Elliptic Curve Cryptography Services for Mobile Operating Systems

Mobile devices as smartphones, tablets and laptops, are nowadays considered indispensable objects by most people in developed countries. A s personal and work assistant s , some of th e s e devices store , process and transmit sensitive and private data. Naturally , the number of mobile applications with integrated cryptographic mechanisms or offering security services has been significantly increasing in the last few years. Unfortunately, not all of those applications are secure by design, while other may not implement the cryptographic primitives correctly. Even the ones that implement them correctly may suffer from longevity problems, since cryptographic primitives that are considered secure nowadays may become obsolete in the next few years. Rivest, Shamir and Adleman (RSA) is an example of an widely used cryptosystem that may become depleted shorty . While the security issues in the mobile computing environment may be of median severity for casual users, they may be critical for several professional classes, namely lawyers, journalists and law enforcement agents. As such, it is important to approach these problems in a structured manner. This master’s program is focused on the engineering and implementation of a mobile application offering a series of security services. The application was engineered to be secure by design for the Windows Phone 8.1 Operating System (OS) which, at the time of writing this dissertation, was the platform with the most discreet offer in terms of applications of this type. The application provides services such as secure exchange of a cryptographic secret, encryption and digital signature of messages and files, management of contacts and encryption keys and secure password generation and storage. Part of the cryptographic primitives used in this work are from the Elliptic Curve Cryptography (ECC) theory, for which the discrete logarithm problem is believed to be harder and key handling is easier. The library defining a series of curves and containing the procedures and operations supporting the ECC primitives was implemented from scratch, since there was none available, comprising one of the contributions of this work. The work evolved from the analysis of the state-of-the-art to the requirements analysis and software engineering phase, thoroughly described herein, ending up with the development of a prototype. The engineering of the application included the definition of a trust model for the exchange of public keys and the modeling of the supporting database. The most visible outcomes of this master’s program are the fully working prototype of a mobile application offering the aforementioned security services, the implementation of an ECC library for the .NET framework, and this dissertation. The source code for the ECC library was made available online on GitHub with the name ECCryptoLib [Ana15]. Its development and improvement was mostly dominated by unit testing. The library and the mobile application were developed in C?. The level of security offered by the application is guaranteed via the orchestration and combination of state-of-the-art symmetric key cryptography algorithms, as the Advanced Encryption Standard (AES) and Secure Hash Algorithm 256 (SHA256) with the ECC primitives. The generation of passwords is done by using several sensors and inputs as entropy sources, which are fed to a cryptographically secure hash function. The passwords are stored in an encrypted database, whose encryption key changes every time it is opened, obtained using a Password-Based Key Derivation Function 2 (PBKDF2) from a master password. The trust model for the public keys designed in the scope of this work is inspired in Pretty Good Privacy (PGP), but granularity of the trust levels is larger.Dispositivos móveis como computadores portáteis, smartphones ou tablets, são, nos dias de hoje, considerados objectos indispensáveis pela grande maioria das pessoas residentes em países desenvolvidos. Por serem utilizados como assistentes pessoais ou de trabalho, alguns destes dispositivos guardam, processam e transmitem dados sensíveis ou privados. Naturalmente, o número de aplicações móveis com mecanismos criptográficos integrados ou que oferecem serviços de segurança, tem vindo a aumentar de forma significativa nos últimos anos. Infelizmente, nem todas as aplicações são seguras por construção, e outras podem não implementar as primitivas criptográficas corretamente. Mesmo aquelas que as implementam corretamente podem sofrer de problemas de longevidade, já que primitivas criptográficas que são hoje em dia consideradas seguras podem tornar-se obsoletas nos próximos anos. O Rivest, Shamir and Adleman (RSA) constitui um exemplo de um sistema criptográfico muito popular que se pode tornar obsoleto a curto prazo. Enquanto que os problemas de segurança em ambientes de computação móvel podem ser de média severidade para utilizadores casuais, estes são normalmente críticos para várias classes profissionais, nomeadamente advogados, jornalistas e oficiais da justiça. É, por isso, importante, abordar estes problemas de uma forma estruturada. Este programa de mestrado foca-se na engenharia e implementação de uma aplicação móvel que oferece uma série de serviços de segurança. A aplicação foi desenhada para ser segura por construção para o sistema operativo Windows Phone 8.1 que, altura em que esta dissertação foi escrita, era a plataforma com a oferta mais discreta em termos de aplicações deste tipo. A aplicação fornece funcionalidades como trocar um segredo criptográfico entre duas entidades de forma segura, cifra, decifra e assinatura digital de mensagens e ficheiros, gestão de contactos e chaves de cifra, e geração e armazenamento seguro de palavras-passe. Parte das primitivas criptográficas utilizadas neste trabalho fazem parte da teoria da criptografia em curvas elípticas, para a qual se acredita que o problema do logaritmo discreto é de mais difícil resolução e para o qual a manipulação de chaves é mais simples. A biblioteca que define uma série de curvas, e contendo os procedimentos e operações que suportam as primitivas criptográficas, foi totalmente implementada no âmbito deste trabalho, dado ainda não existir nenhuma disponível no seu início, compreendendo assim uma das suas contribuições. O trabalho evoluiu da análise do estado da arte para o levantamento dos requisitos e para a fase de engenharia de software, aqui descrita detalhadamente, culminando no desenvolvimento de um protótipo. A engenharia da aplicação incluiu a definição de um sistema de confiança para troca de chaves públicas e também modelação da base de dados de suporte. Os resultados mais visíveis deste programa de mestrado são o protótipo da aplicação móvel, completamente funcional e disponibilizando as funcionalidades de segurança acima mencionadas, a implementação de uma biblioteca Elliptic Curve Cryptography (ECC) para framework .NET, e esta dissertação. O código fonte com a implementação da biblioteca foi publicada online. O seu desenvolvimento e melhoramento foi sobretudo dominado por testes unitários. A biblioteca e a aplicação móvel foram desenvolvidas em C?. O nível de segurança oferecido pela aplicação é garantido através da orquestração e combinação de algoritmos da criptografia de chave simétrica atuais, como o Advanced Encryption Standard (AES) e o Secure Hash Algorithm 256 (SHA256), com as primitivas ECC. A geração de palavras-passe é feita recorrendo utilizando vários sensores e dispoitivos de entrada como fontes de entropia, que posteriormente são alimentadas a uma função de hash criptográfica. As palavras-passe são guardadas numa base de dados cifrada, cuja chave de cifra muda sempre que a base de dados é aberta, sendo obtida através da aplicação de um Password-Based Key Derivation Function 2 (PBKDF2) a uma palavrapasse mestre. O modelo de confiança para chaves públicas desenhado no âmbito deste trabalho é inspirado no Pretty Good Privacy (PGP), mas a granularidade dos níveis de confiança é superior

