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Hierarchical identity-based encryption is an important extension from IBE and has found many applications in the network world. Private key revocation is a crucial requirement for any public key system. In this paper, we propose a novel revocation method for the hierarchical identity-based encryption. Existing revocable hierarchical identity-based encryption schemes have several disadvantages: the key update size increases logarithmically with the number of users in the system, the public information of key update received by each user is different and always related to the level of the identity hierarchy and the security proof of the revocable scheme is very complex. In our scheme, cryptographic accumulators are used to compress hierarchical levels and revoked users’ information into constant values. So we achieve almost constant size of private key update which is irrelevant with the user number in the system. Because of the compression of hierarchical information we can use simple dual system encryption techniques to prove our scheme to be fully secure under several common assumptions without resorting to complex nested dual system encryption techniques.

One of the interesting secure applications in the smart city is broadcasting information to legitimate users, desirably with user privacy. Broadcast encryption has been considered as a useful tool to protect the data security and provide data access control. Most works in broadcast encryption are about the data security, while less attention is paid to the data access control and the identity privacy. In this paper, based on broadcast encryption, we present a scheme called Fully Privacy-Preserving and Revocable Identity-Based Broadcast Encryption, which preserves the data privacy and the identity privacy of the receiver as well as the revoked user. The data can be securely protected and only the authorized user can access the data. The revocation process does not reveal any information about the data contents and the receiver identity. The public learns nothing about the receiver identity and the revoked user identity. These properties lead to nice applications in the smart city where identity privacy is desirable. The security of our scheme is proved to be semantically secure in the random oracle model.

More and more sensitive information is transmitted and stored in computer networks. Security has become a critical issue. As traditional cryptographic systems are now vulnerable to attacks, DNA based cryptography has been identified as a promising technology because of the vast parallelism and extraordinary information density. While a body of research has proposed the DNA based encryption algorithm, no research has provided solutions to distribute complex and long secure keys. This paper introduces a Hamming code and a block cipher mechanism to ensure secure transmission of a secure key. The research overcomes the limitation on the length of the secure key represented by DNA strands. Therefore it proves that real biological DNA strands are useful for encryption computing. To evaluate our method, we apply the block cipher mechanism to optimize a DNA-based implementation of a conventional symmetric encryption algorithm, described as “yet another encryption algorithm”. Moreover, a maximum length matching algorithm is developed to provide immunity against frequency attacks.

Multimedia is currently seen to dominate the internet network and the mobile network traffic; hence, it is seen as the largest Big data. Generally, the symmetric encryption algorithms are applied to the ‘big multimedia data’; however; these algorithms are thought as very slow. In our study, we developed and designed a resource-efficient encryption algorithm system which applies the multithreaded programming process for the encryption of the big multimedia data. This proposed system describes a multi-level encryption model which uses the Feistel Encryption Scheme, genetic algorithms and the Advanced Encryption Standard (AES). Our system has been assessed for actual medical-based big multimedia data and compared to the benchmarked encryption algorithms like the RC6, MARS, 3-DES, DES, and Blowfish with regards to the computational run time and its throughput for the encryption and decryption procedures. In addition, the multithreaded programming approach is adopted to implement the proposed encryption system in order to enhace the system effeciencey and porfermance. Furthermore, we also compared our system with its sequential version for showing its resource efficiency. Our results indicated that our system had the least run time and a higher throughput for the encryption and decryption processes in comparison to the already existing standard encryption algorithms. Also, our system could improve the computation run time by approximately 75% and its throughput was also increased by 4-times in comparison to its sequential version. For fulfilling the security objectives, our algorithm showed a better Avalanche Effect in comparison to the existing algorithms and therefore, could be included in any encryption/decryption process of a big plain multimedia data.

The secure storage of the sensitive data in mobile devices is an urgent issue. Most of the existed encryption algorithms are location independent, which means the encrypted data can be decrypted anywhere. In this work, we propose a novel location-based encryption model using a fuzzy vault scheme. First, we may choose a proper encryption algorithm, a symmetric algorithm or an asymmetric encryption algorithm, to encrypt the sensitive data in mobile devices. Then, the crucial issue comes to securely storing the secret key in the encryption algorithm, and it will be solved in the secret key protection phase by applying a fuzzy vault scheme using a location-based digital fingerprint, which represents the valid user in the valid location region. We bind the digital fingerprint and the secret key together to construct a fuzzy vault for storing the both securely. We simulate our model on an Android device and make some performance and security analysis on it. The main contribution of our model is applying a fuzzy vault scheme which uses the location information captured by the user’s mobile devices to securely protect the secret key used in the cryptosystem for encrypting the users sensitive data on the user’s mobile devices.

