In this physical space, attendees will formalize procedures to register their presence, such as individuals scanning each other's QR codes and, by that act, generating an anonymous credential or token Borge et al. These credentials can then be utilized to establish membership in online communities.
In essence, pseudonym parties act as a framework for individuals to conduct reverse Turing tests on each other. For as long as hyper-realistic digital forgeries deep fakes remain in the Uncanny Valley Mori et al. This is especially true if utilized in combination with AI-hard tests, which require human interpretation. In these combined approaches, users willing to be authenticated need to perform the test simultaneously.
Thus, due to the fact that the same person cannot perform two actions at the same time, the protocol ensures the singularity of authentication. Pseudonym parties provide significant accountability since membership rights are limited and therefore can be revoked while preserving a relatively high degree of anonymity since credentials do not need to contain any personally identifiable information. There are also concerns regarding the authentication of users in remote or faraway locations who may not be able to attend physical gatherings.
This friction may be minimized by leveraging existing gatherings such as conferences, rituals, and civic ceremonies for identity authentication Ford, as well as through virtual pseudonym parties. A Web of Trust consists of identity certificates that can be digitally signed by other users who, by that act, declare the certificate valid and thus provide Proof of Personhood.
Through this process, the nodes of the network are effectively partitioned into Sybils and non-Sybils Viswanath et al. The Web of Trust paradigm relies on the fact that, while an attacker may be able to arbitrarily create Sybil identities in social networks, it will be much harder to substantiate said identities with an arbitrarily large number of false connections to trusted nodes Viswanath et al.
Sybil nodes will thus be poorly connected to the trusted network and easily identified. Web of trust schemes may be further reinforced by a reputation system that serves to track trust levels and prevent deception Dunphy and Petitcolas, We note that there have been attempts to create a web of trust framework through automated graph analysis of existing social trust networks, particularly social media networks.
One such approach is SybilRank, which aims to identify fake accounts within bounded social media networks and has met some success Cao et al. However, it is unlikely that widely used online social networks are good candidates for large-scale identity approaches, particularly for sensitive applications like civic engagement. Despite the long-term interest in Web of Trust, with the first limited-scope version set out in the second PGP manual in , several inherent issues with the approach have prevented its large-scale adoption.
First, a combination of different claims and credentials may not entirely guarantee Sybil-resistance Wang and De Filippi, Furthermore, levels of trust cannot be easily quantified, and only first-degree relationships can be fully trusted, which can constrain the network. Similar to pseudonym parties, these issues can also prevent users from low-infrastructure or remote locations from acquiring key signs or building in-network credibility Wilson and Giuseppe, To correct for these issues, the web of trust paradigm has been adapted, extended, and paired with other approaches, notably in the form of mutual surety graphs as well as graphs with other topological features Shahaf et al.
Two of the implementations that we will discuss also aim to extend the subjectivities of the web of trust approach, moving toward a more intersectional paradigm, as described below Immorlica et al. Intersectional Identity is a framework that aims to bridge formal verification methodologies and the informal mechanisms through which individuals check the validity of identity-related claims.
It builds upon traditional Web of Trust schemes by expanding the scope of markers that can be taken into account, such as one's name, age, address, gps history, interactions, skills, work, education, etc. All of these different markers can be translated into bits, so any given individual is associated with an exponentially large number of potential bits that may be useful for authentication. Here sociality refers to the fact that every aspect of identity is shared.
Redundancy denotes that the uniqueness of an individual is over-determined by the countless unique intersections of groups or sources of trust that each person finds themselves in through the course of their lives. With data architectures put in place to record intersectional markers, Sybil-resistant identities can be established by tracking just a few characteristics that uniquely identify an individual while keeping sensitive information private Immorlica et al.
The Token Curated Registry TCR , in contrast to the schemes outlined above, was not originally devised as a method for identity verification. In essence, TCRs draw from work on incentive systems designed to replace list owners through the creation of economic incentives for decentralized list curation. In this scheme, members of a registry hold tokens associated with the list, which may increase in value if they are able to maintain its quality, legitimacy, or popularity, thus attracting more list applicants who want to add their data to it Asgaonkar and Bhaskar, Members can establish trust through different mechanisms, such as staking a certain amount of funds, voting, or vouching for other members accurately.
TCRs have successfully been applied toward curating professional profiles, media content, and other services and are particularly instrumental in enabling decentralized courts for blockchain-based dispute resolution frameworks Lasaege et al.
Building upon these successes, different identity solutions employ this mechanism to create an incentive for members of an identity registry to go through the effort of verifying each other's uniqueness and singularity.
DAOs are a class of smart contract Norta, 16 devised to automate the execution of organizational governance and fund allocation. In that sense, these contracts may be thought of as an automated constitution. This organizational framework emerged as a possibility due to the creation of Ethereum, a blockchain network that permits Turing-complete computations 17 Minks, , leading to the growth of smart contract development.
By deploying DAO contracts into the Ethereum blockchain, organizations allow their participants to pool funds denominated in cryptocurrencies , maintain real-time control of resources, and vote on resource allocation to different projects with governance rules that are formalized, automated, and enforced by the conditions encoded into the smart contract.