Ubic: Bridging the gap between digital cryptography and the physical world

Advances in computing technology increasingly blur the boundary between the digital domain and the physical world. Although the research community has developed a large number of cryptographic primitives and has demonstrated their usability in all-digital communication, many of them have not yet made their way into the real world due to usability aspects. We aim to make another step towards a tighter integration of digital cryptography into real world interactions. We describe Ubic, a framework that allows users to bridge the gap between digital cryptography and the physical world. Ubic relies on head-mounted displays, like Google Glass, resource-friendly computer vision techniques as well as mathematically sound cryptographic primitives to provide users with better security and privacy guarantees. The framework covers key cryptographic primitives, such as secure identification, document verification using a novel secure physical document format, as well as content hiding. To make a contribution of practical value, we focused on making Ubic as simple, easily deployable, and user friendly as possible.Comment: In ESORICS 2014, volume 8712 of Lecture Notes in Computer Science, pp. 56-75, Wroclaw, Poland, September 7-11, 2014. Springer, Berlin, German

Bitcoin Wallet for Android with TREZOR Hardware Wallet Support

Tato práce se zabývá návrhem Bitcoinové peněženky pro OS Android, která využívá zařízení TREZOR jako úložiště privátních klíčů. Navržená aplikace umožňuje zobrazit seznam transakcí, vytvořit novou transakci, podepsat ji pomocí zařízení a odeslat do sítě. Vedlejším přínosem této práce je navržení Android knihovny pro usnadnění komunikace se zařízením TREZOR.The goal of this thesis is to design a Bitcoin wallet for the Android OS, using the TREZOR device as a secure private key storage. The implemented application allows to see transactions history, to compose a new transaction, sign it and broadcast it to the network. The secondary contribution of this thesis is designing an Android library simplifying the communication with the TREZOR device

