Biblio

Advanced Encryption Standard (AES) algorithm plays an important role in a data security application. In general S-box module in AES will give maximum confusion and diffusion measures during AES encryption and cause significant path delay overhead. In most cases, either L UTs or embedded memories are used for S- box computations which are vulnerable to attacks that pose a serious risk to real-world applications. In this paper, implementation of the composite field arithmetic-based Sub-bytes and inverse Sub-bytes operations in AES is done. The proposed work includes an efficient multiple round AES cryptosystem with higher-order transformation and composite field s-box formulation with some possible inner stage pipelining schemes which can be used for throughput rate enhancement along with path delay optimization. Finally, input biometric-driven key generation schemes are used for formulating the cipher key dynamically, which provides a higher degree of security for the computing devices.

Technology has developed to a very great extent, and the use of smart systems has introduced an increasing threat to data security and privacy. Most of the applications are built-in unsecured operating systems, and so there is a growing threat to information cloning, forging tampering counterfeiting, etc.. This will lead to an un-compensatory loss for end-users particularly in banking applications and personal data in social media. A robust and effective algorithm based on elliptic curve cryptography combined with Hill cipher has been proposed to mitigate such threats and increase information security. In this method, ciphertext and DCT coefficients of an image, embedded into the base image based on LSB watermarking. The ciphertext is generated based on the Hill Cipher algorithm. Hill Cipher can, however, be easily broken and has weak security and to add complexity, Elliptic curve cryptography (ECC), is combined with Hill cipher. Based on the ECC algorithm, the key is produced, and this key is employed to generate ciphertext through the Hill cipher algorithm. This combination of both steganography and cryptography results in increased authority and ownership of the data for sub-optimal media applications. It is hard to extract the hidden data and the image without the proper key. The performance for hiding text and image into an image data have been analyzed for sub-optimal multimedia applications.

One of the most important strength features of crypto-system's is the key space. As a result, whenever the system has more key space, it will be more resistant to attack. The weakest type of attack on the key space is Brute Force attack, which tests all the keys on the ciphertext in order to get the plaintext. But there are several strategies that can be considered by the attacker and cryptographer related to the selection of the right key with the lowest cost (time). Game theory is a mathematical theory that draws the best strategies for most problems. This research propose a new evaluation method which is employing game theory to draw best strategies for both players (cryptographer & attacker).

Quantum low probability of intercept transmits ciphertext in a way that prevents an eavesdropper possessing the decryption key from recovering the plaintext. It is capable of Gbps communication rates on optical fiber over metropolitan-area distances.

In the cloud computing environment, a growing number of users share their own data files through cloud storage. However, there will be some security and privacy problems due to the reason that the cloud is not completely trusted, so it needs to be resolved by access control. Attribute-based encryption (ABE) and searchable encryption (SE) can solve fine-grained access control. At present, researchers combine the two to propose an attribute-based searchable encryption scheme and achieved remarkable results. Nevertheless, most of existing attribute-based searchable encryption schemes cannot resist online/offline keyword guessing attack. To solve the problem, we present an attribute-based (CP-ABE) searchable encryption scheme that supports trapdoor updating (CSES-TU). In this scheme, the data owner can formulate an access strategy for the encrypted data. Only the attributes of the data user are matched with the strategy can the effective trapdoor be generated and the ciphertext be searched, and that this scheme will update trapdoors at the same time. Even if the keywords are the same, new trapdoors will be generated every time when the keyword is searched, thus minimizing the damage caused by online/offline keyword guessing attack. Finally, the performance of the scheme is analyzed, and the proof of correctness and security are given at the same time.

This paper proposes a new DNA cryptographic technique based on dynamic DNA encoding and asymmetric cryptosystem to increase the level of secrecy of data. The key idea is: to split the plaintext into fixed sized chunks, to encrypt each chunk using asymmetric cryptosystem and finally to merge the ciphertext of each chunk using dynamic DNA encoding. To generate chunks, characters of the plaintext are transformed into their equivalent ASCII values and split it into finite values. Now to encrypt each chunk, asymmetric cryptosystem is applied and the ciphertext is transformed into its equivalent binary value. Then this binary value is converted into DNA bases. Finally to merge each chunk, sufficient random strings are generated. Here to settle the required number of random strings, dynamic DNA encoding is exploited which is generated using Fibonacci series. Thus the use of finite chunks, asymmetric cryptosystem, random strings and dynamic DNA encoding increases the level of security of data. To evaluate the encryption-decryption time requirement, an empirical analysis is performed employing RSA, ElGamal and Paillier cryptosystems. The proposed technique is suitable for any use of cryptography.

Quantum cryptography and quantum search algorithm are considered as two important research topics in quantum information science. An asymmetrical quantum encryption protocol based on the properties of quantum one-way function and quantum search algorithm is proposed. Depending on the no-cloning theorem and trapdoor one-way functions of the public-key, the eavesdropper cannot extract any private-information from the public-keys and the ciphertext. Introducing key-generation randomized logarithm to improve security of our proposed protocol, i.e., one private-key corresponds to an exponential number of public-keys. Using unitary operations and the single photon measurement, secret messages can be directly sent from the sender to the receiver. The security of the proposed protocol is proved that it is information-theoretically secure. Furthermore, compared the symmetrical Quantum key distribution, the proposed protocol is not only efficient to reduce additional communication, but also easier to carry out in practice, because no entangled photons and complex operations are required.

Secure data communication is the most important and essential issue in the area of message transmission over the networks. Cryptography provides the way of making secure message for confidential message transfer. Cryptography is the process of transforming the sender's message to a secret format called cipher text that only intended receiver will get understand the meaning of the secret message. There are various cryptographic or DNA based encoding algorithms have been proposed in order to make secret message for communication. But all these proposed DNA based encryption algorithms are not secure enough to provide better security as compared with the today's security requirement. In this paper, we have proposed a technique of encryption that will enhance the message security. In this proposed algorithm, a new method of DNA based encryption with a strong key of 256 bit is used. Along with this big size key various other encoding tools are used as key in the encoding process of the message like random series of DNA bases, modified DNA bases coding. Moreover a new method of round key selection is also given in this paper to provide better security in the message. The cipher text contains the extra bit of information as similar with the DNA strands that will provide better and enhanced security against intruder's attack.