This type of organizational framework is employed, in different ways, by several of the Proof of Personhood protocols described in this review. In contrast to the majority of smart contracts, which serve strictly financial purposes, DAOs are highly likely to entail human decision-making in their functioning. We now outline the approaches of these new and natively digital sources of authentication—their attributes, methodologies, strengths, and weaknesses—and sketch out possible directions for future developments.
Idena is an open-source project created by an anonymous group of engineers and computer scientists. It has its own blockchain, which is driven by a proof-of-person consensus, with every node linked to a cryptoidentity with equal voting power —thus, it is a fully decentralized solution. To join the network, participants must attend live authentication ceremonies held simultaneously for the entire network.
During these synchronous events, one must complete a set of FLIP tests within a limited amount of time. Afterwards, users are required to create new tests. FLIPs are instead always created by humans. The frequency of those authentication ceremonies is determined by the size of the network—currently they are conducted around once every 2 weeks. Given that tests cannot be solved by existing AI, Idena successfully provides a proof of personhood. However, it is not strictly anti-Sybil, with a probabilistic margin of error: although highly unlikely, a person with exceptional ability could solve more than one set of FLIPS within their allotted time, thus earning more valid identities within the network.
As an additional layer of security, Idena requires new members to present an invite code to be able to join their first authentication ceremony. This code can only be obtained through existing members, thereby creating a Web of Trust. Launched in August , to date the Idena Network has been able to validate 4, identities Their approach presents a significant advance for the research and development concerned with natively digital identity protocols.
Furthermore, the protocol protects privacy, as it involves no data point except that of proof of conscious cognitive ability. The most salient tradeoff in this system is the significantly high coordination cost to achieve recurrent, simultaneous solving of FLIPS: all nodes must continuously participate in the synchronous events; otherwise, their identities expire. Additionally, it remains to be seen whether Idena's Sybil-resistance strategy will be able to weather the dynamic development of AI connected with neural networks and deep learning.
Humanity DAO is an Ethereum-based protocol. It was designed to incentivize a set of economic actors to maintain a registry of unique human identities without a central authority 20 and leveraged existing work on Token Curated Registries Asgaonkar and Bhaskar, In Humanity DAO's case, holders evaluate candidate identities and deem them legitimate through consensus-based voting. The protocol consists of the following steps:.
Applicants made a request to join the list using their social media profile information. Applicants staked a fee on their candidacy. If the applicant got rejected, the application fee was ceded. Members of the list voted on whether the new applicant should be included based on the submitted profile. Members were incentivized to curate the list honestly in order to generate demand from new applicants, leading to a long-term sustainability of the project.
The registry had a method called is Human that any smart contract could query to see whether a given Ethereum address had been confirmed as a unique human. Launched in May , the project quickly gained rapid traction, reaching around approved members and being adopted by many influential figures within the Ethereum network; however, growth stagnated after the initial community of early adopters from the network was saturated.
As related to us by the founder, this resulted in Humanity DAO suffering various forms of attacks, including one in which a change to the smart contract made it prohibitively expensive for new applicants to join.
These repeated attacks led to the eventual termination of the project in January Kleros is an Ethereum-based protocol for decentralized dispute resolution. Kleros' approach distinguishes itself by appending to the functioning of its protocol a recourse to adjudicate cases of faulty or duplicate users.
This is done through distributed dispute resolution systems such as the Kleros Court 22 or if decided by members through the registry's internal governance, other alternatives such as Aragon's courts Within the Proof of Humanity protocol, users can vouch for each other with a certain amount of financial stake. To incentivize the maintenance of the registry, vouching deposits serve as a bounty, available for anyone able to correctly identify false positives in the registry.
If a member vouches for users that are later determined to be duplicate or false by the distributed court, they are punished in the form of being removed from the registry and losing their vouching deposit, thus discouraging such attacks Lasaege et al. While this protocol has significant promise in building an effective reputation-based web of trust with tools in place to adjudicate cases in which the singularity of an identity is disputed, it compromises the biometric information of members by requiring a video selfie and other additional information, which may de-incentivize potential users.
Upala is an Ethereum-based protocol designed to be interoperable with DAOs Its social graph consists of verification groups that assign a score for each member, denominated in currency; this gives members the right to steal from the shared pool of the group they belong to, the amount of their score. Thus, this model implements the social responsibility concept, in which groups are incentivized to develop approval mechanisms that lead toward having highly trusted members.
Any existing DAO may fit into the Upala protocol, given that members are willing to trust each other by collateralizing funds in exchange for distributing reputation. Groups can be also be composed by direct end users or other groups—thus combining uniqueness scores into larger pools. This framework generates a market for identity authentication where on the supply side groups are trying to gather as many users as possible through subgroups or directly , with the highest reputation i.
The Upala model expands on the principles behind a Token Curated Registry where members are incentivized to maintain a high-quality list and also employs an intersectional lens by enabling different schemes to be created and combined within its protocol.
Given that the uniqueness scores are, to a certain extent, relative to pooled funds, this may lead to capital-rich users having ease in obtaining higher scores—although groups may establish different verification mechanisms capable of placating this vulnerability. Another major vulnerability encoded within this model would be an avalanche user exit: if an event leads to loss of trust in Upala, an avalanche of individuals may explode their identities in panic to seize assets, ignoring the reputation consequences.
