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Biometric security is a prominent research area with growing privacy and security concerns related to biometric data, generally known as biometric templates. Among the recently proposed biometric template protection schemes, fuzzy commitment is the most popular and reliable. It uses error correcting codes to deal with the significant number of bit errors present in the biometric templates. The high error correcting capability of the underlying error correcting codes is crucial to achieving the desired recognition performance in the biometric system. In general, it is satisfied by padding the input biometric template with some additional bits. The fixed padding approaches proposed in the literature have security vulnerabilities that could disclose the user’s biometric data to the attacker, leading to an impersonation attack. We propose a user-specific, random padding scheme that preserves the recognition performance of the system while it prevents the impersonation attack. The empirical results show that the proposed scheme provides 3 times better recognition performance on the IIT Delhi iris database than the baseline, unprotected systems. Through security analysis, we show that the attack complexity of our proposed work is 2 k, where k is the length of the secret message used to generate codeword, with k≥ 128 bits. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.

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Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

On Security of Fuzzy Commitment Scheme for Biometric Authentication

Fraudulent Resource Consumption (FRC) attacks can be synthesized by subtly consuming metered resources of the cloud servers over a sustained period of time. The objective of the attacker in such attacks is to exploit the utility pricing model by fraudulently consuming cloud resources. This skillful over-consumption of resources results in a considerable financial burden to the client. These attacks are characterized by low-intensity HTTP requests per hour, akin to requests by legitimate users. Hence, the attack requests differ in intent but not in content, which makes FRC attacks hard to detect. In this paper, we propose P-estimation detection scheme to effectively detect these attacks. This is accomplished by training several deep learning LSTM models based on the web server logs. An estimate of attack percentage is calculated and then used to deploy the appropriate detection model. This technique takes into account the dynamic nature of websites where the popularity of web pages can change with time, by retraining and updating the detection models periodically. To the best of the authors’ knowledge, this technique outperforms all the existing FRC detection techniques with a False Negative Rate (FNR) and False Positive Rate (FPR) of 0.0059\% and 0.0\% respectively. The proposed technique is able to detect attacks as low as 2\% intensity. In addition to the detection scheme, this paper also delivers a mitigation and attribution technique to identify such attackers and block them. © 2020 Elsevier Ltd

Journal of Information Security and Applications

Detection and mitigation of fraudulent resource consumption attacks in cloud using deep learning approach

We introduce the notion of TMPS: Ticket-Mediated Password Strengthening, a technique for allowing users to derive keys from passwords while imposing a strict limit on the number of guesses of their password any attacker can make, and strongly protecting the users’ privacy. We describe the security requirements of TMPS, and then a set of efficient and practical protocols to implement a TMPS scheme, requiring only hash functions, CCA2-secure encryption, and blind signatures. We provide several variant protocols, including an offline symmetric-only protocol that uses a local trusted computing environment, and online variants that use group signatures or stronger trust assumptions instead of blind signatures. We formalize the security of our scheme by defining an ideal functionality in the Universal Composability (UC) framework, and by providing game-based definitions of security. We prove that our protocol realizes the ideal functionality in the random oracle model (ROM) under adaptive corruptions with erasures, and prove that security with respect to the ideal/real definition implies security with respect to the game-based definitions. © Springer Nature Switzerland AG 2020.

TMPS: Ticket-mediated password strengthening

The widespread deployment of multi-biometrics to authenticate users prompts the need for biometric systems with high recognition performance. Further, the biometric data, once leaked or stolen, remains compromised forever. Hence biometric security is of utmost importance. Existing biometric template protection schemes either degrade the recognition performance or they have issues with security and speed. We propose a cancelable multi-biometric authentication approach where a novel bit-wise encryption scheme transforms a biometric template to a protected template using a secret key generated from another biometric template. It fully preserves the number of bit-errors in the original and the protected template to ensure recognition performance equivalent to the performance of the unprotected systems. We introduce Algorithm I and Algorithm II for bit-wise encryption; both are defined over cryptographic-primitives- block cipher based encryption and keyed-hash function. We profile these algorithms on various hardware architectures to calculate the efficiency in terms of the time taken during enrolment and authentication phase. For Algorithm II, we observe that a 3.3 GHz desktop architecture takes about 18 milliseconds on an average of over 200 runs to authenticate a user. Additionally, we provide mathematical proof to show that the proposed scheme guarantees secrecy and irreversibility. The results of comparisons with the existing biometric template protection schemes on the various face and iris databases show that the proposed work provides significantly good recognition performance and efficiency, while it achieves high security. Finally, the bit-wise encryption scheme can be built over the commercial-off-the-shelf systems to achieve security with equivalent high performance. © 2005-2012 IEEE.

