This thesis examines the vulnerabilities due to low-level implementation deficiencies of otherwise secure communication protocols in smart-cards. Smart-cards are considered to be one of the most secure, tamper-resistant, and trusted devices for implementing confidential operations, such as authentication, key management, encryption and decryption for financial, communication, security and data management purposes. The self-containment of smart-cards makes them resistant to attacks as they do not depend on potentially vulnerable external resources. As such, smart-cards are often incorporated in formally-verified protocols that require strong security of the cryptographic computations. Such a setting consists of a smart-card which is responsible for the execution of sensitive operations, and an Application Programming Interface (API) which implements a particular protocol. For the smart-card to execute any kind of operation there exists a confidential low-level communication with the API, responsible for carrying out the protocol specifications and requests. This communication is kept secret on purpose by some vendors, under the assumption that hiding implementation details enhances the system’s security. The work presented in this thesis analyses such low-level protocol implementations in smart-cards, especially those whose implementation details are deliberately kept secret. In particular, the thesis consists of a thorough analysis of the implementation of PKCS#11 and Bitcoin smart-cards with respect to the low-level communication layer. Our hypothesis is that by focusing on reverse-engineering the low-level implementation of the communication protocols in a disciplined and generic way, one can discover new vulnerabilities and open new attack vectors that are not possible when looking at the highest levels of implementation, thereby compromising the security guarantees of the smart-cards. We present REPROVE, a system that automatically reverse-engineers the low-level communication of PKCS#11 smart-cards, deduces the card’s functionalities and translates PKCS#11 cryptographic functions into communication steps. REPROVE deals with both standard-conforming and proprietary implementations, and does not require access to the card. We use REPROVE to reverse-engineer seven commercially available smart-cards. Moreover, we conduct a security analysis of the obtained models and expose a set of vulnerabilities which would have otherwise been unknown. To the best of our knowledge, REPROVE is the first system to address proprietary implementations and the only system that maps cryptographic functions to communication steps and on-card operations. To that end, we showcase REPROVE’s usefulness to a security ecosystem by integrating it with an existing tool to extract meaningful state-machines of the card’s implementations. To conduct a security analysis of the results we obtained, we define a threat model that addresses low-level PKCS#11 implementations. Our analysis indicates a series of implementation errors that leave the cards vulnerable to attacks. To that end, we showcase how the discovered vulnerabilities can be exploited by presenting practical attacks. The results we obtained from the PKCS#11 smart-card analysis showed that proprietary implementations commonly hide erroneous behaviours. To test the assumption that the same practice is also adopted by other protocols, we further examine the low-level implementation of the only available smart-card based Bitcoin wallets, LEDGER. We extract the different protocols that the LEDGER wallets implement and conduct a through analysis. Our results indicate a set of vulnerabilities that expose the wallets as well as the processed transactions to multiple threats. To that end, we present how we successfully mounted attacks on the LEDGER wallets that lead to the loss of the wallet’s ownership and consequently loss of the funds. We address the lack of well-defined security properties that Bitcoin wallets should conform to by introducing a general threat model. We further use that threat model to propose a lightweight fix that can be adopted by other, not necessarily smart-card-based, wallets.

A SIM, Subscriber Identity Module, is the removable circuit board found in a modern cellular phone. It carries the network identity information and is a type of smart card which can also be found on payment cards (EMV), ID cards and so on. A smart card is basically a small computer, providing a safe and controlled execution environment. Historically smart card software was very hardware dependent and mostly developed by the manufacturers themselves. With the introduction of the open Java Card standard created by Sun Microsystems (Oracle) this was meant to change. However, information still remains scattered and is hard to obtain. This paper is meant to serve both as an introduction to the field and also as a good foundation for future studies. It begins with a theoretical discussion about smart card hardware and software architectures, network standards in the context of SIM cards, typical applications, coming trends and technologies and ends off with an overview of the Java Card standard. The following section discusses the supplied example SIM card application coupled with an introduction how to use the Gemalto Developer Suite for application development and testing. The paper ends with an extensive appendix section going in depth about some of the more important subjects.

The goal of the first part of the thesis is to describe the options of wide usage of chip cards in different segments of our life. Consequently it is necessary to mention hardware and software equipment of smart card, its communication with terminal and data security. In this thesis we focus on Java Card environment in which we will try to create two applications, one for electronic purse and the second for user identification. Basically, we need to mention multiapplicational rules of sharing data and objects. At the end of the thesis we are focusing on the possibility of mutual interference between the applications and on protection against attacks. Also future applications of this technology are described.

Computer security is a growing field in the IT industry. One of the important aspects of the computer security is authentication. Using passwords (something you know) is one of the most common ways of authentications. But passwords have proven to provide weak level of security as they can be easily compromised. Some other ways of authenticating a user are using physical tokens, (something you possess) and biometrics, (something you are). Using any one of these techniques to secure a system always has its own set of threats. One way to make sure a system is secure is to use multiple factors to authenticate. One of the ways to use multiple factors is to use all the three factors of authentication, something you possess, something you are and something you know. This thesis discusses about different ways of authentication and implements a system using three factor authentication. It takes many security aspects of the system into consideration while implementing it, to make it secure.