# From Research to Privacy-Preserving Industry Applications

Jesús García-Rodríguez, David Goodman, Stephan Krenn, Vasia Liagkou, Rafael Torres Moreno

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Jesús García-Rodríguez, David Goodman, Stephan Krenn, Vasia Liagkou, Rafael Torres Moreno. From Research to Privacy-Preserving Industry Applications. 17th IFIP International Summer School on Privacy and Identity Management (Privacy and Identity), Aug 2022, Virtual, Germany. pp.21-33, 10.1007/978-3-031-31971-6_3. hal-05315952

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# From Research to Privacy-Preserving Industry Applications
## Workshop Summary

Jesús García-Rodríguez¹, David Goodman², Stephan Krenn³(✉),
Vasia Liagkou⁴, and Rafael Torres Moreno¹

1 University of Murcia, Murcia, Spain

{jesus.garcia15,rtorres}@um.es

2 Trust in Digital Life, Waregem, Belgium

david@trustindigitallife.eu

3 AIT Austrian Institute of Technology, Vienna, Austria

stephan.krenn@ait.ac.at

4 Computer Technology Institute and Press “Diophantus”, Patras, Greece

liagkou@cti.gr

**Abstract.** This paper summarizes the contents and presentations held at a workshop at the IFIP Summer School on Privacy and Identity Management 2022, focusing on privacy-preserving industry applications developed within the H2020 CyberSec4Europe project. In this document, we provide a short introduction to the project, and then explain three out of the seven vertical demonstrator cases considered within Cyber-Sec4Europe, focusing on fraud detection within the banking sector, job applications, and smart cities. For each of the selected demonstrators, we motivate the need for privacy and research in the domain, and then summarize the achievements made within the project.

**Keywords:** smart cities · privacy-preserving identity management · open banking

## 1 Introduction

CyberSec4Europe¹ is a European research project, designed as one of four pilot projects for the European Cybersecurity Competence Centre (ECCC), which was established in Bucharest, as an executive agency of the European Union in 2021. As such, the ambitions of CyberSec4Europe were multifold, with one of the main goals being to ensure that the European Union has all the capabilities required to secure and maintain a healthy democratic society, living according to European constitutional values, with regard to, for example, privacy and data sharing, and being a world-leading digital economy.

Authors are listed in alphabetical order, cf. https://www.ams.org/profession/leaders/CultureStatement04.pdf.

1. https://cybersec4europe.eu/.

© IFIP International Federation for Information Processing 2023

Published by Springer Nature Switzerland AG 2023

F. Bieker et al. (Eds.): Privacy and Identity 2022, IFIP AICT 671, pp. 21–33, 2023.

https://doi.org/10.1007/978-3-031-31971-6_3
In order to identify common research directions, to scope a coherent research roadmap, and to prove the efficiency and added value of enhanced cybersecurity solutions, CyberSec4Europe selected seven vertical application domains in which multiple use cases and scenarios were researched, piloted, and evaluated:

- **Open banking** aims at identifying risks and vulnerabilities of various kinds of attacks, ranging from social engineering to malware. Furthermore, the demonstrator aims at preventing fraud and data loss in relation to monetary transactions by third parties in an open banking environment.

- **Supply chain security assurance** developed tools to make supply chain transactions traceable in all components, thereby increasing quality and integrity, and improving the detection of intentional or unintentional errors and manipulations – a key requirement for a quick response.

- **Privacy-preserving identity management** enables a distributed platform to manage identity and authenticated services. It is seeking to achieve strong, privacy-preserving authentication as well as providing consent for and controlling the data usage with privacy-preserving seamless ideals.

- **Incident reporting** was dedicated to the development of a secure and trustworthy sharing and reporting platform for security incidents, according to various procedures and methods.

- **Maritime transport** analyzed the entire maritime ecosystem, ranging from ports to ships, for cybersecurity challenges. The vertical supported stakeholders by detecting and modelling threats, developing responses, and assisting them with the related regulations and best practices.

- **Medical data exchange** was related to the sharing and protection of sensitive and/or personal medical data. The demonstrator realized a secure and trustworthy exchange of such information among actors with different objectives and requirements regarding security, data protection, and trust issues. Furthermore, the relevant legislation and policy frameworks were taken into consideration during the entire design.

