A novel encryption scheme for securing biometric templates based on 2D discrete wavelet transform and 3D Lorenz-chaotic system

A novel symmetric image encryption-then-transmission system based on optical chaos using semiconductor lasers is proposed. In this paper, with identical chaotic injection from a master laser, two slave lasers (SL1 and SL2) can output similar chaotic signals served as chaotic carrier to transmit image. Meanwhile, the chaotic signal of SL1 can be used to generate the key of the encryption scheme. After employing the three-dimensional (3D) cat map and logistic chaotic map, the positions of image pixels are shuffled, and the relationship between the cipher-image and the plain-image is confused simultaneously. Therefore, the system can resist the common attacks such as statistical attack, differential attack, and brute force attack. Through numerical simulations, the high quality chaos synchronization between SL1 and SL2 is obtained. When the chaos masking technique is adopted, the image encrypted by the proposed encryption scheme can be successfully transmitted and decrypted in a 10 km single mode fiber channel from SL1 to SL2, which is accompanied by a bit error rate of less than ${\rm{6.18\,\times \,10}}^{- 19}$ . Exhaustive tests about security analysis are carried out, demonstrating the valuable feasibility and high security of the image encryption-then-transmission system.

This work presents the employment of graph theory for cryptographic applications. A Cartesian product graph (CPG) is used to propose new symmetric encryption schemes. On proposed encryption schemes, the ciphertexts of the plaintexts are sent to the receiver entity as the CPGs. The CPG is created based on two graphs G and H that are generated depending on the random choices of the plaintext bits. These bits are used as vertices of graphs G and H. The purpose of using the CPG is to increase the security level of the symmetric encryption schemes in comparison with other encryption schemes. Two study cases of the proposed symmetric Cartesian product graphic encryption (SCPGE) schemes are presented as new experimental results. The security issues of the proposed SCPGE schemes are determined. The SCPGE schemes consider as new insights for more secure communications.

Security analysis and improvement of some biometric protected templates based on Bloom filters

Nowadays, diagnosing patient diseases remotely is a routine and digital medical images analysis as a part of Telecare Medical Information Systems (TMIS) play a fundamental role in early diagnosing and treating most common and serious diseases such as breast cancer. In this context, altering or distorting even a single pixel of a medical image during its transmission over an unsure channel could lead to a wrong diagnosis and harm patient health, induce damaging delays. Therefore the security and privacy of the transmitted medical images must be addressed most seriously. Several techniques are proposed in the literature to address these issues using different techniques such as chaos theory, more recently, elliptic curves cryptography (ECC) or improved classical methods such as linear cryptography. In this paper, we address the security level concern of an image encryption technique combining ECC with Hill cipher (ECCHC) which has been recently proposed by Dawahdeh et al [13]. Our study rises concerns about some weaknesses and flaws of the analyzed encryption scheme against some plain-text and known plain-text attacks. In addition, and not least issue, it is found that the key length used in Dawahdeh et al. scheme is not sufficiently large to be robust against brute force attack. To fix the found flaws and to improve the encryption scheme, a generalized cryptosystem is suggested. In the enhanced version, the key matrix negotiation is redefined to a cipher that combines a modified EC Integrated Encryption Scheme (ECIES) and the linear multiplication matrix is generalized to key matrix of (2n × 2n), n > 2 to counter efficiently the exhaustive search attack. The effectiveness of the proposed version is evaluated and verified through extensive experimentation and most recent available security tools. Compared with the state-of-the art techniques, the proposed version exhibits excellent security features and can resist to various knowing attacks.

Deployments of biometric technologies are already widely disseminated, i.e. the protection of biometric reference data becomes vital in order to safeguard individuals' privacy. Biometric template protection techniques are designed to protect biometric templates in an irreversible and unlinkable manner (ISO/IEC IS 24745). In addition, these schemes are required to maintain key system properties, e.g. biometric performance or authentication speed. Recently, template protection schemes based on Bloom filters have been introduced and applied to various biometric characteristics, such as iris or face. While a Bloom filter-based representation of biometric templates is irreversible the originally proposed system has been exposed to be vulnerable to cross-matching attacks. In this paper we address this issue and demonstrate that any kind of Bloom filter-based representation of biometric templates can be transformed to an unordered set of integer values which enables a locking of irreversible templates in a fuzzy vault scheme from Dodis et al. which can be secured against known cross-matching attacks. In addition, experiments which are carried out on a publicly available iris database, show that the proposed scheme retains the biometric performance of the original system.