Cloud computing is one of the great tasks in the business world nowadays, which provides shared processing resources. In cloud area network, security is the main challenge faced by cloud providers and their customers. The advantage of cloud computing includes reduced cost, re-provisioning of resources etc. The cloud network makes use of standard encryption method to secure documents while storing in online. In this paper, we have depicted two efficient encryption algorithms that meet security demand in cloud. Probabilistic encryption, one of these algorithms may be used to produce randomness of text encryption. With this algorithm, if the same message is encrypted twice it should yield different secret coded texts on both calculations. Another crucial algorithm is homomorphic encryption, is a cryptographic method to define the sample system and to provide a software implementation. In order to maintain quality of service (QoS) and improve customer satisfaction, we are going to propose an efficient algorithm which combines the characteristics of both probabilistic and homomorphic encryption techniques, to provide high level of security. Our proposed scheme will yield better encryption techniques reduce security attacks, increased throughput and improve the QoS.

We give a new black-box transformation from any semantically secure encryption scheme into a non-malleable one which has a better rate than the best previous work of Coretti et al. (in: Kushilevitz and Malkin (eds) TCC 2016-A, Part I, Springer, Heidelberg, 2016). We achieve a better rate by departing from the "matrix encoding" methodology used by previous constructions, and working directly with a single codeword. We also use a Shamir secret-share packing technique to improve the rate of the underlying error-correcting code.

In order to construct efficient public-key encryption scheme that is secure against adaptive chosen-ciphertext attacks (CCA), an efficient signature scheme and an identity-based encryption (IBE) scheme from the learning with errors over rings are presented firstly in this paper, whose security are reducible to the hardness of the shortest vector problem in the worst case on ideal lattices. Secondly, a CCA-secure public key cryptosystem is constructed on the basis of the IBE and signature proposed above. The efficiency analysis indicates the proposed signature and encryption schemes are much more efficient than correlative cryptosystems. The security analysis shows that the IBE scheme is secure against chosen-plaintext attacks, and the public-key encryption scheme is CCA-secure in the random oracle model.

Nowadays, multimedia is considered to be the biggest big data as it dominates the traffic in the Internet and mobile phones. Currently symmetric encryption algorithms are used in IoT but when considering multimedia big data in IoT, symmetric encryption algorithms incur more computational cost. In this paper, we have designed and developed a resource-efficient encryption system for encrypting multimedia big data in IoT. The proposed system takes the advantages of the Feistel Encryption Scheme, an Advanced Encryption Standard (AES), and genetic algorithms. To satisfy high throughput, the GPU has also been used in the proposed system. This system is evaluated on real IoT medical multimedia data to benchmark the encryption algorithms such as MARS, RC6, 3-DES, DES, and Blowfish in terms of computational running time and throughput for both encryption and decryption processes as well as the avalanche effect. The results show that the proposed system has the lowest running time and highest throughput for both encryption and decryption processes and highest avalanche effect with compared to the existing encryption algorithms. To satisfy the security objective, the developed algorithm has better Avalanche Effect with compared to any of the other existing algorithms and hence can be incorporated in the process of encryption/decryption of any plain multimedia big data. Also, it has shown that the classical and modern ciphers have very less Avalanche Effect and hence cannot be used for encryption of confidential multimedia messages or confidential big data. The developed encryption algorithm has higher Avalanche Effect and for instance, AES in the proposed system has an Avalanche Effect of %52.50. Therefore, such system is able to secure the multimedia big data against real-time attacks.

This paper introduces a secure speech communication approach, which is based on encryption and authentication. This system is based on Advanced Encryption Standard (AES) for encryption and private image database for enhancement of encryption and for authentication. The idea of this cryptosystem is based on XOR of one image from image database with the clear speech before encryption and embedding the index number of this image in the database as a least significant bit watermark into speech. A comparison study is held between the AES block cipher algorithm and the proposed algorithm. This proposed cryptosystem used to enhance the security of AES algorithm and increase its immunity to brute force attacks. It used also to provide authentication and enhance security by addition of extra key which don't need to be exchanged between parts depending on the embedded image. The extra proposed step remove residual intelligibility from clear speech and fill the silent periods within speech conversation and help in destroy format and pitch information. Security analyses are presented for the proposed cryptosystem from a strict cryptographic viewpoint. Experimental results verify and prove that the proposed cryptosystem is highly secure from the cryptographic viewpoint.

The challenge to which the encryption of multimedia data needs to respond is ensuring the security of data intensive video stream in an efficient way. Unlike full data encryption, selective encryption manages to achieve this by encrypting only a part of the data stream, while providing a satisfactory level of video security. This optimizes the processing time and the size of encrypted data. Regardless of the encryption technique, there is a lack of cryptographic synchronization when providing random access to the selected part of the encrypted multimedia stream. In this paper we propose a novel and efficient method of cryptographic synchronization as an extension to the H.265/HEVC crypto encoder in order to support random access in selectively encrypted video stream.

