Unstoppable Domains

Name-Service Concept: The Unstoppable Domains system is a service that operates on top of the Polygon blockchain platform. Although a naming service, it is intended primarily not to map names to computers but instead names to data references such as cryptocurrency wallet addresses, although it does support DNS type records or IPFS (Inter-Planetary File System) identifiers. Conceptually there are a set of primary domains (currently .crypto, .nft, .x, .wallet, .polygon, .dao, .888, .zil, .blockchain, and .bitcoin) that Unstoppable Domains supports, and although name transfers and management occur through the Polygon smart contracts, almost all interactions are through Unstoppable Domain’s centrally managed and controlled API.

Polygon’s Computational Model: Polygon supports Ethereum’s virtual machine, albeit with different gas parameters and costs. Ethereum, unlike previous cryptocurrencies, implements a deterministic virtual machine that executes programs that are stored in Ethereum’s public ledger when transacting in the cryptocurrency. Reading the ledger has no cost, but executing a transaction and the associated program is charged ‘gas’ for each instruction executed by the virtual machine. Polygon inherits the computational model from Ethereum.

The model of computation requires that someone who wishes to make a transaction needs to provide a gas fee calculated as the number of units times the cost-per-unit. If the computation completes the user is charged for the amount of gas used but if the computation fails to terminate before the gas is exhausted all the gas fees are forfeited.

The gas fee is split into two parts, a fixed amount that is “burned” (removed from circulation) and a variable amount that goes to the validator which wins the cryptocurrency lottery and successfully creates the block, creating an auction dynamic where a user can bid higher in attempt to get their transaction included sooner under circumstances of high demand.

The fixed portion of the gas fee itself dynamically responds to demand. Each Polygon block (created roughly every 2 seconds) can contain transactions consuming at most 20 million units of gas. But if the amount of gas used is over 10 million, the base portion of the per-gas transaction fee grows exponentially until the Polygon blocks are reduced to using only 10 million gas.

Fortunately for those using the Polygon blockchain the gas cost itself is moderately reasonable as Polygon itself is not very valuable: 100,000 gas costs a bit over $.01 (it is actually $.03 at the time of writing, but we will assume $.01 just to keep the back of the envelope math easier). However, the exponentially increasing cost can regularly spike prices by 2x or more in the space of a minute.

As a computational fabric Polygon is not very significant. A single 256b add operation consumes 3 gas, so the 5 million gas/second can, at most, compute 1,700,000 256b adds per second yet costs over $.50 a second to use. In comparison a <$75 Raspberry Pi 4, with its 1.5 GHz quad core superscalar ARM processor, can implement a 256b addition using 4, 64b adds and thus has a theoretical maximum performance of 3 billion 256b adds/second: 4 orders of magnitude more powerful for just the cost of less than 3 minutes of computation on the Polygon blockchain.

Likewise storage is similarly expensive and is implemented as a key/value store using 256b keys and 256b data blocks. Storing a 256b block of data at a 256b key into the Polygon ledger uses a complex formula, but in the end writing a block of data to a new key requires slightly more than 20,000 gas while changing an existing key requires 5000 gas. Thus storing a new KB of data into the Polygon ledger requires storing 640,000 gas, or roughly $0.06 while updating this KB of data will cost a little more than a penny. Again, these represent normal costs but high demand can cause an exponential increase in the transaction fees.

But although small per KB, these costs quickly grow well beyond conventional solutions. Storing 1 GB of data in Polygon costs at least $60,000. In comparison, an Amazon S3 bucket charges $.023 per gigabyte-month, with data transfer costing $.09 per GB transferred out of Amazon. So assuming the GB of data is also downloaded 1000 times a month, the cost of storing 1 GB of data in Polygon is equivalent to 50 years of Amazon service. If the data is not used outside of Amazon (thus not incurring download charges) this 1 GB of data on Polygon is equivalent to over 10 millenia of Amazon storage.

In building Polygon applications it is thus critical to limit the amount of gas used whenever possible, as any update to Polygon’s global state is significantly expensive which means although the Polygon “smart contracts” represent general-purpose programs, it can be a substantial cost to perform any actual computations in this fabric.

In contrast, reading the global state is free from the outside since it is a single global ledger of data. So although reading the data is also a program, the read operations can be invoked without executing data into the global ledger and its associated costs.

Finally, although the Polygon blockchain claims to be “decentralized”, almost all Polygon applications (called Dapps or Web3 apps) rely heavily on centralized and trusted intermediaries. Simply reading the Polygon blockchain to extract relevant information requires maintaining a 1.2 TB pool of data and needs to be updated continuously to avoid going out of sync. As such almost no Polygon application relies on directly reading this data.

Instead, Polygon applications use third party services provided by centralized providers like Infura. This includes browser extensions like MetaMask that are used to mediate interactions between a user’s cryptocurrency wallet and Polygon applications. Although in theory users can use alternate data providers, in practice users tend to use the default providers when deploying and interacting with blockchain applications.