Spamming the Internet of Things: A Possibility and its probable Solution

AbstractThe Internet of Things (IoT) enabled users to bring physical objects into the sphere of cyber world. This was made possible by different tagging technologies like NFC, RFID and 2D barcode which allowed physical objects to be identified and referred over the Internet. Due to less complexity and low development and deployment cost of 2D barcodes, they have become modus operandi for building an IoT system. This paper explores the possibility of spamming the Internet of Things. It tries to establish that web spammers can use 2D barcodes to flood the physical side of the IoT, trick users to see or reach unsolicited and unrelated content over the Internet and possibly destroy the legitimacy of correct content. Preliminary results from an experiment establishing the possibility of the problem are outlined. This paper also proposes the use of digital signatures (ECDSA) to address the problem of spamming the IoT. A prototype implementation of the solution and its experimental results are given in this paper

Design and Implementation of a Secure Wireless Mote-Based Medical Sensor Network

A medical sensor network can wirelessly monitor vital signs of humans, making it useful for long-term health care without sacrificing patient comfort and mobility. For such a network to be viable, its design must protect data privacy and authenticity given that medical data are highly sensitive. We identify the unique security challenges of such a sensor network and propose a set of resource-efficient mechanisms to address these challenges. Our solution includes (1) a novel two-tier scheme for verifying the authenticity of patient data, (2) a secure key agreement protocol to set up shared keys between sensor nodes and base stations, and (3) symmetric encryption/decryption for protecting data confidentiality and integrity. We have implemented the proposed mechanisms on a wireless mote platform, and our results confirm their feasibility

Secure Lifecycle Management for Internet of Things Devices

In recent years, IoT devices have been adopted for various uses cases including for home applications such as smart lighting and heating and cooling systems. The IoT devices are simple and constrained devices. Usually, these simple devices are paired with and managed by controller devices such as smartphones over home wireless network. The pairing protocol along with the command and control protocols between the IoT device and the smartphone are usually proprietary. Therefore, users are required to install a dedicated application to access and control each brand and type of device. LwM2M has been designed as an open standard to increase interoperability between the simple devices from different ecosystems. It can be used to secure the connection between the simple device and the controller. The LwM2M protocol uses pre-shared keys, raw public keys, and X.509 certificates for authentication. However, these authentication methods have some deployment and scalability problems, and out-of-band authentication has been suggested as an alternative. This thesis project aims to adapt the LwM2M protocol for secure device pairing and lifecycle management for Internet of Things device in such a way that it can be used with out-of-band authentication. A proof-of-concept prototype has been implemented with Raspberry Pi 3 B+ as the simple device and an Android smartphone as the controller

Secure Device Bootstrapping with the Nimble Out of Band Authentication Protocol

The smart personal and business appliances which form the Internet of Things are expected to become ubiquitous and to make our daily life more convenient. Most of these devices are connected though wireless networks to cloud-based online services. However, such devices may be vulnerable to various attacks which could compromise the users’ security and privacy and even cause physical harm. Therefore, securing the network connection for the devices is of utmost importance. In order to secure the network connections, the devices need to be configured with the necessary keys and other connection parameters. There is not yet any widely adopted generic solution for this secure bootstrapping. One proposed solution is out-of-band (OOB) authentication with a protocol called EAP-NOOB, which is a new method for the EAP and IEEE 802.1X authentication framework. The goal of this thesis is to build a prototype of the EAP-NOOB protocol and deploy the prototype to test it with the real-world scenarios. The protocol requires no a-priori information either about the device or the user is necessary for the bootstrapping. Instead, the user’s ownership of the device is established during the bootstrapping process. The protocol was implemented both by adding support for the new EAP method into existing open-source software, the commonly used WPA_Supplicant and Hostapd packages. We also implemented a web interface for the back-end authentication server, which works in tandem with the AAA server, and out-of-band channels based on dynamic QR codes and NFC tags. We used the prototype to test and demonstrate the EAP-NOOB protocol, including its usability and authentication latency. The bootstrapping procedure can be completed in less than a minute in most cases. The main results of the project are the EAP-NOOB implementation and various improvements and clarifications to the protocol specification. These results are an essential part of the protocol standardization process at IETF