875 research outputs found

    Perfect security in cryptography

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    U ovom radu je detaljno objašnjena savršena sigurnost kriptosustava. Dan je primjer kriptosustava koji nije savršeno siguran te je definiran i prikazan jedan savršeno siguran kriptosustav, Vernamova jednokratna bilježnica. Iskazan je i dokazan Shannonov teorem o nužnim i dovoljnim uvjetima savršene sigurnosti kriptosustava. Definirani su pojmovi entropije, uvjetne entropije i višeznačnosti ključa uz popratne primjere za razumijevanje. Na kraju je pojam entropije povezan sa savršenom sigurnosti.This thesis explains perfect secrecy of cryptosystems in detail. It gives an example of a cryptosystem that is not perfectly secret, and it defines and shows a cryptosystem that is perfectly secret - Vernam cipher known as one-time pad. Shannon’s theorem about necessary and sufficient conditions for perfectly secret cryptosystems is stated and proven in the thesis. Terms of entropy, conditional entropy and key equivocation are introduced with supporting examples for better understanding. In the end, the thesis explains the connection of entropy and perfect secrecy

    Perfect security in cryptography

    No full text
    U ovom radu je detaljno objašnjena savršena sigurnost kriptosustava. Dan je primjer kriptosustava koji nije savršeno siguran te je definiran i prikazan jedan savršeno siguran kriptosustav, Vernamova jednokratna bilježnica. Iskazan je i dokazan Shannonov teorem o nužnim i dovoljnim uvjetima savršene sigurnosti kriptosustava. Definirani su pojmovi entropije, uvjetne entropije i višeznačnosti ključa uz popratne primjere za razumijevanje. Na kraju je pojam entropije povezan sa savršenom sigurnosti.This thesis explains perfect secrecy of cryptosystems in detail. It gives an example of a cryptosystem that is not perfectly secret, and it defines and shows a cryptosystem that is perfectly secret - Vernam cipher known as one-time pad. Shannon’s theorem about necessary and sufficient conditions for perfectly secret cryptosystems is stated and proven in the thesis. Terms of entropy, conditional entropy and key equivocation are introduced with supporting examples for better understanding. In the end, the thesis explains the connection of entropy and perfect secrecy

    PENERAPAN ALGORITMA ADVANCED ENCRYPTION STANDARD (AES)-128 BIT PADA KEAMANAN DATABASE APLIKASI KEPELANGGANAN (STUDI KASUS: PERUMDA AIR MINUM TIRTA KHATULISTIWA)

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    Data salah satu aspek penting menjadi aset perusahaan sehingga perlu dilakukan teknik keamanan untuk mencegah adanya pemanipulasian serta penyebarluasan informasi yang bersifat rahasia. Dalam hal ini dilakukan pada data kepelangganan di PERUMDA Air Minum Tirta Khatulistiwa yang berwewenang melakukan pelayanan air minum yang dimanfaatkan oleh pelanggan. Saat ini berbagai sistem pengelolaan data telah dilakukan secara terkomputerisasi. Namun, pada media penyimpanan data masih ditampilkan dalam bentuk informasi yang dapat diketahui langsung oleh penggunanya. Hal ini dapat menjadi celah bagi orang yang tidak berhak untuk melakukan penyadapan data demi kepentingan tertentu yang dapat menyebabkan kerugian. Untuk mengantisipasi masalah tersebut, dilakukan penelitian dengan membuat sebuah aplikasi kepelangganan berbasis website yang dapat merahasiakan data-data kepelangganan dengan menerapkan algoritma kriptografi Advanced Encryption Standard (AES)-128 Bit sebagai sistem perlindungan data. Kriptografi AES merupakan salah satu cipherblok tetap dan kunci simetris. Data yang disimpan merupakan hasil dari proses enkripsi sedangkan data yang ditampilkan merupakan hasil dari proses dekripsi. Berdasarkan hasil pengujian yang dilakukan, seluruh data dienkripsi dengan baik dan memiliki tingkat linieritas jumlah karakter hasil enkripsi terhadap karakter asli dengan persentase 70,3%, artinya data yang ditampilkan telah terenkripsi sesuai dengan algoritma yang diterapkan

    SAFE-NET: Secure and Fast Encryption using Network of Pseudo-Random Number Generators

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    We propose a general framework to design a general class of random number generators suit- able for both computer simulation and computer security applications. It can include newly pro- posed generators SAFE (Secure And Fast Encryption) and ChaCha, a variant of Salsa, one of the four finalists of the eSTREAM ciphers. Two requirements for ciphers to be considered se- cure is that they must be unpredictable with a nice distributional property. Proposed SAFE-NET is a network of n nodes with external pseudo-random number generators as inputs nodes, several inner layers of nodes with a sequence of random variates through ARX (Addition, Rotation, XOR) transformations to diffuse the components of the initial state vector. After several rounds of transformations (with complex inner connections) are done, the output layer with n nodes are outputted via additional transformations. By utilizing random number generators with desirable empirical properties, SAFE-NET injects randomness into the keystream generation process and constantly updates the cipher’s state with external pseudo-random numbers during each iteration. Through the integration of shuffle tables and advanced output functions, extra layers of security are provided, making it harder for attackers to exploit weaknesses in the cipher. Empirical results demonstrate that SAFE-NET requires fewer operations than ChaCha while still producing a sequence of uniformly distributed random numbers

