501 research outputs found

    Structuring Statistical Tests for Validating Encryption: An Array-based Approach

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    The technological advancements made in recent years regarding the transfer of personal data have brought along an imperative need for increased security and encryption capabilities. Information sent across these electronic platforms is most often intended to be delivered to and received by specific individuals. However, the notion that these selected individuals are the only people that are able to come into contact with the information is flawed. A more realistic assumption, and the assumption that is currently demonstrated, is that the information sent can and will be intercepted. This means that successful encryption of the data is an invaluable part of the transfer process. For this reason, the study of encryption and the validation of cryptographic functions are topics that computer scientists continually work to improve. Current practice for determining the success of cryptographic functions tends to consist of various statistical tests conducted on random outputs from the algorithm. In this thesis, we propose an array-based structure to validate not only the output from an cryptographic function, but the cryptographic function itself. In using an array-based structure such as this, we do not limit ourselves to only detecting output that suggests a failure for the encryption function. With this structure we allow an opportunity to detect specific contributors to the failure within the algorithm

    Study and Implementation of Cryptographic Algorithms

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    Cryptography has a long and fascinating history. Over the centuries, an elaborate set of protocols and mechanisms has been created to deal with information security issues when the information is conveyed by physical documents. Often the objectives of information security cannot solely be achieved through mathematical algorithms and protocols alone, but require procedural techniques and abidance of laws to achieve the desired result. For example, privacy of letters is provided by sealed envelopes delivered by an accepted mail service. The physical security of the envelope is, for practical necessity, limited and so laws are enacted which make it a criminal offense to open mail for which one is not authorized. It is sometimes the case that security is achieved not through the information itself but through the physical document recording it. For example, paper currency requires special inks and material to prevent counterfeiting

    Security Evaluation of Stream Cipher Enocoro-128v2

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    Abstract in Undetermined This report presents a security evaluation of the Enocoro-128v2 stream cipher. Enocoro-128v2 was proposed in 2010 and is a member of the Enocoro family of stream ciphers. This evaluation examines several different attacks applied to the Enocoro-128v2 design. No attack better than exhaustive key search has been found

    Security of Ubiquitous Computing Systems

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    The chapters in this open access book arise out of the EU Cost Action project Cryptacus, the objective of which was to improve and adapt existent cryptanalysis methodologies and tools to the ubiquitous computing framework. The cryptanalysis implemented lies along four axes: cryptographic models, cryptanalysis of building blocks, hardware and software security engineering, and security assessment of real-world systems. The authors are top-class researchers in security and cryptography, and the contributions are of value to researchers and practitioners in these domains. This book is open access under a CC BY license

    New modification on feistel DES algorithm based on multi-level keys

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    The data encryption standard (DES) is one of the most common symmetric encryption algorithms, but it experiences many problems. For example, it uses only one function (XOR) in the encryption process, and the combination of data is finite because it occurs only twice and operates on bits. This paper presents a new modification of the DES to overcome these problems. This could be done through adding a new level of security by increasing the key space (using three keys) during the 16 rounds of the standard encryption algorithm and by replacing the predefined XOR operation with a new # operation. Our proposed algorithm uses three keys instead of one. The first key is the input key used for encrypting and decrypting operations. The second key is used for determining the number of bits, while the third key is used for determining the table numbers, which are from 0 to 255. Having evaluated the complexity of our proposed algorithm, the results show that it is the most complex compared with the well-known DES and other modified algorithms. Consequently, in our proposed algorithm, the attacker try a number of attempts 21173 at minimum to decrypt the message. This means that the proposed DES algorithm will increase the security level of the well-known DES

