"An Analysis of Anonymity in Bitcoin Using P2P Network ...

Research Paper - An Analysis of Anonymity in Bitcoin Using P2P Network Traffic

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Research Paper - An Analysis of Anonymity in Bitcoin Using P2P Network Traffic

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TxProbe: Discovering Bitcoin's Network Topology Using Orphan Transactions

arXiv:1812.00942
Date: 2018-12-10
Author(s): Sergi Delgado-Segura, Surya Bakshi, Cristina Pérez-Solà, James Litton, Andrew Pachulski, Andrew Miller, Bobby Bhattacharjee

Link to Paper


Abstract
Bitcoin relies on a peer-to-peer overlay network to broadcast transactions and blocks. From the viewpoint of network measurement, we would like to observe this topology so we can characterize its performance, fairness and robustness. However, this is difficult because Bitcoin is deliberately designed to hide its topology from onlookers. Knowledge of the topology is not in itself a vulnerability, although it could conceivably help an attacker performing targeted eclipse attacks or to deanonymize transaction senders. In this paper we present TxProbe, a novel technique for reconstructing the Bitcoin network topology. TxProbe makes use of peculiarities in how Bitcoin processes out of order, or "orphaned" transactions. We conducted experiments on Bitcoin testnet that suggest our technique reconstructs topology with precision and recall surpassing 90%. We also used TxProbe to take a snapshot of the Bitcoin testnet in just a few hours. TxProbe may be useful for future measurement campaigns of Bitcoin or other cryptocurrency networks.

References
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Dandelion++: Lightweight Cryptocurrency Networking with Formal Anonymity Guarantees

arXiv:1805.11060
Date: 2018-05-28
Author(s): Giulia Fanti, Shaileshh Bojja Venkatakrishnan, Surya Bakshi, Bradley Denby, Shruti Bhargava, Andrew Miller, Pramod Viswanath

Link to Paper


Abstract
Recent work has demonstrated significant anonymity vulnerabilities in Bitcoin's networking stack. In particular, the current mechanism for broadcasting Bitcoin transactions allows third-party observers to link transactions to the IP addresses that originated them. This lays the groundwork for low-cost, large-scale deanonymization attacks. In this work, we present Dandelion++, a first-principles defense against large-scale deanonymization attacks with near-optimal information-theoretic guarantees. Dandelion++ builds upon a recent proposal called Dandelion that exhibited similar goals. However, in this paper, we highlight simplifying assumptions made in Dandelion, and show how they can lead to serious deanonymization attacks when violated. In contrast, Dandelion++ defends against stronger adversaries that are allowed to disobey protocol. Dandelion++ is lightweight, scalable, and completely interoperable with the existing Bitcoin network. We evaluate it through experiments on Bitcoin's mainnet (i.e., the live Bitcoin network) to demonstrate its interoperability and low broadcast latency overhead.

References
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Delightful Privacy

Delightful Privacy delightful

This is a collection of software, operating systems, and other miscellaneous tools to help the average user fight for their privacy and security online.

Operating Systems

Fedora

Fedora uses Security-Enhanced Linux by default, which implements a variety of security policies, including mandatory access controls, which Fedora adopted early on. Fedora provides a hardening wrapper, and does hardening for all of its packages by using compiler features such as position-independent executable (PIE). Wikipedia

Pop!_OS

Pop!_OS provides full out-of-the-box support for both AMD and Nvidia GPUs. It is regarded as an easy distribution to set-up for gaming, mainly due to its built-in GPU support. Pop!_OS provides default disk encryption, streamlined window and workspace management, keyboard shortcuts for navigation as well as built in power management profiles. The latest releases also have packages that allow for easy setup for TensorFlow and CUDA. Wikipedia

Debian

Debian is one of the oldest operating systems based on the Linux kernel. The project is coordinated over the Internet by a team of volunteers guided by the Debian Project Leader and three foundational documents: the Debian Social Contract, the Debian Constitution, and the Debian Free Software Guidelines. New distributions are updated continually, and the next candidate is released after a time-based freeze. Wikipedia

openSUSE Tumbleweed - Rolling Release!