However, it is possible that the probability of such a scenario materializing decreases as trust consolidates within the system, with usage by third parties for scoring users increasing. Upala has launched its first working prototype on the Kovan test net of Ethereum in June BrightID operates an intersectional web of trust protocol, built through graphing social connections, with the additional input of trusted seed identities. The purpose of this protocol is to allow users to provide proof that they are not using multiple accounts on a single application, and it is thus designed to be interoperable with Web 2.
The interconnectivity of its graph is designed to identify true identities and Sybil identities based on node position in relation to trusted seeds. Thus, BrightID is the solution most in line with the Intersectional Identity paradigm, formalizing social connections in order to allow for a variety of nodes to join the system and customize their own evaluation criteria.
In that sense, there are no obvious limits to the number of trusted seeds in the BrightID graph: any application utilizing their authentication solution may establish its own BrightID node with different trusted seeds. Every verification can be broadcasted to a specified isolated smart contract on Ethereum or another blockchain. The social graph serves as a common base across all nodes, but the analysis of that same graph can be distinct, so the protocol does not require consensus across nodes.
Applications may either run their nodes in a centralized or closed manner, sharing their analysis and verification outputs only with themselves, or they can provide a greater level of decentralization, allowing any user to run the verification and sample the output from a large number of nodes. To control for Sybil attacks, BrightID runs GroupSybilRank, a modification of the SybilRank algorithm, to estimate the anti-Sybil score of the network participants based on affinity between groups.
Proposed to be used as the official BrightID anti-Sybil algorithm 25 , the effectiveness of this algorithm in the presence of multiple attack vectors remains to be proved. BrightID's open Web of Trust architecture is robust and promising. That said, at this early stage, BrightID's social experiment has significant challenges to overcome in terms of Sybil-resistance, decentralization, self-sovereignty, and privacy.
As of July , its solution is limited to a small seed network, so there are no established paths for individuals or groups who are completely independent from the existing network to self-authenticate—thus, it is not yet a fully self sovereign solution. This is not an intractable limitation as new nodes can potentially define new verification methods that would allow for islands of users to be verified. However, scaling this process is far from trivial.
One possible solution is through establishing partnerships with existing social media platforms that reach a wide net of users, but this would largely defeat the aim of the initial motivators of Proof of Personhood solutions. Therefore, the crucial challenge for the success of this experiment is finding a path forward for scalability while maintaining decentralization.
To this end, BrightID's whitepaper encourages the creation of new seeding DAOs Decentralized Autonomous Organizations and establishes that the BrightID Main DAO will promote research of different seed selection methods as well as the creation of tools that can make seed selection scalable. In that sense, BrightID's success may be in tandem with an increase in the adoption of decentralized governance frameworks. Another possible pathway to scale is through BrightID's weekly pseudonym parties, during which prospective members can meet the existing community and form new links to obtain verification.
IDChain is a fork of the geth Ethereum node software, at which BrightID participants can self register via a web service to receive a lifetime supply of Eidi the native gas token on IDChain. Currently, BrightID has users with a positive anti-Sybil rank The Duniter project, originally named uCoin, was started in June Authentication within the Duniter protocol is done through a Web of Trust type of scheme. In order to become a part of Duniter's Web of Trust, one must receive five different vouches from existing members Duniter members are required to check a statement where they agree to vouch solely for new applicants who they have met in the physical world or know enough to be able to contact remotely through different channels, such as social network, forums, email, video conferences, and phone calls For each new member, a cryptographic key pair is created.
Referent members are defined by a graph property that intends to mimic the trust parameters of the real world, human, and social graphs These requirements imply that it entails significant time for new certifications to be emitted, allowing the network to manually monitor and mitigate attacks.
By doing so, the Duniter protocol delegates technical governance to human governance while still maintaining a relatively high degree of decentralization. This Web of Trust is seeing a slow but steady growth in France and nearby countries. The Equality Protocol approach creates a meta-protocol against which other identity protocols can measure their legitimacy As outlined in Figure 2 , it is designed to create an intersubjective space able to account for measurements of both collective intentionality and objective facts by combining a subjective function that provides legitimacy to the score based on Quadratic Voting and an objective function that measures the Gini Coefficient of any DAO existing on the Ethereum blockchain.
It will create a Democratic Index, as shown in the figures below, and assign a score to every Ethereum address relative to the intersection of DAOs in which it belongs as a member or its position in the social graph of blockchain-based transactions. Figure 2. Step 1: Every address that belongs to a DAO will be weighted by the Equality protocol with a percentage of the Democratic Index obtained from the intersection of DAOs that constitute the identity of such address.
Step 2: In order to counterweight false positives on the Gini Coefficient, addresses that achieve a high score will be granted the right to rank the different DAOs analyzed by the Equality Protocol oracle, according the their corresponding ability to ensure that no single Human controls more than one identifier within its domain.