IEEE Transactions on Information Forensics and Security

Cancelable Multi-Biometric Approach Using Fuzzy Extractor and Novel Bit-Wise Encryption

Increasing threat of password leakage from compromised password hashes demands a resource consuming password-hashing algorithm to prevent the precomputation of the password hashes. A class of password-hashing schemes (PHS) provides such a defense by making the design Memory hard. This ensures that any reduction in the memory consumed by the algorithm leads to an exponential increase in its runtime. The security offered by a memory-hard PHS design is measured in terms of its time–memory trade-off (TMTO) defense. Another important measure for a good PHS is its efficiency in utilizing all the available memory as quickly as possible, and fast running time when more than the required memory is available. In this work, we present a simple technique to analyze TMTO for a password-hashing scheme which can be represented as a directed acyclic graph (DAG). The nodes of the DAG correspond to the storage required by the algorithm and the edges correspond to the flow of the execution. Our proposed technique provides expected runtimes at varied levels of available storage utilizing the DAG representation of the algorithm. We show the effectiveness of our proposed technique by applying it on three designs from the “Password Hashing Competition" (PHC)—Argon2-Version 1.2.1 (the PHC winner), Catena-Version 3.2 and Rig-Version 2. Our analysis shows that Argon2i is not providing expected memory hardness which is also highlighted in a recent work by Corrigan-Gibbs et al. We analyze these PHS for performance under various settings of time and memory complexities. Our experimental results show (i) simple DAGs for PHS are efficient but not memory hard, (ii) complex DAGs for PHS are memory hard but less efficient, and (iii) combination of two simple graphs in the representation of a DAG for PHS achieves both memory hardness and efficiency. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.

International Journal of Information Security

Cryptanalytic time–memory trade-off for password hashing schemes

Breach in password databases has been a frequent phenomena in the software industry. Often these breaches go undetected for years. Sometimes, even the companies involved are not aware of the breach. Even after they are detected, publicizing such attacks might not always be in the best interest of the companies. This calls for a strong breach detection mechanism. Juels et al. (in ACM-CCS 2013) suggest a method called ‘Honeywords’, for detecting password database breaches. Their idea is to generate multiple fake passwords, called honeywords and store them along with the real password. Any login attempt with honeywords is identified as a compromise of the password database, since legitimate users are not expected to know the honeywords corresponding to their passwords. The key components of their idea are (i) generation of honeywords, (ii) typo-safety measures for preventing false alarms, (iii) alarm policy upon detection, and (iv) testing robustness of the system against various attacks. In this work, we analyze the limitations of existing honeyword generation techniques. We propose a new attack model called ‘Multiple System Intersection attack considering Input’. We show that the ‘Paired Distance Protocol’ proposed by Chakraborty et al., is not secure in this attack model. We also propose new and more practical honeyword generation techniques and call them the ‘evolving-password model’, the ‘user-profile model’, and the ‘append-secret model’. These techniques achieve ‘approximate flatness’, implying that the honeywords generated using these techniques are indistinguishable from passwords with high probability. Our proposed techniques overcome most of the risks and limitations associated with existing techniques. We prove flatness of our ‘evolving-password model’ technique through experimental analysis. We provide a comparison of our proposed models with the existing ones under various attack models to justify our claims.

Fulltext

IEEE Transactions on Dependable and Secure Computing

Generation of Secure and Reliable Honeywords, Preventing False Detection

Password Hashing, a technique commonly implemented by a server to protect passwords of clients, by performing a one-way transformation on the password, turning it into another string called the hashed password. In this paper, we introduce a secure password hashing framework Rig which is based on secure cryptographic hash functions. It provides the flexibility to choose different functions for different phases of the construction. The design of the scheme is very simple to implement in software and is flexible as the memory parameter is independent of time parameter (no actual time and memory trade-off) and is strictly sequential (difficult to parallelize) with comparatively huge memory consumption that provides strong resistance against attackers using multiple processing units. It supports client-independent updates, i.e., the server can increase the security parameters by updating the existing password hashes without knowing the password. Rig can also support the server relief protocol where the client bears the maximum effort to compute the password hash, while there is minimal effort at the server side. We analyze Rig and show that our proposal provides an exponential time complexity against the low-memory attack. © Springer International Publishing Switzerland 2015.

Rig: A simple, secure and flexible design for password hashing

Password Hashing is the technique of performing one-way transformation of the password. One of the requirements of password hashing algorithms is to be memory demanding to provide defense against hardware attacks. In practice, most Cryptographic designs are implemented inside a Cryptographic module, as suggested by NIST in a set of standards (FIPS 140). A cryptographic module has a limited memory and this makes it challenging to implement a password hashing scheme (PHS) inside it. In this work, we propose a novel approach to allow a limited memory cryptographic module to be used in the implementation of a high memory password hashing algorithm. We also analyze all the first round entries of the Password Hashing Competition (PHC) to evaluate the suitability of the submitted algorithms to be implemented with a Cryptographic module. We graphically show that the submissions to the PHC can be securely implemented in a crypto-module following our suggestion. To the best of our knowledge, this is the first attempt in the direction of secure implementation of password hashing algorithms. © Springer International Publishing Switzerland 2015.

Cryptographic module based approach for password hashing schemes

Tweakable block ciphers are important primitives for designing cryptographic schemes with high security. In the absence of a standardized tweakable block cipher, constructions built from classical block ciphers remain an interesting research topic in both theory and practice. Motivated by Mennink's F[2] publication from 2015, Wang et al. proposed 32 optimally secure constructions at ASIACRYPT'16, all of which employ two calls to a classical block cipher each. Yet, those constructions were still limited to n-bit keys and n-bit tweaks. Thus, applications with more general key or tweak lengths still lack support. This work proposes the XHX family of tweakable block ciphers from a classical block cipher and a family of universal hash functions, which generalizes the constructions by Wang et al. First, we detail the generic XHX construction with three independently keyed calls to the hash function. Second, we show that we can derive the hash keys in efficient manner from the block cipher, where we generalize the constructions by Wang et al.; finally, we propose efficient instantiations for the used hash functions.