysing multimedia content, resulting in high complexity and long latency, which makes them not suitable for protecting real-time surveillance applications. In this paper, we propose a novel blockchain-assisted framework to protect the recordings in real-time surveillance applications. In the proposed framework, we design an algorithm that generates frame fingerprints, which involves real-time extraction of packets from surveillance multimedia streams, SHA3-512 functions, and the verification of frame consistency. We use a blockchain for preserving the frame fingerprints generated by our proposed algorithm. Different from existing works that use simulations to show the performance, we develop a real system using a service-oriented blockchain, virtualisation for distributed ledger technology (vDLT), and the effectiveness of this system is demonstrated.
Aleksandr Ometov, Krystof Zeman, Pavel Mašek, Lukas Balazevic · 5 authors
With technology evolving rapidly and proliferating, it is imperative to pay attention to mobile devices’ security being currently responsible for various sensitive data processing. This phase is essential as an intermediate before the cloud or distributed ledger storage delivery and should be considered additional care due to its inevitability. This paper analyzes the security mechanisms applied for internal use in the Android OS and the communication between the Android OS and the remote server. Presented work aims to examine these mechanisms and evaluate which cryptographic methods and procedures are most advantageous in terms of energy efficiency derived from execution time. Nonetheless, the dataset with the measurements collected from 17 mobile devices and the code for reproducibility is also provided. After analyzing the collected data, specific cryptographic algorithms are recommended to implement an application that utilizes native cryptographic operations on modern Android devices. In particular, selected algorithms for symmetric encryption are AES256 / GCM / No Padding; for digital signature – SHA512 with RSA2048 / PSS, and for asymmetric encryption – RSA3072 / OAEP with SHA512 and MGF1 Padding.
Vijay Kumar Yadav, Rakesh Kumar Yadav, Brijesh Kumar Chaurasia, Shekhar Verma · 5 authors
No abstract is available for this record.
David Chaum, Mario Larangeira, Mario Yaksetig, William Carter
No abstract is available for this record.
Emilio Barucci, Giancarlo Giuffra Moncayo, Daniele Marazzina
Abstract We analyze cryptoasset markets (cryptocurrencies and stablecoins) at high frequency. We investigate intraday patterns. We show that Tether plays a crucial role as a safe haven and/or store of value facilitating trading in cryptocurrencies without going through traditional currencies. Markets centered on cryptocurrencies and stablecoins play a primary role aggregating preference/technology shocks and heterogeneous opinions, instead markets centered on the US dollar play a marginal role on price formation.
Maanas Midha, Amit Kumar Gupta, Priya Mathur
No abstract is available for this record.
Shuichi Katsumata
Many of the recent advanced lattice-based \(\varSigma \)-/public-coin honest verifier (HVZK) interactive protocols based on the techniques developed by Lyubashevsky (Asiacrypt’09, Eurocrypt’12) can be transformed into a non-interactive zero-knowledge (NIZK) proof in the random oracle model (ROM) using the Fiat-Shamir transform. Unfortunately, although they are known to be secure in the classical ROM, existing proof techniques are incapable of proving them secure in the quantum ROM (QROM). Alternatively, while we could instead rely on the Unruh transform (Eurocrypt’15), the resulting QROM secure NIZK will incur a large overhead compared to the underlying interactive protocol.
Mar Gimenez-Aguilar, José M. de Fuentes, Lorena González‐Manzano, Carmen Cámara
Permanent availability makes blockchain technologies a suitable alternative for building a covert channel. Previous works have analysed its feasibility in a particular blockchain technology called Bitcoin. However, Ethereum cryptocurrency is gaining momentum as a means to build distributed apps. The novelty of this paper relies on the use of Ethereum to establish a covert channel considering all transaction fields and smart contracts. No previous work has explored this issue. Thus, a mechanism called$Zephyrus$, an information hiding mechanism based on steganography, is developed. Moreover, its capacity, cost and stealthiness are assessed both theoretically, and empirically through a prototype implementation that is publicly released. Disregarding the time taken to send the transaction to the blockchain, its retrieval and the mining time, experimental results show that, in the best case, 40 Kbits can be embedded in 0.57 s. for US$\$ $1.64, and retrieved in 2.8 s.
