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Jordi Herrera-Joancomartí

Bio: Jordi Herrera-Joancomartí is an academic researcher from Autonomous University of Barcelona. The author has contributed to research in topics: Digital watermarking & Cryptocurrency. The author has an hindex of 24, co-authored 102 publications receiving 1772 citations. Previous affiliations of Jordi Herrera-Joancomartí include Multimedia University & Open University of Catalonia.


Papers
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Book ChapterDOI
03 Mar 2014
TL;DR: Measurements of the P2P network can be considered as a lower bound for Bitcoin usage, and they provide interesting results on the adoption of such virtual currency.
Abstract: The Bitcoin virtual currency is built on the top of a decentralized peer-to-peer (P2P) network used to propagate system information such as transactions or blockchain updates. In this paper, we have performed a data collection process identifying more than 872000 different Bitcoin nodes. This data allows us to present information on the size of the Bitcoin P2P network, the node geographic distribution, the network stability in terms of interrupted availability of nodes, as well as some data regarding the propagation time of the transmitted information. Furthermore, although not every Bitcoin user can be identified as a P2P network node, measurements of the P2P network can be considered as a lower bound for Bitcoin usage, and they provide interesting results on the adoption of such virtual currency.

147 citations

Journal ArticleDOI
TL;DR: A wide analysis on the expenses of launching symmetric and asymmetric cryptographic algorithms, hash chain functions, elliptic curves cryptography and pairing based cryptography on personal agendas, and compared with the costs of basic operating system functions shows that although cryptographic power costs are high and such operations shall be restricted in time, they are not the main limiting factor of the autonomy of a device.
Abstract: Networks are evolving toward a ubiquitous model in which heterogeneous devices are interconnected. Cryptographic algorithms are required for developing security solutions that protect network activity. However, the computational and energy limitations of network devices jeopardize the actual implementation of such mechanisms. In this paper, we perform a wide analysis on the expenses of launching symmetric and asymmetric cryptographic algorithms, hash chain functions, elliptic curves cryptography and pairing based cryptography on personal agendas, and compare them with the costs of basic operating system functions. Results show that although cryptographic power costs are high and such operations shall be restricted in time, they are not the main limiting factor of the autonomy of a device.

101 citations

Book ChapterDOI
10 Sep 2014
TL;DR: This paper provides a comprehensive description on the details that make bitcoin anonymity an interesting research topic in the privacy community and performs an exhaustive review of the bitcoin anonymity research papers published so far.
Abstract: Bitcoin has emerged as the most successful crypto currency since its appearance back in 2009. Besides its security robustness, two main properties have probably been its key to success: anonymity and decentralization. In this paper, we provide a comprehensive description on the details that make such cryptocurrency an interesting research topic in the privacy community. We perform an exhaustive review of the bitcoin anonymity research papers that have been published so far and we outline some research challenges on that topic.

97 citations

Book ChapterDOI
26 Feb 2018
TL;DR: This paper introduces a tool to study and analyze the UTXO set, along with a detailed description of the set format and functionality, and quantifies the difference between the two existing formats up to the date.
Abstract: Bitcoin relies on the Unspent Transaction Outputs (UTXO) set to efficiently verify new generated transactions. Every unspent output, no matter its type, age, value or length is stored in every full node. In this paper we introduce a tool to study and analyze the UTXO set, along with a detailed description of the set format and functionality. Our analysis includes a general view of the set and quantifies the difference between the two existing formats up to the date. We also provide an accurate analysis of the volume of dust and unprofitable outputs included in the set, the distribution of the block height in which the outputs where included, and the use of non-standard outputs.

89 citations

Journal ArticleDOI
TL;DR: A novel protocol specially designed to protect the users' privacy in front of web search profiling is presented, which provides a distorted user profile to the web search engine and provides an affordable overhead while offering privacy benefits to the users.

89 citations


Cited by
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01 Apr 1997
TL;DR: The objective of this paper is to give a comprehensive introduction to applied cryptography with an engineer or computer scientist in mind on the knowledge needed to create practical systems which supports integrity, confidentiality, or authenticity.
Abstract: The objective of this paper is to give a comprehensive introduction to applied cryptography with an engineer or computer scientist in mind. The emphasis is on the knowledge needed to create practical systems which supports integrity, confidentiality, or authenticity. Topics covered includes an introduction to the concepts in cryptography, attacks against cryptographic systems, key use and handling, random bit generation, encryption modes, and message authentication codes. Recommendations on algorithms and further reading is given in the end of the paper. This paper should make the reader able to build, understand and evaluate system descriptions and designs based on the cryptographic components described in the paper.

2,188 citations

Journal ArticleDOI
TL;DR: The blockchain taxonomy is given, the typical blockchain consensus algorithms are introduced, typical blockchain applications are reviewed, and the future directions in the blockchain technology are pointed out.
Abstract: Blockchain has numerous benefits such as decentralisation, persistency, anonymity and auditability. There is a wide spectrum of blockchain applications ranging from cryptocurrency, financial services, risk management, internet of things (IoT) to public and social services. Although a number of studies focus on using the blockchain technology in various application aspects, there is no comprehensive survey on the blockchain technology in both technological and application perspectives. To fill this gap, we conduct a comprehensive survey on the blockchain technology. In particular, this paper gives the blockchain taxonomy, introduces typical blockchain consensus algorithms, reviews blockchain applications and discusses technical challenges as well as recent advances in tackling the challenges. Moreover, this paper also points out the future directions in the blockchain technology.

1,928 citations

Journal ArticleDOI
03 Oct 2016-PLOS ONE
TL;DR: The objective is to understand the current research topics, challenges and future directions regarding Blockchain technology from the technical perspective, and recommendations on future research directions are provided for researchers.
Abstract: Blockchain is a decentralized transaction and data management technology developed first for Bitcoin cryptocurrency. The interest in Blockchain technology has been increasing since the idea was coined in 2008. The reason for the interest in Blockchain is its central attributes that provide security, anonymity and data integrity without any third party organization in control of the transactions, and therefore it creates interesting research areas, especially from the perspective of technical challenges and limitations. In this research, we have conducted a systematic mapping study with the goal of collecting all relevant research on Blockchain technology. Our objective is to understand the current research topics, challenges and future directions regarding Blockchain technology from the technical perspective. We have extracted 41 primary papers from scientific databases. The results show that focus in over 80% of the papers is on Bitcoin system and less than 20% deals with other Blockchain applications including e.g. smart contracts and licensing. The majority of research is focusing on revealing and improving limitations of Blockchain from privacy and security perspectives, but many of the proposed solutions lack concrete evaluation on their effectiveness. Many other Blockchain scalability related challenges including throughput and latency have been left unstudied. On the basis of this study, recommendations on future research directions are provided for researchers.

1,528 citations

Journal ArticleDOI
TL;DR: This survey unroll and structure the manyfold results and research directions of Bitcoin, and deduce the fundamental structures and insights at the core of the Bitcoin protocol and its applications.
Abstract: Besides attracting a billion dollar economy, Bitcoin revolutionized the field of digital currencies and influenced many adjacent areas. This also induced significant scientific interest. In this survey, we unroll and structure the manyfold results and research directions. We start by introducing the Bitcoin protocol and its building blocks. From there we continue to explore the design space by discussing existing contributions and results. In the process, we deduce the fundamental structures and insights at the core of the Bitcoin protocol and its applications. As we show and discuss, many key ideas are likewise applicable in various other fields, so that their impact reaches far beyond Bitcoin itself.

1,193 citations