Step 3: The Gini coefficient for the democracy ranges from 0 to 1, with 0 representing perfect totalitarianism and 1 representing perfect democracy. It computes a score that measure the share distribution by each segment of addresses belonging to a DAO. The current interface provides a basic personhood calculation for each DAO member of v1 Moloch DAOs, with addresses receiving a probabilistic human score Additional sources of trust can be included: different credentialing mechanisms could instantiate their protocols through a DAO, while other non-EVM protocols such as the Idena Network could be made compatible by allowing token swaps.
This approach intends only to be a meta-protocol contemplating existing DAO members rather than forming a Proof of Personhood substrate in and of itself. However, in addition to requiring that new applicants get voted in, DAOs are usually joined through the staking of resources. This system may favor capital-rich users, who could find their way into several DAOs with more ease. This is not an intractable challenge, as it is possible to earn shares through non-financial contributions, and different membership protocols could potentially make the environment more inclusive over time.
Furthermore, while the Quadratic Voting function brings a desirable governance component to identity verification, it remains to be seen whether it can serve as a rigorous substrate to signal the legitimacy of DAOs, given the inherent conflicts of interest that emerge due to the impact of results on the probabilistic score of voters. The seven reviewed projects in the digital identity space have made previously unimaginable progress in creating robust, repeatable paradigms to construct a PoP solution.
They approach the problem in a diversity of ways and use a variety of different substrates in order to successfully authenticate human users: reverse Turing tests Idena Network , social graph data emerging from a Web of Trust type of scheme Duniter, BrightID, Humanity DAO, and Kleros , and intersectional approaches that combine an analysis of objective financial value and its distribution within different domains, with some other forms of human entropy or social signaling that can be detected online Equality Protocol and Upala.
Despite the clear shortcomings present in each of these methods, their creative uses of subjectivity can point toward interesting, hybrid approaches to verify Proof of Personhood. In fact, the distinction between methods for Sybil-protection may be overdrawn: most of the solutions outlined in this review employ a combination of them in order to secure their networks. In some cases, this combination of tactics is formalized, such as with Idena Network—predicated on reverse Turing tests but accessible through their invite code system, an instance of a Web of Trust approach.
In other cases, additional protocols are appended tangentially and informally, such as BrightID's employment of weekly Pseudonym Parties to welcome new members. In this sense, the theoretical primitives have almost false separations: when it comes to implementation, they truly co-occur and build on one another rather than being contained by the distinctions we see explicated in the academy.
Below is a comparison of the different properties of PoP solutions as established in the literature. We consider each approach in light of not only its base-level attributes—governance structure, size, blockchain, protocol, and substrate—but also its performance on the primary desired properties of decentralization, privacy, and scalability. As outlined in Table 1 , each project entails significant tradeoffs, with each substrate forming or leading to a possible weakness in the system. Here we outline the research gaps evident in each protocol, with the hope of providing a path forward to addressing and solving these issues.
We begin with the Idena Network, the only fully decentralized and privacy-preserving solution. Currently, the synchronous reverse Turing test model of the network requires a significant commitment of time and effort on the part of its participants, who must participate in regular validation ceremonies approximately every 2 weeks. While its Sybil-resistance strategy is currently effective, it remains to be seen whether AI-hard tests will be able to resist the dynamic development of AI connected with neural networks and deep learning.
Furthermore, it is not certain that the current incentive model put in place will be sufficient to disincentivize the creation of a marketplace for false identities with mechanical turk attacks. Humanity DAO, while extremely promising, required the use of privately owned identity information from social networks like Twitter to verify identity, again exposing users to the vulnerabilities of Internet monopolies and largely defeating the aim of the initial motivators of such consensus identity proofs.
The system also fell prey to attack due to its necessarily fixed protocol. Kleros requires that users submit a range of personal information and video proof—effectively biometrics, which is likely to prevent many from using the service, and it remains to be seen whether their system of reward and punishment will be sufficient to prevent dishonest vouching. Upala's social responsibility concept shows promise in preserving trust but may be more accessible to capital-rich users, given that uniqueness scores are in part relative to stake—although this may be contemplated by different authentication methodologies or governance rules established by groups adopting the protocol.
Duniter's requirement of at least five vouching links and a maximum distance of five different connections from the referent members imply that it entails significant time for new certifications to be emitted. This deliberately slower rate exhibits good Sybil-protection properties but significantly restricts the network growth. The Equality Protocol, an intersubjective consensus protocol to evaluate other protocols, does not form a substrate of identity verification in and of itself, and it is currently fairly restrictive in its scope, as it solely contemplates members of decentralized autonomous organizations.
However, as discussed above, while participation rights can be earned through non-financial means, this system is particularly vulnerable to a concentration of power with capital-rich users, who can purchase the ability to join and participate in these organizations with more ease.
In addition, the use of Quadratic Voting, while clearly appropriate as a consensus mechanism, has not yet been fully substantiated as a method of signaling the legitimacy of DAOs. The key point here is around a possible conflict of interest: the protocol takes as ground truth the user rating of DAOs according to their Sybil-resistance; however, there does not yet exist a verifiable mechanism within the protocol to confirm whether this perception of Sybil-resistance from the user is true or not.