In 2009, Gentry first introduced an ideal lattices fully homomorphic encryption (FHE) scheme. Later, based on the approximate greatest common divisor problem, learning with errors problem or learning with errors over rings problem, FHE has developed rapidly, along with the low efficiency and computational security. Combined with quantum mechanics, Liang proposed a symmetric quantum somewhat homomorphic encryption (QSHE) scheme based on quantum one-time pad, which is unconditional security. And it was converted to a quantum fully homomorphic encryption scheme, whose evaluation algorithm is based on the secret key. Compared with Liang’s QSHE scheme, we propose a more efficient QSHE scheme for classical input states with perfect security, which is used to encrypt the classical message, and the secret key is not required in the evaluation algorithm. Furthermore, an efficient symmetric searchable encryption (SSE) scheme is constructed based on our QSHE scheme. SSE is important in the cloud storage, which allows users to offload search queries to the untrusted cloud. Then the cloud is responsible for returning encrypted files that match search queries (also encrypted), which protects users’ privacy.

With the flourish of applications based on the internet of things and cloud computing, privacy issues have been attracting a lot of attentions. Although the increasing use of full disk encryption (FDE) significantly hamper privacy leakage and digital forensics, cold boot attacks have thwarted FDE since forensic recovery of scrambled telephones (FROST), a forensic tool, is proposed. The cryptographic keys which are stored in the mobile devices are inclined to be obtained by FROST. Recent research results have shown CPU-bound encryption methods to resist FROST. However, these methods performs AES encryption solely on CPU registers, whose advantage comes at the cost of encryption speed. This paper, therefore, presents a cryptographic key protection scheme for android devices which prevents FROST from acquiring the key of AES by changing storage location of the key in memory. The storage location of the key is switched to the fixed position where command line parameters will be stored when android boots. Therefore, the key will be covered by command line parameters while the system reboots, which negates FROST from obtaining the key. Compared with the popular CPU-bound encryption methods, our method has less impact on encryption efficiency and employs no additional storage resources.

Attributed-based encryption (ABE) is a promising cryptographic access control mechanism with a rich expressiveness of ABE policies. Due to the high complexities of encryption and decryption, users are burdened with large computation cost. Fortunately, outsourcing technologies can be used to reduce the computation overhead for the ABE schemes. In the recent decade, the achievements of the outsourced ciphertext-policy ABE (CP-ABE) schemes are inspiring. But, the outsourcing encryption algorithms for CP-ABE schemes are not addressed properly since the encryption exponents are dynamic. In this paper, we present an efficient outsourced CP-ABE scheme with checkability, where the number of the exponential operations in the encryption can be reduced to a constant by introducing a blinding algorithm. Meanwhile, the ciphertext size is not increased. Furthermore, to guarantee the correctness of our scheme, we provide the verification mechanism based on a collision-resistance hash function, which allows the users to efficiently check the validity of messages and outsourced computation results. Besides, the proposed scheme is secure against replayable chosen ciphertext attacks based on Green’s outsourcing security model. Intensive experiments are carried out to illustrate the efficiency of the proposed scheme.

Internet of the things is the most trending topics in the digital world. Security issues are rampant. In the corporate or institutional setting, security risks are apparent from the outset. Market leaders are unable to use the cryptographic techniques due to their complexities. Hence many bits of private information, including ID, are readily available for third parties to see and to utilize. There is a need to decrease the complexity and increase the robustness of the cryptographic approaches. In view of this, a new cryptographic technique as good encryption pact with adjacency, random prime number and quantum code properties has been proposed. Here, encryption can be done by using quantum photons with gray code. This approach uses the concepts of physics and mathematics with no external key exchange to improve the security of the data. It also reduces the key attacks by generation of a key at the party side instead of sharing. This method makes the security more robust than with the existing approach. Important properties of gray code and quantum are adjacency property and different photons to a single bit (0 or 1). These can reduce the avalanche effect. Cryptanalysis of the proposed method shows that it is resistant to various attacks and stronger than the existing approaches.

The security of modern cryptosystems relies on the secrecy of the keys. Against the expectation that the keys used in cryptographic algorithms are perfectly secure, the keys can get compromised when implemented on physical devices. Because of the computational leakages from the execution of cryptographic algorithms, a variety of side-channel measurements can lead to full breaks of the targeted physical devices. Leakage-resilient cryptography aims at defining leakages in a generic model and designing provably secure primitives to capture side-channel attacks. For this purpose, several re-keying schemes are proposed to prevent encryption scheme from using the same key many times. In this paper, we propose a leakage-resilient authenticated encryption scheme, called Re-keying Code Book (RCB), that is secure against the side-channel attacks by combining with existing re-keying schemes. Our approach is to find efficient composition by combining two independent primitives, authenticated encryption, and re-keying schemes, rather than designing new algorithms. We also give the precise definitions of privacy and authenticity for authenticated encryption in a leakage-resilient model, and then, we provide the security proofs for RCB in a leakage-resilient model.

Public key encryption with keyword search plays very important role in the outsourced data management. In most of public key encryption schemes with keyword search, the server can unlimitedly execute keyword search ability after obtaining a trapdoor information of a keyword. To restrict the ability of the server's unlimited search, we propose a novel public key encryption with revocable keyword search by combining hash chain and anonymous multi-receiver encryption scheme in this paper. The scheme can not only achieve security property of the indistinguishability of ciphertexts against an adaptive chosen keywords attack, but also resist off-line keyword guess attack. By comparison with Yu et al.'s scheme, our scheme is more efficient in terms of computational cost and communication overhead for the whole system.