Any user who wishes to have the newest packages that include, but are not limited to, the Linux Kernel, SAMBA, git, desktops, office applications and many other packages, will want Tumbleweed. openSUSE

For enhanced security

Qubes OS

Qubes OS is a security-focused desktop operating system that aims to provide security through isolation. Virtualization is performed by Xen, and user environments can be based on Fedora, Debian, Whonix, and Microsoft Windows, among other operating systems. Wikipedia

Tails

Tails, or The Amnesic Incognito Live System, is a security-focused Debian-based Linux distribution aimed at preserving privacy and anonymity. All its incoming and outgoing connections are forced to go through Tor, and any non-anonymous connections are blocked. Wikipedia).*

Whonix

Whonix is a Debian GNU/Linux–based security-focused Linux distribution. It aims to provide privacy, security and anonymity on the internet. The operating system consists of two virtual machines, a "Workstation" and a Tor "Gateway", running Debian GNU/Linux. All communications are forced through the Tor network to accomplish this. Wikipedia

Web Browsers

For Desktop

Firefox Needs manual tweaking to be more secure! Use ghacks

Firefox, is a free and open-source web browser developed by the Mozilla Foundation and its subsidiary, the Mozilla Corporation. Wikipedia Recommended addons: uBlock Origin | Https Everywhere | Privacy Badger | Privacy Possum | Decentraleyes | NoScript | CanvasBlocker

Tor

Tor is free and open-source software for enabling anonymous communication. The name derived from the acronym for the original software project name "The Onion Router". Tor directs Internet traffic through a free, worldwide, volunteer overlay network consisting of more than seven thousand relays to conceal a user's location and usage from anyone conducting network surveillance or traffic analysis. Using Tor makes it more difficult to trace Internet activity to the user. Wikipedia

UnGoogled-Chromium

Without signing in to a Google Account, Chromium does pretty well in terms of security and privacy. However, Chromium still has some dependency on Google web services and binaries. In addition, Google designed Chromium to be easy and intuitive for users, which means they compromise on transparency and control of internal operations.
ungoogled-chromium addresses these issues in the following ways:

For mobile

Bromite Android Only

Bromite is a Chromium fork with ad blocking and privacy enhancements; take back your browser! Bromite

Firefox Focus Android - iOS

Firefox Focus is a free and open-source privacy-focused browser from Mozilla, available for Android and iOS. Wikipedia

Tor Browser for mobile Android - iOS

Tor protects your privacy on the internet by hiding the connection between your Internet address and the services you use. We believe Tor is reasonably secure, but please ensure you read the instructions and configure it properly. GitHub

Email

Tutanota

Tutanota is an end-to-end encrypted email software and freemium hosted secure email service. Wikipedia

Mailbox

There are many ears listening on the Internet, which is why all our services require mandatory SSL/TLS-encrypted data transmission. For additional security, we also use enhanced (green) security certificates ("EV") by the independent SwissSign trust service provider from Switzerland (Check the padlock symbol in your web browser's URL field). But this is just the beginning – there is so much more that we do. Mailbox

Disroot

Disroot is a decentralized cloud-based service that allows you to store your files and communicate with one another. Established by a privacy-focused organization of volunteers, if we look at Disroot as an email provider specifically, it stands out thanks to its emphasis on security with a completly free open-source approach. ProPrivacy

ProtonMail

ProtonMail is an end-to-end encrypted email service founded in 2013 in Geneva, Switzerland by scientists who met at the CERN research facility. ProtonMail uses client-side encryption to protect email content and user data before they are sent to ProtonMail servers, unlike other common email providers such as Gmail and Outlook.com. The service can be accessed through a webmail client, the Tor network, or dedicated iOS and Android apps. Wikipedia

Search Engine

Searx

searx is a free metasearch engine, available under the GNU Affero General Public License version 3, with the aim of protecting the privacy of its users. To this end, searx does not share users' IP addresses or search history with the search engines from which it gathers results. Tracking cookies served by the search engines are blocked, preventing user-profiling-based results modification. By default, searx queries are submitted via HTTP POST, to prevent users' query keywords from appearing in webserver logs. Wikipedia - Find public instances of searx here searx.space

Startpage

Startpage is a web search engine that highlights privacy as its distinguishing feature. Previously, it was known as the metasearch engine Ixquick, At that time, Startpage was a variant service. Both sites were merged in 2016. Wikipedia

YaCy

YaCy is a free distributed search engine, built on principles of peer-to-peer (P2P) networks. Its core is a computer program written in Java distributed on several hundred computers, as of September 2006, so-called YaCy-peers. Each YaCy-peer independently crawls through the Internet, analyzes and indexes found web pages, and stores indexing results in a common database (so called index) which is shared with other YaCy-peers using principles of P2P networks. It is a free search engine that everyone can use to build a search portal for their intranet and to help search the public internet clearly. Wikipedia

VPN

If you need anonymity and privacy online use Tor instead, if you are looking to bypass a geo-restriction, don't trust public WiFi, or are looking to Torrent, a VPN will help you.