Development History and Organizational Model: Unstoppable Domains is a commercial entity with backing from multiple venture capital firms, and maintains a tight control over the development process. Although clearly inspired by the Ethereum Name System (ENS) in terms of structure the actual implementation is independent, and Unstoppable Domains as a company is largely focused on streamlining the process: Names are registered using credit cards or other conventional payments and they offer hosting services that eliminate the need for a user to deal directly with the underlying cryptocurrencies. Major venture firms have invested roughly $65M with a notional valuation of $1B.

Namehash: Overall, Ethereum and Ethereum-derived systems have poor support for strings. The storage model for persistent data is just 256b key/256b value pairs. Thus the initial core transformation necessary is a Keccak-256-based hashing for names. After normalizing to lower case and punycode as performed by DNS, ENS’s namehash, which Unstoppable Domains adopts is a recursive structure consisting of the hash of the current set as the hash of the upper level concatenated with the current label and then hashed, with the hash of the empty string defined as 256 bits of 0s.

So, for example, the hash of an.unstoppable.crypto is calculated as H(H(H(0x0.. || crypto) || unstoppable ) || an). This scheme results in a deterministic, hierarchical hash so a name will have not only a consistent hash for the label itself but a series of higher level hashes that can enforce a hierarchy.

Name registration: Initial name registration is handled entirely through Unstoppable Domains and their web interface. The underlying contracts used for data storage (primarily on Polygon, but also supporting names stored on Ethereum and Zilliqa) can only be initialized by Unstoppable Domains, forcing all users to register through Unstoppable Domains’s web site and pay to register by directly paying Unstoppable Domains.

The cost that Unstoppable Domains charges is a one-time fee that depends on the cost of the domain, so for example they currently request $1000 to register primates.crypto, but only $40 to register aonecufasonefu.crypto. At that point a user can have the new domain’s control transferred to their cryptocurrency address, or have Unstoppable Domains manage operation for a fee.

Once a user has control over the domain they can then add key/value pairs to the domain, or if managed by Unstoppable Domains, use the web interface to have Unstoppable Domains register it. For individual users Unstoppable Domains charges $99/year for managing unlimited domains, and in the process will pay the gas fees on data update, but if the user self-hosts they will need to pay the gas fees necessary, currently a couple of pennies for any data update.

Keys are primarily intended to represent cryptocurrency addresses, but it can also support DNS data and IPFS (Inter-Planetary-File-System) record locators, allowing web sites to be “hosted” using Unstoppable Domains names.

The gas limit in Polygon also imposes a global limit on the update rate. If Unstoppable Domains executed approximately 90 updates per second it would exhaust the capacity of the polygon blockchain.

Name transfer: Like ENS, Unstoppable Domains implements control over a domain as an ERC-721 token (aka a ‘non-fungible token’). The control of the token controls the rights to update the associated data with a name and can be transferred or sold to others either directly or on third party markets like OpenSea. The smart contract itself does not enforce an additional transaction fee beyond the underlying “gas fee” necessary to transfer a name.

Name resolution: Although in theory a name resolution system could directly access the data on the various blockchains (Unstoppable Domains will register across three different blockchains: Ethereum, Polygon (MATIC), and Zilliqa (ZIL)), resolution is performed almost entirely through a RESTful API operated by Unstoppable Domains, allowing a single query to obtain the record set associated with the name.

The Opera and Brave web browsers use this API to process requests in the .crypto domain, and browser extensions are available for Firefox and Chrome to support other domains.

The .coin domain: Unstoppable Domains initially included .coin as a top level domain that customers could use. However, another blockchain naming scheme, Emercoin, had previously started using .coin as a top level domain. After becoming aware of the conflict, Unstoppable Domains decided to withdraw .coin from the names they register and offer a refund in store-credit to those who had registered names in that top level domain. This was primarily as a way of establishing a ‘first come, first served’ precedent in the blockchain namespace domains.

Unstoppable Domain’s withdrawal of .coin wasn’t limited to just a refund, however. Although customers who did not seek a refund would still “own” .coin domains on the Polygon blockchain, Unstoppable Domains announced that their resolving APIs would no longer support .coin, meaning that as a central authority Unstoppable Domains was able to stop all use of .coin “Unstoppable” Domain”.

Lawsuits: Unstoppable Domains strongly believes in attempting to apply trademark protection to their top level domains. The Handshake naming system supports arbitrary top level domains, and a user registered .wallet as a top level domain in Handshake and began selling names underneath it. Unstoppable Domains sued, arguing trademark infringement and other claims. Currently the various cases are working through the court system.

Dispute Resolution: There exists no dispute mechanism within Unstoppable Domains, but there is potential to implement a dispute resolution service in practice as discussed in the security section. The lack of dispute resolution is argued as a feature by the developers (names are “unstoppable”), but this means that there can be no method to remove problematic domains, resolve trademark disputes, nor even recover from cryptographic errors.

The ownership of domains themselves can also be pseudonymous, only referred to by cryptocurrency address. For names controlled by Unstoppable Domain’s they would maintain ownership records but such records disappear when a name is transferred to a third party. This means it can be difficult or impossible to discover the actual identity of an owner of a problematic domain.