A bit-oriented quantum public-key encryption scheme is presented. We use Boolean functions as private-key and randomly changed pairs of quantum state and classical string as public-keys. Following the concept of quantum perfect encryption, we prepare the public-key with Hadamard transformation and Pauli transformation. The quantum part of public-keys is various with different classical strings. In contrast to the typical classical public-key scheme, one private-key in our scheme corresponds to an exponential number of public-keys. We investigate attack to the private-key and prove that the public-key is a totally mixed state. So the adversary cannot acquire any information about private-key from measurement of the public-key. Then, the attack to encryption is analyzed. Since the trace distance between two different ciphertexts is zero, the adversary cannot distinguish between the two ciphertext states and also obtains nothing about plaintext and private-key. Thus, we have the conclusion that the proposed scheme is information-theoretically secure under an attack of the private-key and encryption.

Wadi and Zainal recently proposed a high definition image encryption algorithm based on a modified AES-128 block cipher in (Wirel Pers Commun 79(2):811---829, 2014). In this paper, we show that the core component of their image encryption algorithm, a modified AES-128 cipher, is insecure against impossible differential attack. The proposed impossible differential attack on the full rounds of the modified AES-128 cipher has a time complexity of around $$2^{88.74}$$288.74 encryptions with $$2^{114.06}$$2114.06 chosen plaintexts and $$2^{99}$$299 bytes of memory, in contrast to the expected security of $$2^{128}$$2128. The existence of such an attack disproves the claims made by the designers that their modified AES-128 cipher improves the security of the AES cipher and that it can subsequently be used to construct a secure image encryption scheme. The root cause of this attack, some other issues with the modified AES cipher and possible solutions are described to serve as important remarks in designing a secure image encryption scheme.

Identity-based encryption with keyword search (IBEKS) is a useful cryptographic primitive for cloud computing, i.e., it allows a data owner to encrypt and store his data in a cloud storage server, and later the owner can use his/her private key to produce a search trapdoor for searching the encrypted data. Existing IBEKS schemes only focus on supporting efficient and complex queries for the private key holder, while the authority, who is in charge of the generation of the private keys for users, cannot efficiently search the encrypted data. However, some applications might require the authority to efficiently search the encrypted data intended for any user. To address this problem, in this paper, we introduce a new primitive named dual trapdoor identity-based encryption with keyword search (DTIBEKS). In this primitive, the authority can use a peculiar way to produce one more trapdoor, which allows the authority to search any identity's encrypted data. We formally give the definition and security model for DTIBEKS, and then propose a novel DTIBEKS scheme. We further prove the security of our proposed DTIBEKS without random oracles. It is worth noting that our scheme can be easily transformed into identity-based encryption with fuzzy keyword search.

Public-key encryption (PKE) can be used in cloud system to protect data in data sharing, identity authentication, etc. However, the security model of traditional PKE does not capture the “key-leakage attacks” which can leak partial information about the secret key. Also, the adversary can inject fault to tamper with the secret key and observe the output of the public key encryption scheme under this modified key which is called “related-key attack”. In this paper, we present a method to construct public key encryption schemes secure against both weak key-leakage attacks and affine related-key attacks directly from extractable hash proof systems. Specifically, we first add Key Homomorphism and Fingerprinting properties to all-but-one (ABO) extractable hash proofs and construct a key encapsulation mechanism scheme secure against related-key attacks via it and thus public key encryption scheme secure against related-key attacks. Also, we prove that if the based ABO-extractable hash proof with Key Homomorphism and Fingerprinting properties is weak leakage-resilient, then the key encapsulation mechanism scheme constructed from it is weak leakage-resilient and related-key attack secure. Moreover, we propose a public key encryption scheme secure against affine related-key attacks based on lattice.

Selective image encryption has a significant importance in many applications as it offers significant savings in computations, cost, and time. Many attempts are exerted for this purpose as the traditional full image encryption/decryption algorithms may be too massive. In this paper, a new technique for selective image encryption is developed. The algorithm is based on a combination between the pseudo random number sequences, Arnold permutation, and the advanced encryption standard technique. The proposed technique is intended to reduce the execution time of the encryption process and increase the robustness of the encrypted image.

Cloud storage is one of the most important applications in our daily lives. User can store their own data into cloud storage and remotely access the saved data. Owing to the social media develops, users can share the digital files to other users, leading to the amount of data growing rapidly and searching abilities necessarily. In the some cases, servers cannot avoid data leakage even if the server provides complete access control. The encrypted data is a best way to resolve this problem but it may eliminate original structure and searching may become impossible. Applying searchable encryption for each receiver may produce messy duplication and occupy the quota of cloud storage from each receiver. User requires keeping their shared documents belonging up to date which are compared with the latest version. To this aim, we thus propose a sharable ID-based encryption with keyword search in cloud computing environment, which enables users to search in data owners’ shared storage while preserving privacy of data. For the performance analysis, we demonstrate the compared resultant with others ID-based or ID-relative encryption. In addition to that, we show the formal proof to verify the security of our proposed.