It is known that chaotic, especially hyperchaotic system can be suitable for the application in image encryption owing to itself characteristics. While currently, certain improved chaotic or hyperchaotic systems are confronted with the security issue of encryption due to their less complex dynamical behaviors. To address the problem well, we introduce a novel two-dimensional (2D) crossed hyperchaotic map which is based on the logistic map and the infinite collapse map. The analysis of phase diagram and Lyapunov exponential spectrum demonstrate that the given system can exhibit extensive hyperchaotic behavior and good traversal properties. Moreover, the growing use of digital images has prompted demand for multi-image encryption scheme. For this reason, based on the given 2D crossed hyperchaotic map, a multiple image encryption (MIE) scheme that employs a cross-plane with the operation of simultaneous permutation and diffusion to modify the values of its positions and pixels across multiple images is proposed. A pixel blur preprocessing technique is introduced such that the efficiency of key calculation and the speed and safety of information encryption are greatly improved. Eventually, some simulation examples and security analysis reveal that the put forward encryption scheme is able to keep out kinds of attacks such as the selective plaintext attacks and data loss.

In this chapter, the great sensitivity of nonlinear systems, and especially of chaotic systems, on the initial conditions and on the variation of their parameters, was used to design a novel image encryption scheme. Until now, a great number of chaotic autonomous continuous systems or discrete dynamical systems, have been used in various image encryption processes, as a source of random numbers. However, in this work, a Chaotic Random Bit Generator (CRBG), which is based on a non-autonomous dynamical system, is used. For ridding from the system the influence of the external source and increasing the security of the proposed generator, the Poincar\(\acute{e}\) section for sampling the signal has been used. As a dynamical system, the very well-known Duffing–van der Pol system has been chosen, presenting very good statistical results. The aforementioned CRBG is the “heart” of the proposed image encryption scheme. Finally, the security analysis of the proposed encryption scheme, based on histogram analysis, correlation of two adjacent pixels, differential analysis and information entropy, demonstrate the robustness of the proposed chaotic encryption scheme against all kinds of statistical, cryptanalytic, and brute-force attacks.

In this paper, a novel image encryption algorithm based on a new permutation scheme and DNA operations are introduced. In our algorithm, SHA 256 and DNA hamming distance participate in the generation of the initial conditions of the 4D chaotic system, which can associate the encryption system with the original image. In the permutation process, based on the adjustment process of the IAVL (improved balanced binary tree), a new scrambling algorithm is constructed. Then the dynamic block coding rules are designed, in which different image blocks have different coding rules. In the diffusion process, a new diffusion algorithm with intra-block and inter-block is proposed to perform DNA operations on the intermediate encryption result and the key matrix. In the security analysis, the key space of the encryption system is 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">933</sup> and the information entropy is about 7.9973. In addition, the NPCR and UACI in the differential attack test are close to the ideal values of 99.6094% and 33.4653%. To further prove the security of the encryption algorithm, the Irregular deviation, Maximum deviation, Energy, Contrast, and Homogeneity tests are introduced into the analysis. Experimental results illustrate that the encryption scheme can against multiple illegal attacks like statistical, brute-force and differential attacks.