    Some Words on Cryptanalysis of Stream Ciphers

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    In the world of cryptography, stream ciphers are known as primitives used to ensure privacy over a communication channel. One common way to build a stream cipher is to use a keystream generator to produce a pseudo-random sequence of symbols. In such algorithms, the ciphertext is the sum of the keystream and the plaintext, resembling the one-time pad principal. Although the idea behind stream ciphers is simple, serious investigation of these primitives has started only in the late 20th century. Therefore, cryptanalysis and design of stream ciphers are important. In recent years, many designs of stream ciphers have been proposed in an effort to find a proper candidate to be chosen as a world standard for data encryption. That potential candidate should be proven good by time and by the results of cryptanalysis. Different methods of analysis, in fact, explain how a stream cipher should be constructed. Thus, techniques for cryptanalysis are also important. This thesis starts with an overview of cryptography in general, and introduces the reader to modern cryptography. Later, we focus on basic principles of design and analysis of stream ciphers. Since statistical methods are the most important cryptanalysis techniques, they will be described in detail. The practice of statistical methods reveals several bottlenecks when implementing various analysis algorithms. For example, a common property of a cipher to produce n-bit words instead of just bits makes it more natural to perform a multidimensional analysis of such a design. However, in practice, one often has to truncate the words simply because the tools needed for analysis are missing. We propose a set of algorithms and data structures for multidimensional cryptanalysis when distributions over a large probability space have to be constructed. This thesis also includes results of cryptanalysis for various cryptographic primitives, such as A5/1, Grain, SNOW 2.0, Scream, Dragon, VMPC, RC4, and RC4A. Most of these results were achieved with the help of intensive use of the proposed tools for cryptanalysis

    Modernizing Password Usage In Computing

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    A study of password usage and crypotography in computing culminates in the development of a password manager that improves users' password security. PassMan offers two-factor encrypted storage of user passwords and account information via the Yubikey, a common hardware authentication device, login auto-typing, password strength calculation, and customizable password generation. *Includes CD

    Adaptive Encryption Techniques In Wireless Communication Channels With Tradeoffs Between Communication Reliability And Security

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    Encryption is a vital process to ensure the confidentiality of the information transmitted over an insecure wireless channel. However, the nature of the wireless channel tends to deteriorate because of noise, interference and fading. Therefore, a symmetrically encrypted transmitted signal will be received with some amount of error. Consequently, due to the strict avalanche criterion (sac), this error propagates during the decryption process, resulting in half the bits (on average) after decryption to be in error. In order to alleviate this amount of error, smart coding techniques and/or new encryption algorithms that take into account the nature of wireless channels are required. The solution for this problem could involve increasing the block and key lengths which might degrade the throughput of the channel. Moreover, these solutions might significantly increase the complexity of the encryption algorithms and hence to increase the cost of its implementation and use. Two main approaches have been folloto solve this problem, the first approach is based on developing an effective coding schemes and mechanisms, in order to minimize and correct the errors introduced by the channel. The second approach is more focused on inventing and implementing new encryption algorithms that encounter less error propagation, by alleviating the sac effect. Most of the research done using these two approaches lacked the comprehensiveness in their designs. Some of these works focused on improving the error performance and/or enhancing the security on the cost of complexity and throughput. In this work, we focus on solving the problem of encryption in wireless channels in a comprehensive way that considers all of the factors in its structure (error performance, security and complexity). New encryption algorithms are proposed, which are modifications to the standardized encryption algorithms and are shown to outperform the use of these algorithms in wireless channels in terms of security and error performance with a slight addition in the complexity. We introduce new modifications that improve the error performance for a certain required security level while achieving the highest possible throughput. We show how our proposed algorithm outperforms the use of other encryption algorithms in terms of the error performance, throughput, complexity, and is secure against all known encryption attacks. In addition, we study the effect of each round and s-box in symmetric encryption algorithms on the overall probability of correct reception at the receiver after encryption and the effect on the security is analyzed as well. Moreover, we perform a complete security, complexity and energy consumption analysis to evaluate the new developed encryption techniques and procedures. We use both analytical computations and computer simulations to evaluate the effectiveness of every modification we introduce in our proposed designs
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