Searchable encryption is an encryption system which provides confidentiality of stored documents and usability of document search at the same time. Remote cloud storage is the most typical application for searchable encryption. By applying searchable encryption, inside attacks can be prevented fundamentally. Designing searchable encryption which supports various queries--for example, range query, conjunctive keyword query, etc.--is also important for convenience. In this paper, we focus on range query problem. Up to now, only a few results have been proposed, in which the main functions are constructed using public key cryptosystems. Therefore, the amount of computations for encryption and search is large. Furthermore, search time depends on the size of the entire database. We propose a new searchable encryption protocol which is based on a symmetric key encryption and linked chain structure instead of public key-based techniques. The main contribution of the protocol is reducing the computation cost for search remarkably. In reality, the amount of computations depends on the number of documents that are matched to a query instead of the size of the entire database.

Public-key encryption can be used to protect the sensitive data in cloud system with intelligent mobile agents facilitating better services. However, many public-key encryption schemes do not resist the side-channel attacks which can be applied to the encryption instances implemented on a chip or cloud to obtain partial information leakage about the secret states, as the traditional security model of public-key encryption does not capture this kind of attacks. Also, the adversary can inject fault to tamper with the secret key and observe the output of the public-key encryption scheme under this modified key which is called "related-key attacks". Inspired by these, the models of key-leakage attacks and related-key attacks are formalized, respectively. In this paper, we present a method to construct public-key encryption schemes against both weak key-leakage attacks and linear related-key attacks from extractable hash proof systems (EHPS or XHPS). Specifically, we first transform ABOEHPS to weak leakage-resilient ABOEHPS and add Key Homomorphism and Fingerprinting properties to it. Then, based on this new ABOEHPS, we construct weak leakage-resilient adaptive trapdoor relation with these two properties and public-key encryption schemes against both weak key-leakage attacks and linear related-key attacks can be constructed from it. Moreover, we propose a public-key encryption scheme against both adaptive key-leakage attacks and linear related-key attacks.

The use of e-payment system for electronic trade is on its way to make daily life more easy and convenient. Contrarily, there are a number of security issues to be addressed, user anonymity and fair exchange have become important concerns along with authentication, confidentiality, integrity and non-repudiation. In a number of existing e-payment schemes, the customer pays for the product before acquiring it. Furthermore, many such schemes require very high computation and communication costs. To address such issues recently Yang et al. proposed an authenticated encryption scheme and an e-payment scheme based on their authenticated encryption. They excluded the need of digital signatures for authentication. Further they claimed their schemes to resist replay, man-in-middle, impersonation and identity theft attack while providing confidentiality, authenticity, integrity and privacy protection. However our analysis exposed that Yang et al.'s both authenticated encryption scheme and e-payment system are vulnerable to impersonation attack. An adversary just having knowledge of public parameters can easily masquerade as a legal user. Furthermore, we proposed improved authenticated encryption and e-payment schemes to overcome weaknesses of Yang et al.'s schemes. We prove the security of our schemes using automated tool ProVerif. The improved schemes are more robust and more lightweight than Yang et al.'s schemes which is evident from security and performance analysis.

During last few years, transmission of digital multimedia data (images, audios and videos) over Internet, wireless cell phones, television broadcasting etc., has been significantly evolved. The provision of security to store and transmit data with confidentiality, integrity, and authentication for multimedia data over wireless medium is attaining importance these days. Over a few decades, a number of image encryption schemes have been implemented, each with various features, pros and cons. So there is a need to carry out security analysis of these schemes through some standard parameters. In this paper, an effort is being made for comparison of traditional encryption algorithms via some security parameters rather than using just visual inspection. Through these security parameters, one can determine a better and highly secure image encryption scheme. Comparative analysis of Advanced Encryption Standard, Compression Friendly Encryption Scheme, Chaotically Coupled Chaotic Map Encryption Scheme and a Bernoulli Map Based Encryption Scheme are done. Results are finally compiled to conclude the optimum scheme to be used feasibly with high security level.

This paper proposes an advanced encryption of MP3 and MPEG-4 coder with a quality degradation-based security model. For the MP3 audio, the magnitude and phase information of modified discrete cosine transform (MDCT) coefficients is encrypted. DCT coefficients and motion vectors (MVs) are used for the scrambling of the MPEG-4 video. This encryption scheme has a level of security, secures in perception, keeps format compliance, and obtains better time efficiency by reducing the encrypted volumes of multimedia contents. These properties make it practical to incorporate encryption and decryption process into compression and decompression process, and thus suitable for secure A/V transmission or sharing. Experimental results indicate that the proposed technique provides levels of security for a flexible business model and achieves a simple and coding-efficient architecture with no adverse impact on error resilience.