Mullvad

Mullvad is an open-source commercial virtual private network (VPN) service based in Sweden. Launched in March 2009, Mullvad operates using the WireGuard and OpenVPN protocols. Mullvad accepts Bitcoin and Bitcoin Cash for subscriptions in addition to conventional payment methods.
No email address or other identifying information is requested during Mullvad's registration process. Rather, a unique 16-digit account number is anonymously generated for each new user. This account number is henceforth used to log in to the Mullvad service.
The TechRadar review notes that "The end result of all this is you don't have to worry about how Mullvad handles court requests to access your usage data, because, well, there isn't any." Wikipedia

ProtonVPN

ProtonVPN utilizes OpenVPN (UDP/TCP) and the IKEv2 protocol, with AES-256 encryption. The company has a strict no-logging policy for user connection data, and also prevents DNS and Web-RTC leaks from exposing users' true IP addresses. ProtonVPN also includes Tor access support and a kill switch to shut off Internet access in the event of a lost VPN connection.
In January 2020, ProtonVPN became the first VPN provider to release its source code on all platforms and conduct an independent security audit. ProtonVPN is the only VPN to do so, even though experts say this is a crucial factor in deciding whether to trust a VPN service. Wikipedia

For information about alternatives to software and services.

If you are looking for alternatives to proprietary services like Discord and Facebook, or an open-source alternative to Photoshop, check out our list about Awesome-Alternatives

Mirrors are kept up to date, this post may lag behind as we add stuff in.

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How crazy is this? (A protocol for metadata obfuscation)

Alice and Bob want to have a private conversation but they also don't want anyone to know they're talking to each other.
I'm assuming that they can use some public key cryptography protocol that's sufficient to ensure their conversation is indeed private. Alice encrypts her messages using Bob's public key, and her encrypted messages can only be decrypted with Bob's private key.
But what about the metadata, ie the who/what/when/where information that we now know is collected routinely by the NSA, and which allows an adversary to determine that Alice and Bob are in communication?
As I understand it, there are several more or less practical ways to obscure the metadata -- including the identity of the intended recipient -- of Alice's and Bob's messages. These methods include steganography, TOpluggable transports, anonymizing email services and metadata encryption. But all of these approaches have weaknesses (eg trust issues, the existence of a central point of attack, susceptibility to traffic analysis), and as long as Alice's messages are ultimately being delivered to Bob (and vice versa), then any adversary who could discover this would know that Alice and Bob were in communication.
But what if Alice sent her encrypted messages not only to Bob, but to everyone ( * )? And everyone received them ( ** )? Public key encryption would ensure that only Bob would be able to actually decrypt and read the message, and meanwhile even an adversary with complete access to the entire network between Alice's and Bob's machines would still be unable to determine which particular instance of 'everyone' was the intended recipient. In other words, from the outside, an adversary would not be able to determine who Alice was talking to.
( * ) 'Everyone' here means 'everyone who's participating in this protocol'. Obviously, as with TOR, the more participants the better. This protocol would be trivially useless with only two users. But even three users would provide some protection. (Is Alice talking to Bob or to Carol?) And it would work a whole lot better if Bob were literally one in a million.
( ** ) Or rather: everyone's machine/device automatically received them. Each machine/device would then attempt to decrypt all incoming messages, and non-decipherable messages would automatically be discarded(***). The user would only be notified if the message was in fact for them.
(***) Or, more efficiently, be forwarded to a swarm of peers in a process that would be analogous to seeding a torrent.
If widely adopted, a protocol like this would presumably generate an insane amount of network traffic. Perhaps it might place an impossible, exponentially growing burden on the internet's infrastructure? I dunno. I also don't know if this could be mitigated by having each message be 'broadcast' using a P2P-like protocol? In any case, it's also going to be very resource intensive for every participating machine/device -- but then again, doesn't everyone who isn't mining bitcoins usually have countless unused CPU cycles on their machines?
Speaking of massive waste... you could also use this protocol to conceal the identity of the sender if everyone's device was set to automatically generate and send out a continual stream of dummy encrypted messages. And again, perhaps the absolute number of dummy messages could somehow be managed by recycling discarded messages back out into the swarm. (Even if this is possible, I think this kind of recycling would have to be done carefully, but I don't want to get into the details here.)
So what do you guys think? Is it so crazy it just might work? Or just plain crazy? Am I mischaracterizing the problem or the solution or missing some really obvious flaw?
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Hijacking Bitcoin: Routing Attacks on Cryptocurrencies