This may lead to misaligned incentives and inaccurate assessments. Finally, BrightID is currently the most intersectional solution explored in this paper and thus may have significant scalability potential. However, its current reliance on establishing trust through connections to a small, trusted seed network makes it difficult for independent groups to self-authenticate.
BrightID has a certain degree of centralization, as it relies on privately configured nodes to manage identity registries, selected by BrightID founding team, although there is promising potential for improvement with the introduction of the IDChain and integration of the seed selection and vouching process into IDChain-based DAO.
One more possible hindrance to the adoption of BrightID stands in its reliance on a public social graph, which may compromise the privacy of authenticated users if the real-world identity of some of the participants is revealed. As four out of the seven solutions analyzed in this review rely primarily on a Web of Trust, it is important to note that presently there is no evidence of the Web of Trust schemes' effectiveness for Sybil-resistance in the presence of multiple attack vectors.
Bad actors may forge multiple real relationships under different names in different groups: if there are enough non-intersecting small groups, an attacker may be able to grow a significant amount of Sybils over time. The prevention of such attacks often requires sophisticated data processing and modeling techniques: a notable example is Facebook's periodic take-down of, on average, two billion fake accounts per quarter using machine learning algorithms like SybilEdge, which employ behavioral and content classifiers to flag an account as abusive Adam, Thus, we see that there is still significant work to be done.
One possible mode of inquiry is to look to PoP systems that are not directly blockchain-based but instead use more intersectional approaches. A theoretical approach to such a project was outlined by Nicole Immorlica et al. This system would allow users to check the claims of others, with varying levels of trust, or credit, assigned to each user in relation to others; this system of credit could also extend to groups of users, as relevant, to further prevent false claims.
Such a system has been partially implemented by Identiq, which has created a providerless, peer-to-peer network that allows for companies to collaborate to validate users However, Identiq is not only itself privately-owned and closed-source, it also puts validation power in the hands of corporations and thus does not provide a fully decentralized solution, particularly one that could be leveraged for civic engagement purposes.
Protocols that focus directly on social interaction are also relevant here. Consider Nomqa 35 , an upcoming solution that verifies humanity by scoring interactions between users based on subjective meaning. This approach brings in the much-needed subjectivity component to identity solutions, considering collective, rather than purely individual, approaches to identity. However, this ambitious effort has been inactive since These seeds can then validate other identities, creating trusted clusters, which can fan out and validate larger and larger sets and communities.
Additional possible directions of future inquiry include explorations of blind research into social networks—expanding the possibilities of establishing trust between nodes while maintaining their privacy 37 as well as anticollusion systems A prominent use case for Proof of Personhood solutions is in the context of blockchain-based voting.
However, by generating a record of transactions, blockchains can facilitate bribery, with smart contracts created to reward users if they are able to demonstrate a certain voting pattern through a publicly verifiable transaction Daian et al. Minimal Anti-collusion Infrastructure is a scheme, currently employed by BrightID 39 , that aims to address these types of attacks by allowing voters to switch their voting keys at any time: thus, one may provide a voting receipt but can never guarantee that said vote had not been formerly invalidated by a key switch.
While there are still possible vectors of attack one could sell their private key , the Minimal Anti-collusion Infrastructure outlines a promising approach to address on-chain privacy for identities being used in voting mechanisms. Any endeavor to create functioning digital democracies can be undermined by exploitation of identity, from the automated creation of false identities to corruption by third parties controlling a voter registry.
Determining who has the right to participate cannot be an afterthought of democracy: it is its elemental task. However, it must also be noted that democratic governance is possible even with bounded Sybil penetration, meaning that a small amount of error within a system can be forgiven, which opens up possibilities for more intersectional and subjective approaches Shahaf et al.
Finally, the steady advancement of machine learning and artificial intelligence makes the question of formalizing identity frameworks particularly urgent. Trustworthy and high-quality information is the foundation of a functioning democracy—and yet from deep fakes to language model outputs, machine-generated information is becoming easier to generate and spread.
In the future, there may be a need for cryptographic signatures on selected media or information pieces to establish trust and authenticity Ford, Thus, in many senses, governance, democracy, and identity are strictly correlated. Structuring communication architectures anchored on decentralized, privacy-preserving, self-sovereign, and Sybil-resistant identity protocols that can reach all humans with an Internet connection can open the path for new, radically participative peer-to-peer political movements and economies.
Identity is one of our most fundamental human attributes. However, in the age of surveillance capitalism, identity itself has become a part of a new, digital political frontier 41 Zuboff, Consolidated credential mechanisms today all verify humans by implementing practices that require the disclosure of personal and private information to an identifier.
Eventually, this wealth of information accrues into credential monopolies, which are a prominent force in the perilous drift toward democratic deconsolidation now threatening Western democracies. While there is significant space for action in advancing effective public policies that contemplate those threats, approving and enforcing them is often extremely challenging in the face of the powerful market forces they stand against.
In that sense, the alternative technological paradigms that may arise from Proof of Personhood systems could provide a relevant path toward guaranteeing privacy and participation rights. Furthermore, surveillance capitalism bears a worldview that downgrades human value and dignity in favor of machine learning systems. Proof of Personhood systems counter that logic by creating the building blocks of a human-centered economy, where individuals directly control and have governance rights over the networks, communities, and organizations they belong to.
