Cryptography
http://www.mdpi.com/journal/cryptography
Latest open access articles published in Cryptography at http://www.mdpi.com/journal/cryptography<![CDATA[Cryptography, Vol. 1, Pages 10: Password-Hashing Status]]>
http://www.mdpi.com/2410-387X/1/2/10
Computers are used in our everyday activities, with high volumes of users accessing provided services. One-factor authentication consisting of a username and a password is the common choice to authenticate users in the web. However, the poor password management practices are exploited by attackers that disclose the users’ credentials, harming both users and vendors. In most of these occasions the user data were stored in clear or were just processed by a cryptographic hash function. Password-hashing techniques are applied to fortify this user-related information. The standardized primitive is currently the PBKDF2 while other widely-used schemes include Bcrypt and Scrypt. The evolution of parallel computing enables several attacks in password-hash cracking. The international cryptographic community conducted the Password Hashing Competition (PHC) to identify new efficient and more secure password-hashing schemes, suitable for widespread adoption. PHC advanced our knowledge of password-hashing. Further analysis efforts revealed security weaknesses and novel schemes were designed afterwards. This paper provides a review of password-hashing schemes until the first quarter of 2017 and a relevant performance evaluation analysis on a common setting in terms of code size, memory consumption, and execution time.Cryptography2017-06-2712Article10.3390/cryptography1020010102410-387X2017-06-27doi: 10.3390/cryptography1020010George Hatzivasilis<![CDATA[Cryptography, Vol. 1, Pages 9: Cryptanalysis and Improvement of ECC Based Authentication and Key Exchanging Protocols]]>
http://www.mdpi.com/2410-387X/1/1/9
Elliptic curve cryptography (ECC) is extensively used in various multifactor authentication protocols. In this work, various recent ECC-based authentication and key exchange protocols are subjected to threat modeling and static analysis to detect vulnerabilities and to enhance them to be more secure against threats. This work demonstrates how currently-used ECC-based protocols are vulnerable to attacks. If protocols are vulnerable, damage could include critical data loss and elevated privacy concerns. The protocols considered in this work differ in their usage of security factors (e.g., passwords, pins and biometrics), encryption and timestamps. The threat model considers various kinds of attacks including denial of service, man in the middle, weak authentication and SQL injection. Countermeasures to reduce or prevent such attacks are suggested. Beyond cryptanalysis of current schemes and the proposal of new schemes, the proposed adversary model and criteria set forth provide a benchmark for the systematic evaluation of future two-factor authentication proposals.Cryptography2017-06-1311Article10.3390/cryptography101000992410-387X2017-06-13doi: 10.3390/cryptography1010009Swapnoneel RoyChanchal Khatwani<![CDATA[Cryptography, Vol. 1, Pages 8: Analysis of Entropy in a Hardware-Embedded Delay PUF]]>
http://www.mdpi.com/2410-387X/1/1/8
The magnitude of the information content associated with a particular implementation of a Physical Unclonable Function (PUF) is critically important for security and trust in emerging Internet of Things (IoT) applications. Authentication, in particular, requires the PUF to produce a very large number of challenge-response-pairs (CRPs) and, of even greater importance, requires the PUF to be resistant to adversarial attacks that attempt to model and clone the PUF (model-building attacks). Entropy is critically important to the model-building resistance of the PUF. A variety of metrics have been proposed for reporting Entropy, each measuring the randomness of information embedded within PUF-generated bitstrings. In this paper, we report the Entropy, MinEntropy, conditional MinEntropy, Interchip hamming distance and National Institute of Standards and Technology (NIST) statistical test results using bitstrings generated by a Hardware-Embedded Delay PUF called HELP. The bitstrings are generated from data collected in hardware experiments on 500 copies of HELP implemented on a set of Xilinx Zynq 7020 SoC Field Programmable Gate Arrays (FPGAs) subjected to industrial-level temperature and voltage conditions. Special test cases are constructed which purposely create worst case correlations for bitstring generation. Our results show that the processes proposed within HELP to generate bitstrings add significantly to their Entropy, and show that classical re-use of PUF components, e.g., path delays, does not result in large Entropy losses commonly reported for other PUF architectures.Cryptography2017-06-0711Article10.3390/cryptography101000882410-387X2017-06-07doi: 10.3390/cryptography1010008Wenjie CheVenkata KajuluriMitchell MartinFareena SaqibJim Plusquellic<![CDATA[Cryptography, Vol. 1, Pages 7: Maximum-Order Complexity and Correlation Measures]]>
http://www.mdpi.com/2410-387X/1/1/7
We estimate the maximum-order complexity of a binary sequence in terms of its correlation measures. Roughly speaking, we show that any sequence with small correlation measure up to a sufficiently large order k cannot have very small maximum-order complexity.Cryptography2017-05-1311Article10.3390/cryptography101000772410-387X2017-05-13doi: 10.3390/cryptography1010007Leyla IşıkArne Winterhof<![CDATA[Cryptography, Vol. 1, Pages 6: Garbled Quantum Computation]]>
http://www.mdpi.com/2410-387X/1/1/6