arXiv:1605.07524
Date: 2017-03-24
Author(s): Maria Apostolaki, Aviv Zohar, Laurent Vanbever

Link to Paper


Abstract
As the most successful cryptocurrency to date, Bitcoin constitutes a target of choice for attackers. While many attack vectors have already been uncovered, one important vector has been left out though: attacking the currency via the Internet routing infrastructure itself. Indeed, by manipulating routing advertisements (BGP hijacks) or by naturally intercepting traffic, Autonomous Systems (ASes) can intercept and manipulate a large fraction of Bitcoin traffic. This paper presents the first taxonomy of routing attacks and their impact on Bitcoin, considering both small-scale attacks, targeting individual nodes, and large-scale attacks, targeting the network as a whole. While challenging, we show that two key properties make routing attacks practical: (i) the efficiency of routing manipulation; and (ii) the significant centralization of Bitcoin in terms of mining and routing. Specifically, we find that any network attacker can hijack few (<100) BGP prefixes to isolate ~50% of the mining power---even when considering that mining pools are heavily multi-homed. We also show that on-path network attackers can considerably slow down block propagation by interfering with few key Bitcoin messages. We demonstrate the feasibility of each attack against the deployed Bitcoin software. We also quantify their effectiveness on the current Bitcoin topology using data collected from a Bitcoin supernode combined with BGP routing data. The potential damage to Bitcoin is worrying. By isolating parts of the network or delaying block propagation, attackers can cause a significant amount of mining power to be wasted, leading to revenue losses and enabling a wide range of exploits such as double spending. To prevent such effects in practice, we provide both short and long-term countermeasures, some of which can be deployed immediately.

References
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A Tale of Two Bitcoins Bitcoin Mega and Sub-Units Explained: centiBit, uBTC, mBTC, hBTC, fBTC, pBTC and more 28c3: Bitcoin - An Analysis PWLTO#1 – John-Alan Simmons on Chord: A Scalable P2P Lookup Service for Internet Applications Anonymity in the Bitcoin Peer-to-Peer Network by Giulia Fanti [PWLConf 2019]

Over the last 4 years, Bitcoin, a decentralized P2P crypto-currency, has gained widespread attention. The ability to create pseudo-anonymous financial transactions using bitcoins has made the currency attractive to users who value their privacy. Although previous work has analyzed the degree of anonymity Bitcoin offers using clustering and flow analysis, none have demonstrated the ability to ... Download Citation An Analysis of Anonymity in Bitcoin Using P2P Network Traffic Over the last 4 years, Bitcoin, a decentralized P2P crypto-currency, has gained widespread attention. The ... Bibliographic details on An Analysis of Anonymity in Bitcoin Using P2P Network Traffic. An Analysis of Anonymity in Bitcoin Using P2P Network Traffic. Erstes Kapitel lesen. Autoren: Philip Koshy, Diana Koshy, Patrick McDaniel Verlag: Springer Berlin Heidelberg Erschienen in: Financial Cryptography and Data Security » Jetzt Zugang zum Volltext erhalten. Abstract. Over the last 4 years, Bitcoin, a decentralized P2P crypto-currency, has gained widespread attention. The ability to ... DOI: 10.1007/978-3-662-45472-5_30 Corpus ID: 225868. An Analysis of Anonymity in Bitcoin Using P2P Network Traffic @inproceedings{Koshy2014AnAO, title={An Analysis of Anonymity in Bitcoin Using P2P Network Traffic}, author={P. Koshy and Diana Koshy and P. McDaniel}, booktitle={Financial Cryptography}, year={2014} }

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A Tale of Two Bitcoins

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