These systems invert the current logic of capitalism, creating the base for solidarity economies that can safeguard and elevate the role of human consciousness, choice, and agency. Yes, the approaches explored in this review fall short of this goal in several ways, some still relying on existing sources of centralized information, others on small networks or high-friction synchronous tasks.
Nonetheless, Proof of Personhood projects present one of the few viable alternatives capable of addressing these problems at their root. In doing so, they illustrate that the best technologies do not abstract away subjectivity. Instead they embrace it, seeing subjectivity for what it is: not just a necessity, but a strength. PB and DS have co-written and contributed to the manuscript in its entirety. SI has primarily contributed to the Proof of Personhood section and the analysis of the decentralization, privacy, and scalability aspects of each protocol while also reviewing the manuscript in its entirety.
SS has primarily contributed to the Introduction and Conclusion sections while also making significant contributions to the analysis of protocols and reviewing the manuscript in its entirety. All authors contributed to the article and approved the submitted version.
Kleros has a cryptocurrency associated with its protocol, the PNK, currently available in the market, although PB and SS have not been compensated in PNK or any other form for their minimal contributions.
The Idena Network has a cryptocurrency associated with its protocol currently available in the market, the DNA, while Democracy Earth Foundation may have a cryptocurrency available in the market in an unknown future. Both Idena Network's and Democracy Earth's cryptocurrencies are designed to be granted to all unique and verified members of their respective networks, at no cost other than those associated with authenticating Proof of Personhood.
Decentralized Identity Trilemma. Smart Contracts [Website]. Ethereum Whitepaper [Blog Post]. How Idena Works [Blog]. Epoch BrightID Anti-Sybil. Hybrid approaches to Sybil prevention, incorporating each of three key elements, are common to address concerns. The first way to mitigate a Sybil attack is to raise the cost of creating a new identity. Since identities can map to entities on a many to one ratio, we need a way to make it resource intensive to create too many identities.
The challenge here, though, is there are many legitimate reasons why you might want to operate multiple identities. Redundancy, resource sharing, reliability, and anonymity are all good reasons to create multiple identities on a peer network. Instead, it should be just enough to make it unfeasible to create many identities in a short period of time.
Blockchains use the cost of creation as a Sybil protection feature through mining. This attaches a significant cost to adding hundreds or thousands of pseudonymous nodes that might be able to influence the adoption of a fork or other blockchain vote.
The same goes for proof of stake, where purchasing computing power is replaced by staking currency. That resource requirement limits the number of accounts a bad actor can create. A second way to fight Sybil attacks is requiring some type of trust before allowing a new identity to join the network. This usually takes the form of a reputation system, where only established, long-term users can invite or vouch for new entrants to the network. Other variations rely on a probationary system where new accounts are possible but they must remain active and unique for a certain period before they receive voting privileges.
Two-factor authentication is one tactic for Sybil prevention. Chain of trust also extends to outright identity verification. Some peer networks require you to submit identification before joining. Others allow you to join if you can answer a two-factor authenticated security code.
Still others restrict account creation based on IP address. All of these require some level of identity verification or trust building before an account receives voting privileges, making the creation of pseudonyms more challenging. The final way to mitigate the threat of Sybil attacks is by weighting user power based on reputation. Users that have been around the longest and proven themselves receive more voting power on communal decisions. This makes the system a meritocracy instead of a pure democracy, and it lowers the power of new users.
Sybil attacks involve false identities and hidden motives. Still, networks that implement a combination of these prevention measures see increased protection from Sybil attacks, mitigating the potential severity of the attack if and when it comes. Blockchain domain registry sites are changing how we register, manage and resolve domain names on the blockchain.
Each blockchain DNS domain name system is decentralized; it runs on a peer-to-peer server system without the need for a middleman or central governing body.
|Cryptocurrency lingo||Decentralization is not considered; the specifications of validators are accessible to anyone and the threat of harming the reputation does not really shield a person from taking part in pernicious activities. Difficulty, minBlockHeight, minDeposit, depositAddress. The implementations are evaluated using common IoT hardware, i. Author sybil attack ethereum Article notes Copyright and License information Disclaimer. SybilGuard [ 23 ] is a well-known protocol that limits the harmful influence of Sybil attacks in P2P networks. The Overflow Blog. Viewed 1k times.|
|Emerald wallet crypto||The top 5 cryptocurrencies|
|Trade cryptocurrency free||Ethereum will fall below 10p|
|Ethereum co founder time bomb||Info on bitcoin|
|Facebook is planning to launch its own cryptocurrency||Examples of such prevention techniques include SybilGuard SybilLimit ethereum Advogato Trust Metric SybilRank and the sparsity based metric to identify Sybil clusters in a distributed P2P based reputation system. We also plan to evaluate further Sybil attack use-cases for Rechained in the real world. The identity proof and private key priv are flashed or otherwise transferred to the device that uses the generated identity step 5. Typically, the kind of substrate provided needs to be easy for humans to produce, but difficult for Artificial Intelligence to replicate, thus diminishing the ability of computer-generated false identities to take over the protocol. Address, Balance.|
|Crypto currency hlod||Elvn crypto|
|Ethereum mining rig hashrate||Ice3x ethereum|
|Why is bitcoin litecoin ethereum crashing||304|
|Xem cryptocurrency price||Figure 1 illustrates the general structure of a blockchain, as used by, e. PoA provided increases the speed transaction validation and works as a platform for the development and maintenance of DApps. The Equality Protocol approach creates a meta-protocol against which other identity protocols can measure their legitimacy As an additional layer of security, Idena requires new members to present an invite code to be able to join their first authentication ceremony. Kleros requires that users submit a range of personal information and video proof—effectively sybil attack ethereum, which is likely to prevent many from using the service, and it remains to be seen whether ethereum mining low payout system of reward and punishment will be sufficient to prevent dishonest vouching. Therefore, an anti-Sybil identity system is a requirement for their application within the context of open, peer-to-peer networks Lalley and Glen, ; Buterin et al.|
No mechanism to assure the assumption is specified, however. Thus, it's a validator responsibility. It's highly probable that many validators will use NTP to synchonize their clocks to the world standard i. UTC , since it's an easy to set up and alternatives can be expensive. An excerpt from the NTP pool page :.
