An arbitrated quantum signature scheme based on entanglement swapping and hash functions

We propose an arbitrated quantum signature (AQS) scheme with continuous variable (CV) squeezed vacuum states, which requires three parties, i.e., the signer Alice, the verifier Bob and the arbitrator Charlie trusted by Alice and Bob, and three phases consisting of the initial phase, the signature phase and the verification phase. We evaluate and compare the original state and the teleported state by using the fidelity and the beam splitter (BS) strategy. The security is ensured by the CV-based quantum key distribution (CV-QKD) and quantum teleportation of squeezed states. Security analyses show that the generated signature can be neither disavowed by the signer and the receiver nor counterfeited by anyone with the shared keys. Furthermore, the scheme can also detect other manners of potential attack although they may be successful. Also, the integrality and authenticity of the transmitted messages can be guaranteed. Compared to the signature scheme of CV-based coherent states, our scheme has better encoding efficiency and performance. It is a potential high-speed quantum signature scheme with high repetition rate and detection efficiency which can be achieved by using the standard off-the-shelf components when compared to the discrete-variable (DV) quantum signature scheme.

Hash functions, which can extract message digest from input messages as output, play an important role in digital signature and authentication. Meanwhile, Hash functions are essential in many cryptographic protocols and regimes. With the research becoming more and more in depth, a series of Hash functions is proposed, such as MD series and SHA series. At the same time, the security analysis and attacks against Hash functions are carried out. The security of Hash functions is threatened. In this case, how to improve the security of the Hash functions becomes the primary concern. In this paper, an optical Hash function based on the interaction between light and multiple scattering media is proposed. Unlike most of the traditional Hash functions which are based on mathematical transformations or complex logic operations, this method innovatively takes advantage of the natural random scattering effect of multiple scattering media on coherently modulated light, and realizes the “confusion” and “diffusion” of modulated light, which satisfies the core functional requirement of the Hash function: one-way encoding/encryption with strong security. The photoelectric hybrid system designed by this method can effectively simulate the "compression function" in the Hash function. Combined with the Sobel filter with feature extraction function, the input data of arbitrary length can be compressed and encrypted into the output with a fixed length of 256-bit (Hash value). The principle of the proposed optical Hash function can be described as follows. 1) Two 8-bit images with a size of 16×16 pixels are loaded in SLM<sub>1</sub> (amplitude-only spatial modulator) and SLM<sub>2</sub> (phase-only spatial modulator) respectively. 2) The coherent wavefront is modulated by SLM<sub>1</sub> and SLM<sub>2</sub>, and then propagates on multiple scattering media. 3) A speckle pattern is recorded by CCD because of the confusion of multiple scattering media. 4) The features of the speckle pattern, which is extracted by Sobel filter, serve as the input of the next compression function. For the unpredicted and non-duplicated disorder multiple scattering media, it is tremendously difficult to determine the internal state of the multiple scattering media. Therefore, the proposed optical Hash function is considered to have a high security. A series of simulation results shows that the proposed optical Hash function has a good “avalanche effect” and “collision resistance”, and its security performance is comparable to that of the most widely used traditional Hash functions (MD5 and SHA-1).

Arbitrated signature provides that the signatory signs a message with his private key by quantum cryptography, while the signature receiver verifies the signature with the arbitrator’s assistance. In this work, security analysis was given to the arbitrated quantum signature (AQS) and results showed that the receiver Bob and the attacker can forge the signature. Then this paper gives a new quantum one-time pads encryption method, which is suit for the quantum signature. At last, a new AQS protocol using Einstein-Podoisky-Rosen (EPR) pairs is proposed. By using of quantum key distribution (QKD) and new quantum one-time pads, the new scheme can resist Shor’s attack. The new scheme has following advantages: (1) The scheme reduces the complexity of implementation and provides a higher efficiency in transmission; (2) Compares with some AQS schemes, the scheme can avoid being disavowed by the receiver; (3) Compares with other AQS schemes, the scheme also guarantees the arbitrator cannot forge the signature and it also ensure the receiver and other attacker cannot forge the signature.

Recently, a fast and secure hash function SFHA - 256 has been proposed and claimed as more secure and as having a better performance than the SHA - 256. In this paper an improved version of SFHA - 256 is proposed and analyzed using two parameters, namely the avalanche effect and uniform deviation. The experimental results and further analysis ensures the performance of the newly proposed and improved SFHA-256. From the analysis it can be concluded that the newly proposed algorithm is more secure, efficient, and practical.

When we want to sign a quantum message that we create, we can use arbitrated quantum signature schemes which are possible to sign for not only known quantum messages but also unknown quantum messages. However, since the arbitrated quantum signature schemes need the help of a trusted arbitrator in each verification of the signature, it is known that the schemes are not convenient in practical use. If we consider only known quantum messages such as the above situation, there can exist a quantum signature scheme with more efficient structure. In this paper, we present a new quantum signature scheme for known quantum messages without the help of an arbitrator. Differing from arbitrated quantum signature schemes based on the quantum one-time pad with the symmetric key, since our scheme is based on quantum public-key cryptosystems, the validity of the signature can be verified by a receiver without the help of an arbitrator. Moreover, we show that our scheme provides the functions of quantum message integrity, user authentication and non-repudiation of the origin as in digital signature schemes.