The universal blind quantum computation protocol (UBQC) enables an almost classical client to delegate a quantum computation to an untrusted quantum server (in the form of a garbled quantum circuit) while the security for the client is unconditional. In this contribution, we explore the possibility of extending the verifiable UBQC, to achieve further functionalities following the analogous research for classical circuits (Yao 1986). First, exploring the asymmetric nature of UBQC (the client preparing only single qubits, while the server runs the entire quantum computation), we present a “Yao”-type protocol for secure two-party quantum computation. Similar to the classical setting, our quantum Yao protocol is secure against a specious (quantum honest-but-curious) garbler, but in our case, against a (fully) malicious evaluator. Unlike the previous work on quantum two-party computation of Dupuis et al., 2010, we do not require any online-quantum communication between the garbler and the evaluator and, thus, no extra cryptographic primitive. This feature will allow us to construct a simple universal one-time compiler for any quantum computation using one-time memory, in a similar way to the classical work of Goldwasser et al., 2008, while more efficiently than the previous work of Broadbent et al., 2013.Cryptography2017-04-0711Article10.3390/cryptography101000662410-387X2017-04-07doi: 10.3390/cryptography1010006Elham KashefiPetros Wallden<![CDATA[Cryptography, Vol. 1, Pages 5: Privacy in a Digital, Networked World: Technologies, Implications and Solutions. By Sherali Zeadally and Mohamad Badra. Springer International Publishing: 418 pp.; $51.89; ISBN-10: 3319084690, ISBN-13: 978-3319084695]]>
http://www.mdpi.com/2410-387X/1/1/5
n/aCryptography2017-03-1911Book Review10.3390/cryptography101000552410-387X2017-03-19doi: 10.3390/cryptography1010005Nicolas Sklavos<![CDATA[Cryptography, Vol. 1, Pages 4: Cryptography in Wireless Multimedia Sensor Networks: A Survey and Research Directions]]>
http://www.mdpi.com/2410-387X/1/1/4
Wireless multimedia sensor networks will play a central role in the Internet of Things world, providing content-rich information for an uncountable number of monitoring and control scenarios. As more applications rely on multimedia data, security concerns gain attention, and new approaches arise to provide security for such networks. However, the usual resource constraints of processing, memory and the energy of multimedia-based sensors have brought different challenges for data encryption, which have driven the development of different security approaches. In this context, this article presents the state-of-the-art of cryptography in wireless multimedia sensor networks, surveying innovative works in this area and discussing promising research directions.Cryptography2017-01-0511Review10.3390/cryptography101000442410-387X2017-01-05doi: 10.3390/cryptography1010004Daniel CostaSolenir FiguerêdoGledson Oliveira<![CDATA[Cryptography, Vol. 1, Pages 3: A Privacy-Preserving, Mutual PUF-Based Authentication Protocol]]>
http://www.mdpi.com/2410-387X/1/1/3
This paper describes an authentication protocol using a Hardware-Embedded Delay PUF called HELP. HELP derives randomness from within-die path delay variations that occur along the paths within a hardware implementation of a cryptographic primitive, such as AES or SHA-3. The digitized timing values which represent the path delays are stored in a database on a secure server (verifier) as an alternative to storing PUF response bitstrings. This enables the development of an efficient authentication protocol that provides both privacy and mutual authentication. The security properties of the protocol are analyzed using data collected from a set of Xilinx Zynq FPGAs.Cryptography2016-11-2511Article10.3390/cryptography101000332410-387X2016-11-25doi: 10.3390/cryptography1010003Wenjie CheMitchell MartinGoutham PocklasseryVenkata KajuluriFareena SaqibJim Plusquellic<![CDATA[Cryptography, Vol. 1, Pages 2: Balanced Permutations Even–Mansour Ciphers]]>
http://www.mdpi.com/2410-387X/1/1/2
The r-rounds Even–Mansour block cipher is a generalization of the well known Even–Mansour block cipher to r iterations. Attacks on this construction were described by Nikolić et al. and Dinur et al. for r = 2 , 3 . These attacks are only marginally better than brute force but are based on an interesting observation (due to Nikolić et al.): for a “typical” permutation P, the distribution of P ( x ) ⊕ x is not uniform. This naturally raises the following question. Let us call permutations for which the distribution of P ( x ) ⊕ x is uniformly “balanced” — is there a sufficiently large family of balanced permutations, and what is the security of the resulting Even–Mansour block cipher? We show how to generate families of balanced permutations from the Luby–Rackoff construction and use them to define a 2 n -bit block cipher from the 2-round Even–Mansour scheme. We prove that this cipher is indistinguishable from a random permutation of { 0 , 1 } 2 n , for any adversary who has oracle access to the public permutations and to an encryption/decryption oracle, as long as the number of queries is o ( 2 n / 2 ) . As a practical example, we discuss the properties and the performance of a 256-bit block cipher that is based on our construction, and uses the Advanced Encryption Standard (AES), with a fixed key, as the public permutation.Cryptography2016-04-0111Article10.3390/cryptography101000222410-387X2016-04-01doi: 10.3390/cryptography1010002Shoni GilboaShay GueronMridul Nandi<![CDATA[Cryptography, Vol. 1, Pages 1: Cryptography: A New Open Access Journal]]>
http://www.mdpi.com/2410-387X/1/1/1
Cryptography has very long history, from ancient ciphers, such as Ceaser cipher, machine (or rotor) cipherx during WWI and WWII, and modern ciphers, which play a fundamental role in providing Confidentiality, Integrity, and Authentication services during transmission, processing, and storage of the sensitive data over the open or public networks. [...]Cryptography2016-02-1511Editorial10.3390/cryptography101000112410-387X2016-02-15doi: 10.3390/cryptography1010001Kwangjo Kim