The security of information and personal privacy are the growing concerns in today’s human life worldwide. The storage of biometric data in the database has raised the prospect of compromising the database leading to grave risks and misuse of the person’s privacy such as growth in terrorism and identity fraud. When a person’s biometric data stored is revealed, their security and privacy are being compromised. This research described a detailed evaluation on several outbreaks and threats associated with the biometric technology. It analyzed the user’s fear and intimidations to the biometric technology alongside the protection steps for securing the biometric data template in the database. It is known that, when somebody’s biometric data template is compromised from the database that consequently might indicate proof of identity robbery of that person. Mixed method to compute and articulate the results as well as a new tactic of encryption-decryption algorithm with a design pattern of Model View Template (MVT) are used for securing the biometric data template in the database. The model managed information logically, the view indicated the visualization of the data, and the template directed the data migration into pattern object. Factors influencing fear of biometric technology such as an exposer of personal information, improper data transfer, and data misuse are found. Strong knowledge of the ideal technology like the private skills of the biometric technology, data secrecy and perceived helpfulness are established. The fears and attacks along the technology like a counterfeit of documents and brute-force attack are known. The designed algorithm based on the cryptographic module of the Fernet keys instance are utilized. The Fernet keys are combined to generate a multiFernet key, integrated with biometric data to produce two encrypted files (byte and text file). These files are incorporated with Twilio message and firmly stored in the database. The storage database has security measures that guard against an impostor’s attack. The database system can block the attacker from unauthorized access. Thus, significantly increased individual data privacy and integrity.

Biometric cryptosystems provide an innovative solution for cryptographic key generation, encryption as well as biometric template protection. Besides high authentication accuracy, a good biometric cryptosystem is expected to protect biometric templates effectively, which requires that helper data does not reveal significant information about the templates. Previous works predominantly follow an appropriate entropy definition to measure the security of biometric cryptosystems. In this paper, we point out limitations of entropy-based security analysis and propose a new security analysis framework that combines information-theoretic approach with computational security. In addition, we construct a fingerprint-based multibiometric cryptosystem (MBC) using decision level fusion. Hash functions are employed in our construction to further protect each single biometric trait. The experimental results and security analysis demonstrate that the proposed MBC provides stronger security and better authentication accuracy compared with a cryptosystem based on single biometric.

The task of searchable encryption schemes in multi-user setting is to handle the problem of dynamical user injection and revocation with consideration of feasibility. Especially, we have to make sure that user revocation will not cause security problem, such as leakage of secret key. Recently, fine-grained access control using trusted third party is proposed to resolve this issue. However, it increases the management complexity for maintaining massive authentication information of users. We present a new concept of coarse-grained access control for the first time and use it to construct a multi-user searchable encryption model in hybrid cloud. In our construction, there are two typical schemes, one is broadcast encryption (BE) scheme to simplify access control, the other is a single-user searchable encryption scheme, which supports two-phases operation and is secure when untrustful server colludes with the adversary. Moreover, we implement such a practical scheme using an improved searchable symmetric encryption scheme, and security analysis support our scheme.

In order to resist eavesdropper collusion attack in wireless multi-user network, the authors propose a distributed physical layer encryption (DPLE) scheme with energy-efficient design. The encryption is embedded into rateless coding at both user nodes and relay node. Meanwhile, data frame permutation is added at the relay for increasing randomness. It is noteworthy that the secret key is used as the seed of random number generator, which controls the encoding process and permutation. At receiver, the decryption is united with decoding process without any extra cost, which makes DPLE special in the field of lightweight security. There are two cases considered in security analysis for resisting collusion attack: without error and with error. Typical results are time complexity and attack success probability, respectively. Furthermore, the evaluation for algorithm implementation is investigated. The theoretic result and simulation show that the proposed scheme can combat colluding eavesdroppers by high complexity and very low attack success probability. Moreover, lower computation cost is achieved.

The widespread deployment of biometric systems has raised public concern about security and privacy of personal data. In this paper, we present a novel framework for biometric template security in multimodal biometric authentication systems based on error correcting codes. Biometric recognition is formulated as a channel coding problem with noisy side information at the decoder based on distributed source coding principles. It is shown that the proposed method binds the biometric template in a cryptographic key which does not reveal any information about the original biometric data even if it is compromised by an attacker. Furthermore, the advantages of the proposed method in terms of security and impact on matching accuracy are discussed. We assess the performance of the proposed method in the context of HUMABIO, an EU Specific Targeted Research Project, where face and gait biometrics are employed in an unobtrusive application scenario for human authentication. Experimental evaluation on a multimodal biometric database demonstrates the validity of the proposed method.

Medical image encryption based on improved ElGamal encryption technique

A novel chaotic encryption scheme based on efficient secret keys and confusion technique for confidential of DICOM images