Hash functions are important security primitives used for authentication and data integrity. Among the most popular hash functions are MD5, SHA-1, and RIPEMD-160, which are all based on the function MD4. This similarity can be exploited for designing a unified engine to perform all three hash functions. Hash message authentication code (HMAC) is a shared-key security algorithm that uses these hash functions alternatively for IPSec authentication. Since some other security applications, such as digital signature, also use these three hash functions, it is prudent to design a unified, reconfigurable engine that can perform any one of them alone or with HMAC. In this work, we design an HMAC-hash unit that can be reconfigured to perform one of six standard security algorithms; namely, MD5, SHA-1, RIPEMD-160, HMAC-MD5, HMAC-SHA-1, and HMAC-RIPEMD-160. This paper applied pipelining and parallelism to the design of the HMAC-hash unit to improve throughput, especially for large message sizes. We achieved higher throughput than engines that integrated three hash functions or more and comparable throughput to those integrated only two hash functions.

The hash function used is known for implementing algorithmic solutions in programming. Hash functions encrypt and optimize work with processed and stored data, as well as in various operating systems, ranking data to ensure their integrity. The application of the hash function is quite extensive. The usage of the hash function allows the possibility to solve almost all problems of protecting electronic information, from ensuring the authenticity of subjects and objects of information interaction to introducing uncertainty into the operation of means and objects of protection. The article deals with hash functions used in electronic digital signature (EDS) algorithms. Modern hashing methods and the areas in which they are applicable are described. The hash function is used to secure data. These functions can vary in bit depth, complexity, and cryptographic strength. Cryptographic hashing algorithms are given parameters, structures, and methods, as well as their scope. The work is devoted to analyzing hash functions and their application in the electronic digital signature. The article presents the results of calculating collisions of hashing algorithms, allowing you to choose the most optimal option for its application in the algorithm under consideration. The practical application of the hashing algorithm for the digital signature system, which can be used in systems and networks to transmit and store information, is considered

This paper reports a thorough standard-model investigation on how attacks on hash functions impact the security of hash-and-sign signature schemes. We identify two important properties that appear to be crucial in analyzing the nature of security relations between signature schemes and their inner hash functions: primitiveness and injectivity. We then investigate the security relations in the general case of hash-and-sign signatures and in the particular case of first-hash-then-sign signatures, showing a gap of security guarantees between the two paradigms. We subsequently apply our results on two operating modes to construct a hash function family from a hash function based on the well-known Merkle-Damgård construction (such as MD5 and SHA-1). For completeness, we give concrete attack workloads for attacking operating modes used in practical implementations of signature schemes.KeywordsHash FunctionSignature SchemeRandom OracleCompression FunctionSecurity ProofThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

An arbitrated quantum signature scheme, which is mainly applied in electronic-payment systems, is proposed and investigated. The χ-type entangled states are used for quantum key distribution and quantum signature in this protocol. Compared with previous quantum signature schemes which also utilize χ-type entangled states, the proposed scheme provides higher efficiency. Finally, we also analyze its security under various kinds of attacks.

With the drastic growth in the addition of smart objects into the Internet, it has led to many challenges like standardizing the infrastructure, ensuring communication security and keeping user credential private. As these devices are having less resources it is necessity to have a lighter encryption and authentication schemes to ensure data integrity and user privacy. This work concentrates on evaluating the faster hashing function used for elliptic curve digital signature algorithm (ECDSA) that enables user authentication. Traditionally, SHA hash functions are used in various public key cryptography and applications. But SHA has 80 different iterations that consumes smart device's energy. Thus a lighter hash function called BLAKE2 based hashing is used to compare the time efficiency of ECDSA. BLAKE2 uses 8 rounds of permutations and combinations to produce the message digest of 256/512bits. This reduction in computation has attracted researchers to use BLAKE2 hashing functions for various applications. Thence this study concentrates on comparison of the time efficiency under ECDSA based digital signature for different message sizes and hashing functions. Through various experiments conducted on different operating systems, BLAKE2 has shown better computational efficiency than SHA family of hashing functions for ECDSA based scheme on different operating system.

Recently, formal complexity-theoretic treatment of cryptographic hash functions was suggested. Two primitives of Collision-free hash functions and Universal one-way hash function families have been defined. The primitives have numerous applications in secure information compression, since their security implies that finding collisions is computationally hard. Most notably, Naor and Yung have shown that the most secure signature scheme can be reduced to the existence of universal one-way hash (this, in turn, gives the first trapdoor-less provably secure signature scheme).In this work, we first present reductions from various one-way function families to universal one-way hash functions. Our reductions are general and quite efficient and show how to base universal one-way hash functions on any of the known concrete candidates for one-way functions. We then show equivalences among various definitions of hardness for collision-free hash functions.