- **Smart cities** connected cybersecurity challenges in an open smart city market environment based on the needs of three cities and their communities. It includes an ecosystem where new ideas, needs, best practices, lessons learned, and the information concerning are shared.

In the following sections, we will describe three demonstrator cases – open banking, privacy-preserving identity management, and smart cities – in more detail. The domains were selected in the light of the summer school's focus on privacy and identity management. For each of the verticals, we will provide a clear motivation and explain the added value of the developed solution.

## 2 Fraud Detection in Open Banking

Financial fraud is a global challenge today. As banking strategies focus on digitizing critical processes like opening a bank account or adding a recipient of funds to a bank account, it has become very easy for hackers to transact from
their living room in a short period of time and without their physical identity being revealed. Moreover, they can attack multiple banks without having to change their way of working because banks today do not readily share information about fraud cases and related data. Finally, with new applications such as Instant Payment, which offer real-time money transfer services to bank users, it becomes even more difficult to combat fraud, since banks have no time for triggering counteractivities in the event of fraudulent transactions.

By facilitating information exchanges, banks can improve their ability to detect and respond to fraud in real time. For example, if a bank that detected a potential or real fraudulent IBAN (International Bank Account Number) could share that information with others, those other banks could then take this information into account and prevent the fraudster from using this IBAN for other fraudulent transactions.

In France, between 2017 and 2018, there was a significant increase in the number of fraudulent checks introduced across the entire banking network. The fraudster used the same mode of operation, involving opening an account with a specific bank, crediting the account with a fraudulent cheque from another bank, and transferring the credited funds to yet another bank account, in order to finally withdraw the money at an ATM before the fraud was discovered.

## 2.1 The OBSIDIAN Open Banking Network

In order to develop a solution that adheres to European values and legislation, CyberSec4Europe developed OBSIDIAN, the *Open Banking Sensitive Data Sharing Network for Europe*, which allows banks to pseudonymously share relevant information – specifically, IBANs – coming from fraudulent activities without violating either their customers' privacy or their own business confidentiality requirements.

At a high level, the message and information flow is as specified in the following and as also depicted in Fig. 1.

- Firstly, a fraud expert or a fraud detection system within a bank, say Bank A, detects a suspicious transaction and wants to use the OBSIDIAN network to check whether the beneficiary's IBAN has already been used in fraudulent transactions at other banks.

- Bank A thus pseudonymizes the suspicious IBAN (blue box) and sends it to the OBSIDIAN server, which serves as a pure proxy towards all other participating banks.

- Upon receiving the request, Bank B and Bank C compute pseudonyms on their known fraudulent IBANs (green and orange boxes, respectively). Furthermore, they add another layer of pseudonyms on the received request.

- All responses from Bank B and Bank C are again routed through the OBSIDIAN server, which forwards them to Bank A.

- Bank A now adds another layer of pseudonyms on the responses of Bank B and Bank C, and finally performs a simple comparison as to whether any of the results match the received re-randomized requests. This requires the commutative property of the deployed pseudonymization scheme.
<figure><img src="image_3.png" /><figcaption>Fig. 1. OBSIDIAN overview</figcaption></figure>

## 2.2 Evaluation

The key objectives of the demonstrator were the protection of banking secrecy, GDPR compliance, usability, and EU-wide availability.

At a high level, the achievement of these properties can be seen as follows. Regarding *banking secrecy*, it is important to note that no bank in the system is able to identify the sender of a request. That is, in the example flow above, Bank B is unable to decide whether the request came from Bank A or from Bank C, as the OBSIDIAN server acts as a proxy that hides the origin of a request. On the other hand, for the same reason, Bank A is unable to decide which banks reacted to the request, and where a potential match originated from. Furthermore, no party except for Bank A – including the OBSIDIAN server – learns anything about the result of the comparison.

With respect to *GDPR compliance*, it is important to note that the OBSIDIAN server does not store any data. Due to the pseudonymization mechanisms deployed, no party in the process can access IBANs in plaintext. Finally, to be compliant with the right for erasure, banks could take back their data whenever necessary.

