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Secret Sharing Authentication Key Agreement
Ryšavá, Pavla ; Dzurenda, Petr (oponent) ; Ricci, Sara (vedoucí práce)
This thesis deals with the implementation and creation of a cryptographic library and Graphical User Interface (GUI) for the newly designed "Shamir’s Secret Sharing-based Authenticated Key Agreement" (ShSSAKA) protocol. The protocol is based on the principle of AKA (Authentication and Key Agreement), Schnorr’s signature and extended with Paillier’s scheme to achieve multiple devices deploying signing and authentication. Benchmarks on a personal computer and RaspberryPi are also presented.
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Lightweight Multi-signature schemes for IoT
Jarina, Jakub ; Dzurenda, Petr (oponent) ; Ricci, Sara (vedoucí práce)
The focus of this work is to introduce the topic of multi-signatures and subsequently implement a scheme supported for Internet of Things (IoT) devices. The work analyzes known multi-signature schemes from the perspective of security, computational complexity, and memory requirements. The work includes the implementations of a Flexible Round-Optimized Schnorr Threshold signature and Threshold Signature for Privacy preserving Blockchain in the C programming language.
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Analysis and detection of PWS malware
Blažek, Jan ; Ricci, Sara (oponent) ; Dzurenda, Petr (vedoucí práce)
The aim of this bachelor’s thesis is to study the issue of malicious code and its various types, with a specific focus on the type known as Password Stealers (PWS). The thesis presents various methods of analyzing binary executable code, such as static and dynamic analysis, or sandboxing. Using these methods, eleven malware families have been analyzed. Three of them are new discoveries. The thesis also deals with the creation of detection and classification rules and their subsequent implementation in the YARA language. Several detection rules are created in the text to classify specific families of PWS types. The thesis presents the resulting data illustrating the spread of the described malware in the user base of the Avast company. Finally, a laboratory exercise focused on reverse engineering and malware analysis is presented at the end of the thesis.
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Group signature based on Secure Multi-party Computation
Klasovitý, Kristián ; Dzurenda, Petr (oponent) ; Ricci, Sara (vedoucí práce)
This thesis aims at implementing a group signature scheme that uses two-party computation to jointly compute a signing value used in the signature. In this way, the user’s secret key is hidden from the manager and it cannot be used to impersonate the user. The signature also supports revocation and opening algorithms. Moreover, a blind issuance attribute-based credential is also presented, where the credential issued by the issuer remains private to the user. Both schemes were run on different devices and the performances were benchmarked. At last, the group signature was used to implement an application allowing one to sign a document on behalf of a group. The implementation is run on multiple devices that use NFC to communicate.
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Paillier Cryptosystem Optimisations for Homomorphic Computation.
Ryšavá, P. ; Ricci, S.
Homomorphic encryptions can ensure privacy in systems operating with sensitive data. It also allows outsourcing the data processing without the need to disclose the information within. To keep good performance over the growing mass of data, the execution of homomorphic schemes has to be efficient. In this article, we focus on the optimization of the Paillier scheme. This scheme allows the addition of a constant or another ciphertext without decryption of the encrypted values. Since the exponentiation used in the encryption process is time-consuming, we have implemented noise and message pre-computation to avoid time-demanding operations. These adjustments significantly fasten the encryption process, especially using the noise pre-computation.
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An Implementation of Lattice-based Proof-of-Work on Blockchain
Krivulčík, A. ; Ricci, S.
Cryptocurrencies and blockchain are skyrocketing in recent years. They rely on Proof-of-Work (PoW) mechanisms for generating a new transaction and turn this process into ”work” (i.e., puzzles) where miners are paid for. With the advent of quantum computers, also PoW starts to migrate to post-quantum cryptographic alternatives. To the best of our knowledge, we present the first implementation of a lattice-based PoW based on the Shortest Vector Problem (SVP). By implementing in Python 3 and with the use of the NumPy library, we wrote a software that uses this concept on an artificial blockchain and demonstrates its real-world use. Even if this proposal has drawbacks on GPU optimisation and storage requirements, it shows its potential in use. The experimental results show that by balancing the size and generated range of a given matrix and vector, we can easily manipulate the time required to solve SVP challenge.
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Secure Two-Party Computation for weak Boneh-Boyen Signature
Sečkár, M. ; Ricci, S.
Secure two-party computation allows two entities to securely calculate a common result keeping their private inputs secret. By applying this to the weak Boneh-Boyen signature, a trusted third party is able to sign the user’s message (or a secret key) without knowing its content (or value). In this article, we present a C library that implements a two-party computation algorithm for generating a user’s secret key that can be used in a group signature scheme. The library provides a structured output ready to be serialized and sent over a network. We also show the computational benchmarks of the implemented algorithms. The computations on the sender’s side are relatively fast, which broadens the possibilities of deployment on constrained devices.
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Web application demonstrating lattice-based cryptography
Sečkár, Martin ; Jedlička, Petr (oponent) ; Ricci, Sara (vedoucí práce)
The aim of this thesis is to develop and implement a web application demonstrating lattice-based cryptography. The application was developed using mainly the Python programming language and Docker container platform. More specifically, the modules utilize the Bokeh library and custom JavaScript functionality expanding the Bokeh library. The modules are hosted on a Flask server where the background calculations are being computed using numPy library. The application contains three modules describing the closest vector problem, learning with errors problem and the Boyen cryptographic protocol based on the latter problem. Users are able to visualize two dimensional lattices and perform selected computations. The codebase is easily expandable and can serve as a learning platform. The thesis also includes installation and user manual.
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Web application for Cybersecurity Job Ads Analysis
Turek, Adam ; Sikora, Marek (oponent) ; Ricci, Sara (vedoucí práce)
The bachelor’s thesis aims to create an interactive global map showing a database of job advertisements in a web application and perform filtering according to various parameters, where machine learning analysis is then performed. The map also shows the number of job advertisements by country. The web application is created using the ReactJS JavaScript library associated with LeafletJS, which provides the main functionality. The machine learning and script change parts are implemented using Python’s programming language. The thesis describes the theoretical part and implementation of individual map functions and deals with the description and successful modification of scripts to perform machine learning.
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Secret Sharing Authentication Key Agreement
Ryšavá, Pavla ; Dzurenda, Petr (oponent) ; Ricci, Sara (vedoucí práce)
This thesis deals with the implementation and creation of a cryptographic library and Graphical User Interface (GUI) for the newly designed "Shamir’s Secret Sharing-based Authenticated Key Agreement" (ShSSAKA) protocol. The protocol is based on the principle of AKA (Authentication and Key Agreement), Schnorr’s signature and extended with Paillier’s scheme to achieve multiple devices deploying signing and authentication. Benchmarks on a personal computer and RaspberryPi are also presented.
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