Alexandru Cojocaru, Juan A. Garay, Aggelos Kiayias, Fang Song · 5 authors
A proof of work (PoW) is an important cryptographic construct enabling a party to convince others that they invested some effort in solving a computational task. Arguably, its main impact has been in the setting of cryptocurrencies such as Bitcoin and its underlying blockchain protocol, which received significant attention in recent years due to its potential for various applications as well as for solving fundamental distributed computing questions in novel threat models. PoWs enable the linking of blocks in the blockchain data structure and thus the problem of interest is the feasibility of obtaining a sequence (chain) of such proofs. In this work, we examine the hardness of finding such chain of PoWs against quantum strategies. We prove that the chain of PoWs problem reduces to a problem we call multi-solution Bernoulli search, for which we establish its quantum query complexity. Effectively, this is an extension of a threshold direct product theorem to an average-case unstructured search problem. Our proof, adding to active recent efforts, simplifies and generalizes the recording technique of Zhandry (Crypto'19). As an application, we revisit the formal treatment of security of the core of the Bitcoin consensus protocol, the Bitcoin backbone (Eurocrypt'15), against quantum adversaries, while honest parties are classical and show that protocol's security holds under a quantum analogue of the classical “honest majority'' assumption. Our analysis indicates that the security of Bitcoin backbone is guaranteed provided the number of adversarial quantum queries is bounded so that each quantum query is worth <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>O</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:msup><mml:mi>p</mml:mi><mml:mrow class="MJX-TeXAtom-ORD"><mml:mo>&#x2212;</mml:mo><mml:mn>1</mml:mn><mml:mrow class="MJX-TeXAtom-ORD"><mml:mo>/</mml:mo></mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msup><mml:mo stretchy="false">)</mml:mo></mml:math> classical ones, where <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>p</mml:mi></mml:math> is the success probability of a single classical query to the protocol's underlying hash function. Somewhat surprisingly, the wait time for safe settlement in the case of quantum adversaries matches the safe settlement time in the classical case.
Cheman Shaik
A cryptographic method of digitally securing cryptocurrency wallet seed phrase through Blind Key Encryption is discussed wherein two blind keys random in nature are generated and used to produce two ciphertexts. The mathematical algorithm used in blind key encryption is described in detail and also an explanation is provided as to how the encryption defeats hackers even after they could successfully compromise a ciphertext of the seed phrase along with its decryption key. Different scenarios of storing the ciphertexts are documented.
Novak Kaluđerović, Thorsten Kleinjung, Dušan Kostić
Linear Legendre pseudorandom functions were introduced in 1988 by Damgrd, and higher degree generalisations were introduced by Russell and Shparlinski in 2004. We present new key recovery methods that improve the state of the art for both cases. For degree r 3 we give an attack that runs in time O( p r -3 ) after O( p 3 ) precomputation for the most relevant high degree case; it is based on the action of the group of Mbius transformations on degree r polynomials. For r < 3 we give an O( p r/2 ) attack with O( p r/4 ) oracle queries. In the linear case we recovered the keys for the 64, 74 and 84-bit prime Ethereum challenges, being the first to solve the 84-bit case.
Mikhail Krasnoselskii, Grigorii Melnikov, Yury Yanovich
Random number generators (RNG) are both building blocks and services on the top of distributed ledgers like blockchains and directed acyclic graphs. In the paper, the authors provide implementation and demonstration of the fault-tolerant RNG algorithm–No-Dealer–for a public directed acyclic graph-based platform called Hedera Hashgraph. The performance tests on the Hedera testnet show that the system meets the real-world requirements. The proposed solution can be used as an RNG service.
Sven-Jannik Wöhnert, Kai Hendrik Wöhnert, Eldar Almamedov, Volker Skwarek
Proof of integrity in produced video data by surveillance cameras requires active forensic methods such as signatures, otherwise authenticity and integrity can be comprised and data becomes unusable e. g. for legal evidence. But a simple file- or stream-signature loses its validity when the stream is cut in parts or by separating data and signature. Using the principles of security in distributed systems similar to those of blockchain and distributed ledger technologies (BC/DLT), a chain which consists of the frames of a video which frame hash values will be distributed among a camera sensor network is presented. The backbone of this Framechain within the camera sensor network will be a camera identity concept to ensure accountability, integrity and authenticity according to the extended CIA triad security concept. Modularity by secure sequences, autarky in proof and robustness against natural modulation of data are the key parameters of this new approach. It allows the standalone data and even parts of it to be used as hard evidence.
Ryan Henry, Alyssa Tory, Sophie Henry, Isabella Henry · 5 authors
In this short paper, we revisit the celebrated Naor?Naor?Reingold (NNR) protocol for ?[convincing] people you know where Waldo is without revealing information about his location?. We observe that, despite oft-repeated claims to the contrary, the NNR protocol is neither zero-knowledge nor a proof of knowledge. We propose a slightly more elaborate version that is both of these things?but still eminently suitable for children?s playdates (and the classroom).
Auqib Hamid Lone, Roohie Naaz
One of the backbone technology of Blockchains is cryptography. In simpler terms cryptography is the mathematical art of secret writing, however it's applications are not limited to writing secret codes only. Essentially cryptography is used to achieve three main security goals namely confidentiality (in-formation must be hidden from the unintended users), integrity (information must be prevented from illicit modifications) and availability (information must be readily available to intended users at all times). In cryptography confidentiality is achieved by employing a technique called as Encryption, integrity is achieved by employing special one way functions called as Cryptographic Hash Functions and authentication (process for verifying identity of the sender) is achieved by employing a technique called as Digital Signatures. For better understanding about the working of Blockchain it is essential to understand cryptographic concepts on which Blockchain is built. This paper presents the brief overview of such cryptographic concepts. In particular this papers throws light on the cryptographic concepts used to build Bitcoin and Ethereum Blockchains. Furthermore this paper also throws light on the need and requirements of post-quantum cryptographic primitives for post-quantum Blockchains.