This paper proposes a color image encryption scheme using one-time keys based on crossover operator, chaos and the Secure Hash Algorithm(SHA-2). The (SHA-2) is employed to generate a 256-bit hash value from both the plain-image and the secret hash keys to make the key stream change in each encryption process. The SHA-2 value is employed to generate three initial values of the chaotic system. The permutation-diffusion process is based on the crossover operator and XOR operator, respectively. Experimental results and security analysis show that the scheme can achieve good encryption result through only one round encryption process, the key space is large enough to resist against common attacks,so the scheme is reliable to be applied in image encryption and secure communication.

Selective image encryption has been considered as an effective method to improve the encryption speed and computation resource by reducing considerable amount of data. In the present paper, the weaknesses of recent method of selective image encryption are presented analytically and the method of security improvement is proposed. The security for selective image encryption is improved in a way that number of selectively significant bits for encryption vary from pixel to pixel. This leads to be uncertain data for encryption and decryption. The examples are to demonstrate and verify for security weaknesses of the recent method and the effectiveness of the proposed method.

Key-dependent message (KDM) security is an important security issue that has attracted much research in recent years. In this paper, we present a new construction of the symmetric encryption scheme in the the ideal cipher model (ICM); we prove that our scheme is KDM secure against active attacks with respect to arbitrary polynomialtime challenge functions. Our main idea is to introduce a universal hash function (UHF) h as a random value for each encryption, and then use s = h(sk) as the key of the ideal cipher F, where sk is the private key of our symmetric encryption scheme. Although many other schemes that are secure against KDM attacks have already been proposed, in both the ideal standard models, the much more significance of our paper is the simplicity in which we implement KDM security against active attacks.

Authentication per frame and symmetric key based encryption is an implicit necessity for security in Wireless Local Area Networks (LANs). We propose a novel symmetric key based secure WLAN communication scheme. The scheme provides authentication per frame, generates new secret key for encryption of each frame and involves less message exchanges for maintaining the freshness of key and initial vector (IV). It enhances wireless security by utilizing key hiding concept for sharing the symmetric secret key and IV. The shared secret encryption key and IV are protected using counters and then mixed with each other before sending. We prove security of the scheme in Canetti–Krawczyk model.

This paper proposes to cryptanalyze a partial image encryption scheme. Security weaknesses were found in the cryptosystem consisting in the generation of the keystream. We then propose a modified version of the partial encryption scheme to enhance its security together with keeping the benefit of encrypting a reduced amount of data. Our contributions can be resumed in two points : we will first show the insecurity of the cryptosystem under study then we will propose a remedy to resist the described attacks.

Network coding has been shown to offer an intrinsic security advantage in terms of node-based wiretapping attack. Previous literature explored the security advantage by defining and investigating the security level at an arbitrary intermediate node. As pointed out in other studies and observed by us, in order to achieve the security level at all intermediate nodes, it is necessary to have an admissible link encryption scheme to prevent all links from eavesdropping. “Admissibility” here promises that an adversary cannot obtain more meaningful (decoded or decodable) information about the original message than that disclosed at the node he controls. In this article, we study a similar problem but focus on link encryption. We propose an admissible link encryption scheme LNCLE; in conjunction with LNCLE, linear network coding achieves its security level at all intermediate nodes. In comparison with a trivial link encryption scheme (TLE) which is based on classical link encryption, LNCLE is more efficient in the sense that both key size and computation cost are greatly reduced.

For an encryption scheme to be applied in practical applications, it should withstand various leakage attacks. In this paper, we present a new leakage-resilient public key encryption scheme whose security is based on the classical DDH (decisional Diffie-Hellman) assumption. In the computational cost, our proposed scheme is more efficient than the original Cramer-Shoup leakage-resilient public key encryption scheme. At the same time, our new scheme also enjoys a shorter (public and secret) key length, and a higher relative key leakage ratio. We formally prove our new proposal is semantically secure against adaptive posteriori chosen ciphertext key-leakage attacks assuming the hardness of the DDH problem without random models.

Content protection that allows only legitimate users to use specified content is essential in order to secure business in the consumer market. However, service providers and users suffer from low responsiveness when content is encrypted with traditional cryptographic tools that require strong decryption algorithms on mobile devices. In this paper, we introduce a generic partial encryption scheme for low-power mobile devices. Our primary goal is to design a generic architecture for partial encryption of downloadable and real-time streaming contents, and also to facilitate a trade-off between minimizing the encryption/decryption overhead and providing sufficient DRM security for the service provider. We also evaluate the efficacy of our proposed scheme by applying it to real-world multimedia contents. The results of our experiments indicate that encrypting only a small portion (about 2.5 %) of video content can effectively impose DRM restriction on the content. This significantly reduces the decryption overhead on low-power mobile devices. In the smart phone environment, it is shown that the time overhead during the decryption is less that 5 % of on-the-fly decoding time and the power overhead is reduced by up to 94.5 %, compared to the traditional full encryption scheme.