*Usability* is achieved in two ways. Firstly, the technology does not involve complex cryptographic mechanisms or similar, and is thus easy to understand by non-IT experts. Secondly, integration of the solution into existing ecosystems is relatively easy, as it only requires connecting one host within a bank with a single server.

Finally, *EU-wide availability* is achieved by the scalability of the system, as processing a request does not cause relevant computational overhead for any
party. Furthermore, by developing and testing the solution in Member States
with the most restrictive secrecy laws, applicability to other countries follows.
For instance, although the key information sources in the OBSIDIAN network
are IBANs – belonging to potential fraudsters, terrorists or money launderers
no less – in France an IBAN is considered to constitute personal data and as
such the French national data protection authority CNIL stipulated that the
exchange of IBANs would require the consent of the owners i.e., the potential
fraudsters, terrorists or money launderers. However, after repeated interventions
to overturn this ruling, the French authorities considered this added security a
good practice that would help minimise the data protection risks.

Within CyberSec4Europe, other approaches for achieving the same function-
ality were analyzed and considered, e.g., based on MISP<fnref n="2" /> (Malware Information
Sharing Platform) or blockchain technologies. For a detailed comparison, we refer
to the full evaluation report of our vertical [27].

3 Privacy-Preserving Identity Management

In an increasingly interconnected world, identity management systems offer
a convenient and user-friendly way for authentication towards a broad range
of application and systems. While in practice, such services are often offered
by major cloud providers, privacy-preserving identity management has gained
increasing attention in the academic world and beyond. The ambition of this
demonstrator was to showcase the applicability of such privacy-enhancing tech-
nologies also beyond the usual application domains, and specifically with regards
to job application portals.

On the one hand, there has been an increasing number of cases of faked
university diplomas in many countries around the globe, e.g., [15,28]. What is
therefore needed are efficient mechanisms to obtain strong guarantees about the
authenticity of claimed qualifications already at early stages of a hiring process,
in order to avoid unnecessary overhead, costs, and delays. On the other hand, it
is well known that there exists a relevant bias in the hiring process; for instance,
applicants are often discriminated against, because they belong to minorities [17].
Other discriminatory factors impacting the job market might include age [14] or
gender [2]. What would thus be important are job application processes that do
not reveal any sensitive information – like age, gender, or nationality – especially
in a pre-selection stage, in order to guarantee fairness and to fight discrimination.
The goal was therefore to develop an application portal that served the needs of
both employers and employees.

3.1 Portal Design

The key technology used to resolve the tension between the different
requirements were attribute-based credentials (or ABCs), first introduced by

<footnote n="2">² https://misp-project.org/.</footnote>
Chaum [10,11], and later refined and enhanced by various authors, leading, e.g., to prominent solutions like Microsoft's UProve [6,22] or IBM's Identity Mixer [7,9]. Further research in this area included, among others, [1,3,4,8,13,16]. In a nutshell, in an ABC system, users can receive digital certificates (so-called credentials) on personal attributes (e.g., name, date or place of birth) from an issuer. Later, they can selectively decide which attributes to reveal to a relying party and which attributes to keep confidential, while the relying party still obtains formal end-to-end authenticity guarantees on the disclosed attributes.

In our demonstrator, ABCs are now used to give students formal digital certificates on obtained degrees, certifying their name, date of birth, type of degree, date of issuance, etc. When applying for a job, they can now selectively decide which information to reveal (e.g., type and name of degree) and which information to keep private (e.g., name or date of birth), while still convincing the relying party that an original credential was used for this computation. In order to ensure that users are aware of the information they reveal, we used drag-and-drop as an affirmative action according to Karegar et al. [18]. The specific library being used for ABCs is the OLYMPUS implementation by Torres Moreno et al. [21] (Fig. 2).

<figure><img src="image_4.png" /><figcaption>Fig. 2. High-level architecture of the job application demonstrator.</figcaption></figure>

However, simply hiding certain attribute data from a diploma is by far not sufficient for a privacy-preserving job application process. As part of the development, an entire application portal was developed, guiding the applicant through all necessary steps, including the provisioning of standardized, anonymized template CVs asking only for the information relevant at pre-selection stage or
similar. For instance, by only asking for relevant work experience in the last five years, metadata leaks allowing one to derive an applicant's age from the work experience can be reduced. Other aspects to be considered included, for example, the communication interface from the hiring team to the applicant: for instance, requesting an email address for follow-up questions may already leak sensitive information such as the applicant's name, which in turn may give indications regarding gender or country of origin. As part of the application process, therefore a simple anonymous mailbox was set up, through which any further communication could take place. Furthermore, to also achieve privacy on the network layer, the TOR<fnref n="3" /> overlay network was used for all communication.