The pool is being used by hundreds of millions of systems around the world. It's the default "time server" for most of the major Linux distributions and many networked appliances. Or they can users servers from other public NTP server lists, e. Because of the large number of users we are in need of more servers. If you have a server with a static IP address always available on the internet, please consider adding it to the system.
Such situation creates an opportunity for a Sybil attack on the beacon chain protocol, under certain conditions. NTP protocol can tolerate certain errors, e. However, in case there are many faulty NTP servers in the pool, there is a high probability that a correct server will look as a "falseticker".
NTP pool servers are also monitored by the pool software. However, if the adversary knows IP addresses of beacon chain protocol participants, its faulty NTP servers can report wrong time results only to clients which IP addresses in the list. This is why the NTP servers controlled by the adversary are considered as Byzantine-faulty two-faced clocks.
If few validators' clocks are distorted by such an attack then beacon chain protocol can tolerate it. However, the key problem with the scenario is that many validators can be vulnerable to the attack, if they are not careful enough when setting NTP up. So, multiple correlated faults can be induced alone or together with other means to attack the beacon chain protocol. Note, that as non-validator nodes can participate in the p2p graph, then they can be used to attack the beacon chain protocol too.
The attack is described in more details in a separate document. It's relatively easy to withstand the attack, e. Using NTP servers controlled by big corporations, non-profit or government agencies can be a possibility, however, it can lead to a similar correlated implicit dependency and lack of decentralization. Which maybe not desirable for various reasons.
Wealthy validators can set up their own time servers, however it increases significantly an entry barrier to run a validator node. The main goal of the issues is to warn Ethereum 2. Thus, it's a risk to the overall beacon chain protocol. These minimal counter-measures are hardly enough, so the best solution would be to design BFT clock synchronization protocol, so that validator and non-validator node adminstrators are relieved from the secure Time Service setup burden.
However, such BFT protocol can be prohibitively expensive given expected beacon chain protocol scale thousands of nodes , so a cheaper solutions are to be investigated too. We stress out that beacon chain protocol can tolerate limited number of validators with vulnerable NTP setups, so probably a separate BFT clock synchronization protocol can be excessive, if there exists a way to prevent correlated NTP-level failures.
The text was updated successfully, but these errors were encountered:. Has someone detailed what the actual attacks are that you can do if you control the time of any arbitrary number of nodes? Presumably they would concern liveness but not safety? This is actually implemented in the standard ntpd as the "panic" flag and set to s by default -- by advising validators to set it to a much smaller value, could we mitigate this attack or at least force the attacker to introduce their skew "slowly" which would make it potentially detectable long before the attack can be executed?
Sorry, something went wrong. Severe clock disparity - around epoch duration sec can lead to liveness violation, i. Safety in theory can be compromised too, due to 'inactivity leak', i. I analyzed it in more details in the document. Vitalik Buterin also discussed it earlier in his post. Given that they now control the entire wallet, they can trivially extract the remainder of the balance. So what was ultimately the vulnerability? You could argue there were two.
First, the initWallet and initMultiowned in the wallet library were not marked as internal this is like a private method, which would prevent this delegated call , and those methods did not check that the wallet wasn't already initialized. Either check would've made this hack impossible. The second vulnerability was the raw delegateCall. You can think of this as equivalent to a raw eval statement, running on a user-supplied string. In an attempt to be succinct, this contract used metaprogramming to proxy potential method calls to an underlying library.
The safer approach here would be to whitelist specific methods that the user is allowed to call. The trouble, of course, is that this is more expensive in gas costs since it has to evaluate more conditionals. But when it comes to security, we probably have to get over this concern when writing smart contracts that move massive amounts of money. It was a clever catch, but once you point it out, it seems almost elementary. The attacker then jumped on this vulnerability for three of the largest wallets they could find — but judging from the transaction times, they were doing this entirely manually.