Security: As long as the domain owner maintains control of their private key the internal name system data security is effectively equivalent to modern DNSSEC. But unlike DNSSEC there are cryptographic failures that can render an “Unstoppable Domain” permanently unrecoverable.

Unstoppable Domain users are vulnerable to catastrophic system compromise like almost every other cryptocurrency. An attacker who gains a target’s private key can both remove all cryptocurrency assets and can transfer any “Unstoppable Domain” names to the attacker, permanently stealing from the target the ability to control or update the name. Similarly, if a domain owner loses their private key there is no way to update the information stored in the registrar.

Unstoppable Domains understands the problems with this model. As such they also explicitly offer custodial services for a fee where Unstoppable Domains, not the user, actually controls the cryptographic keys. This can allow recovery in the case of lost access but there is no indication that Unstoppable Domains will limit the ability to transfer out in the event of a compromise.

The resolution process, however, is completely dependent on Unstoppable Domains and there is no cryptographic integrity in the JSON API, so even if a name is “owned” by a wallet entirely outside of Unstoppable Domain’s control, Unstoppable Domains in practice has complete control over what data is actually returned to a client in response to a request, allowing it to both censor and modify values at will.

This control was clearly executed in the case of the .coin domain. Although the names remained in control of the “owners”, the ability to resolve the names was removed by Unstoppable Domains with a single change to their API.

Unstoppable Domains does not currently offer any sort of dispute resolution service, which leaves both compromises and errors unrecoverable (except in the case where a lost password for accessing a name in Unstoppable Domain’s custody), but their position in the resolution process would enable them to implement a dispute service. However, resolving disputes would make it plain that “Unstoppable” Domains are anything but, and the “uncensorable” blockchain data is not the final source of truth in the system.

Data Privacy: Due to Polygon and other chains acting as a global public ledger, all the domains are public in namehash form, allowing any human-recognizable domain to be effectively brute-forced to be identified. All data associated with the domain itself is public and with no obfuscation. For subdomains (e.g. an.example.crypto) it is recorded by namehash so if the name is predictable both the name and associated data can be known but if the name is unpredictable only the data fields are public.

Reading this data outside of a smart contract is private except to Unstoppable Domains’s API service provider, while reading the data within a smart contract is public as the entire stream of execution of a smart contract is a public activity.

Record Enumeration: As Unstoppable Domains themselves are the only one issuing calls to the smart contract that registers names, this registration can be performed by namehash. Thus only human-readable names can be externally enumerated by using a brute-force hashing method similar to NSEC3 enumeration.

Data Update Mechanism: A transaction to update data in the public registrar costs roughly 40000 to 100000 gas, depending on the type of update (cryptocurrency keys or larger text records). If the only use of Polygon was Unstoppable Domains this would support a global update rate of roughly 45 to 90 names/second before the cost per transaction grows exponentially.

Unstoppable Domains is just one use of the Polygon blockchain. The Polygon blockchain regularly experiences fee spirals where the cost per transaction can double in moments. For users operating through Unstoppable Domains’s custody service this isn’t a problem as Unstoppable Domains pays the gas fees and Polygon is currently inexpensive to use but it does impose a global update limit. However, if gas fees on Polygon ever approach those of Ethereum, Unstoppable Domains would probably increase their hosting prices substantially to pass on these costs to the customers.

Integration Into Existing DNS: There is currently no suggestion that Unstoppable Domains wishes to add a DNS gateway to their API, either under their own domain names (e.g. crypto.unstoppabledomains.com) or by registering as a new DNS Top Level Domain (TLD) registrar. Implementing a DNS gateway under an existing domain would be straightforward technically and legally, but it would make it clear that the “Unstoppable Domains” namespace is separate from the DNS namespace.

Unstoppable Domains could theoretically register as a provider for new DNS TLDs, but there are several complications. The names Unstoppable Domains uses (especially .crypto, .nft, and .888) would be highly coveted TLDs for competitors or others and for Unstoppable Domains to represent DNS names they would need to control all TLDs they currently implement.

But even assuming Unstoppable Domains could register as a TLD provider it would probably be incompatible with their business model. The very premise, that domains are “unstoppable”, runs counter to the legal requirements that a TLD needs to meet in the DNS system. A registrar for a TLD needs to provide a dispute resolution service, blocking or removing names subject to various legal actions. Acting as a TLD registrar would mean Unstoppable Domains couldn’t be “unstoppable”.

Overall Suitability: Unstoppable Domains has several limitations that may prove problematic if it seeks to act as a significant TLD. There exists no dispute resolution service to moderate disputes or recover from errors such as lost or stolen cryptographic keys. Adding such a dispute resolution service runs counter to the “unstoppable” narrative, and would require that Unstoppable Domains implement a control layer in the APIs that are used to actress the data. Unstoppable Domains appears to have no interest in integrating into existing DNS. The Polygon data storage layer also has problems. Like all “blockchain” systems it actually relies on centralized providers to read data and has a limited update bandwidth. Under current conditions the Unstoppable Domains system is limited to a global rate of roughly 90 data updates per second, assuming no other uses for the Polygon blockchain.