: Cryptographic hash functions are fundamental primitives in modern cryptography and have many security applications (data integrity checking, cryptographic protocols, digital signatures, pseudo random number generators etc.). At the same time novel hash functions are designed (for instance in the framework of the SHA-3 contest organized by the National Institute of Standards and Technology (NIST)), the cryptanalysts exhibit a set of statistical metrics (propagation criterion, frequency analysis etc.) able to assert the quality of new proposals. Also, rules to design good hash functions are now known and are followed in every reasonable proposal of a new hash scheme. This article investigates the ways to build on this experiment and those metrics to generate automatically compression functions by means of Evolutionary Algorithms (EAs). Such functions are at the heart of the construction of iterative hash schemes and it is therefore crucial for them to hold good properties. Actually, the idea to use nature-inspired heuristics for the design of such cryptographic primitives is not new: this approach has been successfully applied in several previous works, typically using the Genetic Programming (GP) heuristic [1]. Here, we exploit a hybrid meta-heuristic for the evolutionary process called Gene Expression Programming (GEP) [2] that appeared far more efficient computationally speaking compared to the GP paradigm used in the previous papers. In this context, the GEPHashSearch framework is presented. As it is still a work in progress, this article focuses on the design aspects of this framework (individuals definitions, fitness objectives etc.) rather than on complete implementation details and validation results. Note that we propose to tackle the generation of compression functions as a multi-objective optimization problem in order to identify the Pareto front i.e. the set of non-dominated functions over the four fitness criteria considered. If this goal is not yet reached, the first experimental results in a mono-objective context are promising and open the perspective of fruitful contributions to the cryptographic community.

: Cryptographic hash functions are fundamental primitives in modern cryptography and have many security applications (data integrity checking, cryptographic protocols, digital signatures, pseudo random number generators etc.). At the same time novel hash functions are designed (for instance in the framework of the SHA-3 contest organized by the National Institute of Standards and Technology (NIST)), the cryptanalysts exhibit a set of statistical metrics (propagation criterion, frequency analysis etc.) able to assert the quality of new proposals. Also, rules to design good hash functions are now known and are followed in every reasonable proposal of a new hash scheme. This article investigates the ways to build on this experiment and those metrics to generate automatically compression functions by means of Evolutionary Algorithms (EAs). Such functions are at the heart of the construction of iterative hash schemes and it is therefore crucial for them to hold good properties. Actually, the idea to use nature-inspired heuristics for the design of such cryptographic primitives is not new: this approach has been successfully applied in several previous works, typically using the Genetic Programming (GP) heuristic [1]. Here, we exploit a hybrid meta-heuristic for the evolutionary process called Gene Expression Programming (GEP) [2] that appeared far more efficient computationally speaking compared to the GP paradigm used in the previous papers. In this context, the GEPHashSearch framework is presented. As it is still a work in progress, this article focuses on the design aspects of this framework (individuals definitions, fitness objectives etc.) rather than on complete implementation details and validation results. Note that we propose to tackle the generation of compression functions as a multi-objective optimization problem in order to identify the Pareto front i.e. the set of non-dominated functions over the four fitness criteria considered. If this goal is not yet reached, the first experimental results in a mono-objective context are promising and open the perspective of fruitful contributions to the cryptographic community.

We present a new tighter security proof for unbounded hash tree keyless signature (time-stamping) schemes that use Merkle-Damgård (MD) hash functions with Preimage Aware (PrA) compression functions. It is known that the PrA assumption alone is insufficient for proving the security of unbounded hash tree schemes against back-dating attacks. We show that many known PrA constructions satisfy a stronger Bounded Pre-Image Awareness (BPrA) condition that assumes the existence of an extractor \(\mathcal{E}\) that is bounded in the sense that for any efficiently computable query string α, the number of outputs y for which \(\mathcal{E}(y,\alpha)\) succeeds does not exceed the number of queries in α. We show that blockcipher based MD-hash functions with rate-1 compression functions (such as Davies-Meyer and Miyaguchi-Preneel) of both type I and type II are BPrA. We also show that the compression function of Shrimpton-Stam that uses non-compressing components is BPrA. The security proof for unbounded hash-tree schemes is very tight under the BPrA assumption. In order to have 2s-security against back-dating, the hash function must have n = 2s + 4 output bits, assuming that the security of the hash function is close to the birthday barrier, i.e. that there are no structural weaknesses in the hash function itself. Note that the previous proofs that assume PrA gave the estimation n = 2s + 2 log2 C + 2, where C is the maximum allowed size of the hash tree. For example, if s = 100 (2100-security) and C = 260, the previous proofs require n = 322 output bits, while the new proof requires n = 204 output bits.KeywordsHash FunctionSuccess ProbabilityBlock CipherRandom OracleCompression FunctionThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Due to the potential capability of providing unconditional security, arbitrated quantum signature (AQS) schemes, whose implementation depends on the participation of a trusted third party, received intense attention in the past decade. Recently, some typical AQS schemes were cryptanalyzed and improved. In this paper, we analyze the security property of some AQS schemes and show that all the previous AQS schemes, no matter whether original or improved, are still insecure in the sense that the messages and the corresponding signatures can be exchanged among different receivers, allowing the receivers to deny having accepted the signature of an appointed message. Some further improved methods on the AQS schemes are also discussed.