The Selective Encryption method encrypts the important and requisite parts of data. Since the method does not encrypt the whole of data, the amount of computation is small,which makes it faster and the resources can be used efficiently. The existing selective algorithms have vulnerabilities to the plain text attack and the image restoration attack using the motion vector. They are also vulnerable to the attack in storing and transmitting of the random table data using in encrypt and scramble. In this paper, we propose the selective encryption algorithm of motion vector based on S-Box to remove the vulnerabilities of the existing selective algorithms. The motion vectors generated by the end of motion estimation function of video encoding/decoding xored with S-Box table, are replaced to certain location by using mapping table. The S-Box and mapping table are generated by the secret key through the Rivest Cipher 4 (RC4) encryption algorithm. The proposed algorithm enhances the resistance against attacks through the reinforcement of video security, and thus, reduces the vulnerabilities of the existing algorithms such as I-Frame selective encryption and MVEA. Even though the level of security of the proposed algorithm is higher than the bit scrambling algorithms, it has much better security and higher processing rate than others selective algorithms.

Low powered devices, such as smart phones, tablets and sensors, present a particular challenge for advanced encryption systems. In this paper, we present a new quasigroup block encryption system that has low memory and computational requirements and hence suitable for low powered devices. We compare its performance against Advanced Encryption Standard-256 (AES-256) bit algorithm using the NIST statistical test suite (NIST-STS). Since it is well known that a good encryption algorithm must destroy any statistical properties of the input sequence and produce output close to a true random sequence, the NIST-STS suite results provide us a good test bench. In almost all tests from the suite, the proposed algorithm performs better than AES-256.

The efficient transmission of images at low bit rate with high security has gained momentum due to recent explosion in networking and multimedia applications. Mixing several existing standard encryption techniques with image encoding tend to change the bit rate greatly. In this paper, FPGA implementation of a novel image encryption algorithm, based on block and symbol scrambling is proposed as a part of JPEG image encoding scheme to meet four major requirements: (1) to provide temporal security, (2) to preserve the overall bit rate with negligible overhead, (3) remain complaint with the JPEG file format, (4) fast and less complex implementation for real time applications. Implementation of the algorithm in an efficient manner with low complexity is a requirement for real time tactical security applications. The algorithm is implemented on STRATIX II and IV FPGAs using only 1 % extra hardware for encryption than that of the basic JPEG. Further, the JPEG implementation without encryption is competitive with other implementations available in literature. The implemented encryption module can be used in the image transmission system for secure image coding and tactical communications.

Real-time video streams require an efficient encryption method to ensure their confidentiality. One of the major challenges in designing a video encryption algorithm is to encrypt the vast amount of video data in real-time to satisfy the stringent time requirements. Video encryption algorithms can be classified according to their association with video compression into joint compression and encryption algorithms and compression-independent encryption algorithms. The latter have a clear advantage over the former regarding the incorporation into existing multimedia systems due to their independence of the video compression. In this paper we present the compression-independent video encryption algorithm Puzzle, which was inspired by the children game jigsaw puzzle. It comprises two simple encryption operations with low computational complexity: puzzling and obscuring. The scheme thereby dramatically reduces the encryption overhead compared to conventional encryption algorithms, such as AES, especially for high resolution video. Further outstanding features of Puzzle are a good trade-off between security demands and encryption efficiency, no impairment on video compression efficiency, and an easy integration into existing multimedia systems. This makes Puzzle particularly well-suited for these security-sensitive multimedia applications, such as videoconferencing, where maximal security and minimal encryption overhead are desired simultaneously.

In today's world, the security of information is associated with valid and reliable encryption algorithms that we have used in our systems. Today, the latest methods for data encryption are based on DNA computing. In this paper, we consider a reliable data encryption algorithm (OTP) which is theoretically unbreakable, but it experiences some disadvantages in its algorithm. These drawbacks have prevented the common use of its scheme in modern cryptosystems. In this research, we include a logistic chaotic map as an input of OTP algorithm. So, the obtained result of `Matlab Simulation' could prove the efficiency of proposed algorithm in image encryption. In addition to the cryptography of text files, we can propose an interesting encryption algorithm based on a chaotic selection between original message DNA strands and OTP DNA strands. Finally, the empirical results of our proposed algorithm will be compared with AES Open SSl algorithm.

An encryption scheme is non-malleable if giving an encryption of a message to an adversary does not increase its chances of producing an encryption of a related message (under a given public key). Fischlin introduced a stronger notion, known as complete non-malleability, which requires attackers to have negligible advantage, even if they are allowed to transform the public key under which the related message is encrypted. Ventre and Visconti later proposed a comparison-based definition of this security notion, which is more in line with the well-studied definitions proposed by Bellare et al. The authors also provide additional feasibility results by proposing two constructions of completely non-malleable schemes, one in the common reference string model using non-interactive zero-knowledge proofs, and another using interactive encryption schemes. Therefore, the only previously known completely non-malleable (and non-interactive) scheme in the standard model, is quite inefficient as it relies on generic NIZK approach. They left the existence of efficient schemes in the common reference string model as an open problem. Recently, two efficient public-key encryption schemes have been proposed by Libert and Yung, and Barbosa and Farshim, both of them are based on pairing identity-based encryption. At ACISP 2011, Sepahi et al. proposed a method to achieve completely non-malleable encryption in the public-key setting using lattices but there is no security proof for the proposed scheme. In this paper we review the mentioned scheme and provide its security proof in the standard model. Our study shows that Sepahi's scheme will remain secure even for post-quantum world since there are currently no known quantum algorithms for solving lattice problems that perform significantly better than the best known classical (i.e., non-quantum) algorithms.