The DAO hack was unique in that when the attacker drained the DAO into a child DAO, the funds were frozen for many days inside a smart contract before they could be released to the attacker. This prevented any of the stolen funds from going into circulation, so the stolen Ether was effectively siloed. This gave the Ethereum community plenty of time to conduct a public quorum about how to deal with the attack. In this attack, the attacker immediately stole the funds and could start spending them.
A hard fork would be impractical—what do you do about all of the transactions that occur downstream? What about the people who innocently traded assets with the attacker? First, remember, this was not a flaw in Ethereum or in smart contracts in general. Rather, it was a developer error in a particular contract. The developers here were a cross-collaboration between the Ethereum foundation literally the creators of Ethereum , the Parity core team, and members of the open-source community.
It underwent extensive peer review. This is basically the highest standard of programming that exists in the Ethereum ecosystem. These developers were human. They made a mistake. And so did the reviewers who audited this code. How was it even possible they missed this?
When I see responses like this, I know the people commenting are not professional developers. For a serious developer, the reaction is instead: damn, that was a dumb mistake. Mistakes of this sort are routinely made in programming. All programs carry the risk of developer error. As programs scale to non-trivial complexity, you have to start taking it as a given that programs are probably not correct.
No amount of human diligence or testing is sufficient to prevent all possible bugs. Even organizations like Google or NASA make programming mistakes, despite the extreme rigor they apply to their most critical code. We would do well to take a page from site reliability practices at companies like Google and Airbnb. In these postmortems, there is always a principle of never blaming individuals.
Blaming mistakes on individuals is pointless, because all programmers, no matter how experienced, have a nonzero likelihood of making a mistake. Instead, the purpose of a postmortem is to identify what in the process allowed that mistake to get deployed.
The problem was not that the developer forgot to add internal to the wallet library, or that they did a raw delegateCall without checking what method was being called. The problem is that their programming toolchain allowed them to make these mistakes. As the smart contract ecosystem evolves, it has to evolve in the direction of making these mistakes harder, and that means making contracts secure by default.
Strength is a weakness when it comes to programming languages. The stronger and more expressive a programming language is, the more complex its code becomes. Solidity is a very complex language, modeled to resemble Java. Complexity is the enemy of security. Complex programs are more difficult to reason about and harder to identify edge cases for. I think that languages like Viper maintained by Vitalik Buterin are a promising step in this direction.
The less the language lets you do, the easier it is to analyze and prove properties of a contract. The fewer possible attack vectors you have to consider, the easier it is to develop a secure contract. A simpler programming model also allows things like formal verification and automatic test generation. These are areas under active research, but just as smart contracts have incorporated cutting-edge cryptography, they also should start incorporating the leading edge of programming language design.
Most of the programmers who are getting into this space, myself included, come from a web development background, and the blockchain toolchain is designed to be familiar for web developers. Solidity has achieved tremendous adoption in the developer community because of its familiarity to other forms of programming.
In a way, this may end up being its downfall. The problem is, blockchain programming is fundamentally different from web development. Before the age of the client-server web model, most programming was done for packaged consumer software or on embedded systems. This was before the day of automatic software updates. In these programs, a shipped product was final — you released one form of your software every 6 months, and if there was a bug, that bug would have to stand until the next release.
Because of this longer development cycle, all software releases were rigorously tested under all conceivable circumstances. Web development is far more forgiving. These two development models are fundamentally different. Most programmers today are trained on the web development model. Unfortunately, the blockchain security model is more akin to the older model.
In blockchain, code is intrinsically unrevertible. Being on Ethereum by definition means everyone owns your server. And once your attack is successful, you can potentially steal all of the money in the contract. Imagine that you were deploying software for vending machines.
But instead of a bug allowing you to simply steal candy from one machine, the bug allowed you to simultaneously steal candy from every machine in the world that employed this software. In the case of a successful attack, defense is extremely difficult. The white-hats in the Parity hack demonstrated how limited their defense options were — there was no way to secure or dismantle the contracts, or even to hack back the stolen money; all they could do was hack the remaining vulnerable contracts before the attacker did.
Rather, it confirms what everyone already knows: this ecosystem is young and immature. This means not just programmers maturing and getting more training. It also means developing tools and languages that make all of this easier, and give us rigorous guarantees about our code. You should not treat Ethereum as a bank or as a replacement for financial infrastructure. But despite all that, I still think Ethereum is going to win in the long run. Ethereum will not live or die because of the money in it.
It will live or die based on the developers who are fighting for it. They did it because they believe in this ecosystem. They want Ethereum to thrive. They want to see their vision of the future come true. They are fundamentally why Ethereum will win in the long run—or if they abandon Ethereum, their abandonment will be why it loses. This attack is important. It will shake people up. It will force the community to take a long, hard look at security best practices.
It will force developers to treat smart contract programming with far more rigor than they currently do. In the end, attacks like this are good for the community to grow up.
A Sybil Attack is a vulnerability that affects the blockchain and that consists of an attacker controlling various nodes of the network in. In a Sybil attack, malicious nodes participate in a network not only Subsequently, Section presents an Ethereum- and Bitcoin-based. A Sybil attack is an attempt to control a peer network by creating multiple fake identities. To outside observers, these fake identities.