    Proof of the possibility for a public audit of a secret internet voting system

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    The aim of this study is to prove the possibility of building a system of secret Internet voting, in which a full-fledged audit is available to all voters and their proxies. A full-fledged audit should be understood as such an audit, in which everything that may be in doubt is checked. The open block of servers was created using Raspberry Pi 3 Model B type minicomputers, which are widely known and well-established. On the basis of an open block of servers, a full-scale model of the system for conducting experimental voting was created and a detailed methodology for a full-fledged audit was developed. This methodology provides for two stages of the audit. In the first stage, voters or their proxies must be present near the server unit. In the second stage, they continue the audit remotely through a dedicated server without losing information about the security of their data. For practical acquaintance with this research, the possibility of experimental voting is given. The experiment can be conducted by anyone at any time through a link on the Internet. Thus, it is shown that not only with traditional secret voting technologies, a full-fledged audit is possible, thanks to which voters have no doubts about maintaining the secrecy of their votes and the honesty of the results. To conduct a full-fledged audit according to the described methodology, it is not require to involve highly qualified specialists, but school education, which is mandatory in many countries, is quite enough. The importance of the results is that the lack of a full-fledged audit of Internet voting systems is the main factor hindering the development of e-democracy. The lack of public auditing of Internet voting systems causes distrust in the possibility of using the Internet to conduct fair election

    Pattern Devoid Cryptography

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    Pattern-loaded ciphers are at risk of being compromised by exploiting deeper patterns discovered first by the attacker. This reality offers a built-in advantage to prime cryptanalysis institutions. On the flip side, the risk of hidden math and faster computing undermines confidence in the prevailing cipher products. To avoid this risk one would resort to building security on the premise of lavish quantities of randomness. Gilbert S. Vernam did it in 1917. Using modern technology, the same idea of randomness-based security can be implemented without the inconvenience associated with the old Vernam cipher. These are Trans Vernam Ciphers that project security through a pattern-devoid cipher. Having no pattern to lean on, there is no pattern to crack. The attacker faces (i) a properly randomized shared cryptographic key combined with (ii) unilateral randomness, originated ad-hoc by the transmitter without pre-coordination with the recipient. The unlimited unilateral randomness together with the shared key randomness is set to project as much security as desired up to and including Vernam levels. Assorted Trans Vernam ciphers (TVC) are categorized and reviewed, presenting a cogent message in favor of a cryptographic pathway where transmitted secrets are credibly secured against attackers with faster computers and better mathematicians

    Deploying hybrid quantum-secured infrastructure for applications: When quantum and post-quantum can work together

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    Most currently used cryptographic tools for protecting data are based on certain computational assumptions, which makes them vulnerable with respect to technological and algorithmic developments, such as quantum computing. One existing option to counter this potential threat is quantum key distribution, whose security is based on the laws of quantum physics. Quantum key distribution is secure against unforeseen technological developments. A second approach is post-quantum cryptography, which is a set of cryptographic primitives that are believed to be secure even against attacks with both classical and quantum computing technologies. From this perspective, this study reviews recent progress in the deployment of the quantum-secured infrastructure based on quantum key distribution, post-quantum cryptography, and their combinations. Various directions in the further development of the full-stack quantum-secured infrastructure are also indicated. Distributed applications, such as blockchains and distributed ledgers, are also discussed.Comment: 11 pages, 0 figures, 1 table; Perspective pape

    Fundamental Limitations within the Selected Cryptographic Scenarios and Supra-Quantum Theories

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    The following submission constitutes a guide and an introduction to a collection of articles submitted as a Ph.D. dissertation at the University of Gda\'nsk. In the dissertation, we study the fundamental limitations within the selected quantum and supra-quantum cryptographic scenarios in the form of upper bounds on the achievable key rates. We investigate various security paradigms, bipartite and multipartite settings, as well as single-shot and asymptotic regimes. Our studies, however, extend beyond the derivations of the upper bounds on the secret key rates in the mentioned scenarios. In particular, we propose a novel type of rerouting attack on the quantum Internet for which we find a countermeasure and benchmark its efficiency. Furthermore, we propose several upper bounds on the performance of quantum (key) repeaters settings. We derive a lower bound on the secret key agreement capacity of a quantum network, which we tighten in an important case of a bidirectional quantum network. The squashed nonlocality derived here as an upper bound on the secret key rate is a novel non-faithful measure of nonlocality. Furthermore, the notion of the non-signaling complete extension arising from the complete extension postulate as a counterpart of purification of a quantum state allows us to study analogies between non-signaling and quantum key distribution scenarios.Comment: PhD Thesis, University of Gda\'nsk, July 202

    Hiding algorithm based fused images and Caesar cipher with intelligent security enhancement

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    The process of sending confidential data through the communication media and in complete secrecy is now necessary, whether the data is related to patients, a particular military operation, or a specified office. On the other hand, with the development of various ciphering algorithms, and information hiding algorithms, there is a need to obtain ciphered and hidden data securely without the need to exchange secret keys between the two ends of the communication. In this paper, a hiding algorithm based on fused images and Caesar cipher with intelligent methods to strengthen the security of confidential information is proposed. Firstly, fused image scattering is obtained using 1’s complement and circularly shifting the bits of fused pixels by specified positions before the hiding process. Secondly, the keys for the Caesar cipher are derived from the length of secret information according to the mathematical equation. Thirdly, strengthen the security of Caesar’s cipher by taking a 1’s complement of each letter in the cipher data. The results guarantee the security of the presented algorithm
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