Image encryption is a challenging task due to the significant level of sophistication achieved by forgerers and other cybercriminals. Advanced encryption methods for secure transmission, storage, and retrieval of digital images are increasingly needed for a number of military, medical, homeland security, and other applications. In this paper, we introduce a new digital image encryption algorithm. The new algorithm employs multiple chaotic systems and cryptographic primitive operations within the encryption process, which are efficiently implemented on modern processors, and adopts round keys for encryption using a chaotic map. Experiments conducted show that the proposed algorithm possesses robust security features such as fairly uniform distribution, high sensitivity to both keys and plainimages, almost ideal entropy, and the ability to highly de-correlate adjacent pixels in the cipherimages. Furthermore, it has a large key space, which greatly increases its security for image encryption applications.

A VoIP encryption module was designed to prevent eavesdropping on Internet telephones communications and involved encoding/decoding the output data at the transmitter and receiver of the Internet telephone. To reduce the voice delay, a 128 bit AES was used and an RSA algorithm for an asymmetric encoding system was used during the key exchange, which is the first process of the encryption system operation. In order to test the speech quality in the encryption system, a Mean Opinion Score (MOS) value and R-value (E Model) Score were measured and resulted in values of 4.18~4.20 (Good) and 91.77~92.92 (Good), respectively.

Encryption is one of the fundamental technologies that is used in the security of multimedia data. Unlike ordinary computer applications, multimedia applications generate large amount of data that has to be processed in real time. This work investigates the problem of efficient multimedia data encryption. A scheme known as the Randomized Huffman Table scheme was recently proposed to achieve encryption along with compression. Though this scheme has several advantages it cannot overcome the chosen plaintext attack. An enhancement of this Huffman scheme is proposed in this work which essentially overcomes the attack and improves the security. The proposed encryption approach consists of two modules. The first module is the Randomized Huffman Table module, the output of which is fed to the second XOR module to enhance the performance. Security analysis shows that the proposed scheme can withstand the chosen plaintext attack. The efficiency and security of the proposed scheme makes it an ideal choice for real time secure multimedia applications.

This paper presents a generic conversion from weak asymmetric and symmetric encryption schemes to an asymmetric encryption scheme that is chosen-ciphertext secure in the random oracle model. Our conversion is the first generic transformation from an arbitrary one-way asymmetric encryption scheme to a chosen-ciphertext secure asymmetric encryption scheme in the random oracle model.

This paper shows several security weaknesses of a threshold authenticated encryption scheme. A new threshold authenticated encryption scheme using labor-division signature is proposed without redundancy added to message blocks. On the assumptions of EDDH problems, the proposed scheme is secure against chosen-ciphertext attacks and existentially unforgeable against the chosen-message attacks in the random oracle model.

Nowadays, indistinguishability against adaptive chosen-ciphertext attacks (IND-CCA2) has been widely accepted as a proper security criterion for encryption schemes. In this paper, an efficient conversion is proposed to satisfy the IND-CCA2 security. It uses the random oracle methodology and the idea of hybrid encryption, and can enhance any Diffie-Hellman based encryption scheme, which is only one-way under plaintext-checking attack. Compared with other existing conversions, this conversion has the advantages of short ciphertext and low computation overhead, especially when it is applied to the multi-recipient setting.

International audience; Chosen-ciphertext security is by now a standard security property for asymmetric encryption. Many generic constructions for building secure cryptosystems from primitives with lower level of security have been proposed. Providing security proofs has also become standard practice. There is, however, a lack of automated verification procedures that analyze such cryp-tosystems and provide security proofs. This paper presents an automated procedure for analyzing generic asymmetric encryption schemes in the random oracle model. It has been applied to several examples of encryption schemes among which the construction of Bellare-Rogaway 1993, of Pointcheval at PKC'2000 and REACT.

We address the cryptographic topic of proxy re-encryption (PRE), which is a special public-key cryptosystem. A PRE scheme allows a special entity, known as the proxy, to transform a message encrypted with the public key of a delegator (say Alice), into a new ciphertext that is protected under the public key of a delegatee (say Bob), and thus the same message can then be recovered with Bob's private key. In this paper, in the identity-based setting, we first investigate the relationship between so called mediated encryption and unidirectional PRE. We provide a general framework which converts any secure identity-based unidirectional PRE scheme into a secure identity-based mediated encryption scheme, and vice versa. Concerning the security for unidirectional PRE schemes, Ateniese et al. previously suggested an important property known as the master secret security, which requires that the coalition of the proxy and Bob cannot expose Alice's private key. In this paper, we extend the notion to the identity-based setting, and present an identity-based unidirectional PRE scheme, which not only is provably secure against the chosen ciphertext attack in the standard model but also achieves the master secret security at the same time.