## 3.2 Evaluation

The main requirements for the demonstrator at hand can be clustered into the categories explained in the following.

Firstly, from an employer's point of view, it is important to ensure the *authenticity* of any received information in the application process. This directly follows from the soundness of the cryptographic primitives (i.e., attribute-based credential systems) being used.

On the other hand, to achieve *privacy* of applicants, several aspects need to be considered. From a technological point of view, ABC systems guarantee that undisclosed information is not leaked, by any means, to the relying party. Furthermore, different actions of the same user are fully unlinkable, i.e., if a user applies for different positions, this cannot be learned from the academic certificates being used. However, potential linkability through additional revealed information (e.g., contained in the CV) can only be avoided by strong education of applicants. Furthermore, it is worth noting that in the current implementation, the issuer of an academic degree is revealed due to the technology being used, which may not always be necessary in the first application round. This could be mitigated by using current techniques that allow hiding the issuer of credentials within a set of acceptable issuers [3, 5, 12].

Finally, regarding *usability*, we performed a study with more than 40 participants with different backgrounds. While most participants acknowledged the need for privacy-enhancing technologies in an online world, and despite having received detailed information material, guidelines, and briefings, many users still included sensitive information such as full names or nationality in documents uploaded to the application portal, thereby rendering parts of the privacy-guarantees of ABC systems meaningless. On the one hand, this shows a need for increasing user awareness, while on the other hand platforms need to give very clear guidelines and minimize the risk for accidental disclosure of information through the user.

For full details on the setup, requirements, and evaluation of the demonstrator, we refer the interested reader to [25–27].

<footnote n="3">³ https://www.torproject.org/.</footnote>
# 4 Smart Cities

Nowadays, most people worldwide live or work in cities, with the numbers tending to increase. So making cities comfortable and efficient environments in which people and businesses can thrive is a key issue in society. Following the trend towards digitisation and digitalisation, this is leading to many cities and metropolitan areas around the globe embracing the paradigm of “smart cities”. With this, they aim at enabling innovation, economic growth, and well-being, ultimately increasing the living quality in these regions, and palliating issues like increasing pollution and resource usage.

One first step in this direction requires connecting data consumers and producers, allowing service providers to find and use data from the city as well as third-party data providers to achieve their goals. Such data-based services may address a large variety of domains, including, for example, mobility, energy efficiency, health, sustainable housing, or digital public services. What all these areas have in common are strong requirements regarding data sovereignty, quality, security, and privacy.

Indeed, smart platforms need to avoid privacy leaks at multiple levels, from data shared to platform interactions. Additionally, a security platform should protect the heterogeneous systems that compose the smart city environment, maintaining the required level of trust. A key security element for both topics is the platform's authentication and authorization framework.

## 4.1 City of Murcia

MiMurcia, Murcia's smart city project, consists of the FIWARE platform<fnref n="4" />, which collects data from hundreds of sensors and other data sources such as parking service providers and public transport companies. The system includes, among others, information from agronomic sensors installed in parks and gardens, weather stations, noise sensors, traffic information, parking information, or public transport information.

Some of the potential applications of existing technologies and data range from reducing traffic congestion to improving the efficiency and sustainability of resource use (with particular interest in water resources) and the safety and overall well-being of citizens. In addition, promoting local commerce and improving interaction between city officials and citizens have also been identified as project objectives.

This demonstrator extended the security and privacy aspects of the existing platform by introducing a private identity management system that allows users to register and authenticate in the Smart-City ecosystem. Through this system, user privacy preferences are respected, and they can control how their personal information will be shared and used to identify them in the various services registered under the Smart-City project.

<footnote n="4">⁴ https://www.fiware.org/.</footnote>
Concretely, security tools based on XACML (eXtensible Access Control Markup Language) have been used to provide rule-based access control to the Smart City Platform data in conjunction with a self-sovereign privacy-preserving identity management solution based on OLYMPUS [21], to ensure that registered users (citizens, SMEs, and other services) have access to the Smart City Platform data. Smart-City data has been made available for search, discovery and access. Thus, the platform governs authorization through the XACML-based access control system, which is based on the DCapBAC model [23] and provides a distributed capability-based access control system. The integration of the identity management solution, and in particular its privacy-enhancing Attribute-Based Credentials (p-ABC), with this authorization framework enabled assurance of GDPR goals like minimal disclosure or non-traceability of user requests.

Additionally, a distributed ledger infrastructure (in particular, realized as Blockchain) was deployed to share, in a transparent and trustworthy manner, the public information necessary for the solution, from cryptographic material (e.g., public keys) to the services available and their approved access policies. This, along with the usage of the eIDAS framework as a source of a citizen's identity data, served to cement trust in the solution. Overall, the use of these technologies allowed us to provide privacy-friendly solutions that enable secure access to smart city data and services in the most efficient and flexible way, taking into account the diversity of devices and services in such a system.

A high-level view on the demonstrator architecture and main flow is given in Fig. 3.

<figure><img src="image_5.png" /><figcaption>Fig. 3. High-level architecture of the smart cities demonstrator.</figcaption></figure>
## 4.2 Evaluation

The test case executed in Murcia focused on the improvement of security and privacy aspects during interaction with the smart city platform, specifically for authentication and authorization. To validate the security, privacy and usability requirements, a two-fold validation strategy was followed: technical test cases and questionnaires with two target groups: developers and users. In the following, we give an overview on how they were addressed, and some insights coming from the evaluation process. For full details on the setup, requirements, and evaluation of the demonstrator, we refer the interested reader to [25–27].

From the platform’s point of view, the security of the authorization process is key. The demonstrator has successfully developed a complete scenario, including integration with the traditional and widespread XACML. Specifically, the authorization framework is fully integrated with XACML access policies, with complex checks based on the Zero-Knowledge proofs of p-ABCs being possible. The security properties of p-ABCs ensure the authenticity of the presented data. What is more, the registration process improves trust in identity data through the use of eIDAS. However, this showed the limitations of current eIDAS, as its deployments failed to fulfil the necessities of most real-world applications, for example, with reduced availability of identity information, in some cases not even including the attributes deemed as mandatory, or lack of privacy mechanisms.

Users, on the other hand, want to be able to access the platform’s services while their privacy is ensured. This has been achieved thanks to the properties of the p-ABC scheme used for authentication, which allow minimal disclosure and unlinkability. This work also showcased a remarkable issue in this field: the immaturity of standardization. W3C’s Verifiable Credentials are the leading standardization element for p-ABC scenarios, but even in that case the structures for Zero-Knowledge-based authentication are sorely lacking, which implies further work is needed [24].

<figure><img src="image_6.png" /><figcaption>**Fig. 4.** Time taken for the various processes of authentication and authorization.</figcaption></figure>
Lastly, for it to be applicable in practice, the system needs to have proper usability. Technical tests were used to achieve feasibility benchmarks for various processes (from enrolment to access through PEP), as shown in Fig. 4. Further, questionnaires have shown user insights on the feel of the solution, as well as the demonstrator and privacy topics in general. The results were positive, with approval criteria being met (e.g., percentage of people satisfied with the solution's approach for user consent), and came alongside interesting feedback for further improvements, such as “look-and-feel” of the system. Additionally, as one of the key findings, users overwhelmingly preferred technology enforced privacy solutions over relying on adhering to policies by service providers, which encourages further work on the topic.

# 5 Conclusions

In this workshop, we presented an overview of recent developments within the H2020 CyberSec4Europe project. Specifically, we presented three vertical demonstrators from different domains – open banking, privacy-preserving identity management, and smart cities. For each of the domains, we detailed the specific privacy requirements, and presented CyberSec4Europe’s approach to address them. All demonstrators were evaluated in depth together with relevant stakeholders, and the resulting findings have been specified in detail in [27], from which also contributions to the project’s research roadmaps and recommendations for further research have been derived [19,20].

**Acknowledgements.** The work leading to this workshop was funded by the European Union under the H2020 Programme Grant Agreement No. 830929 (CyberSec4Europe).

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