This document lists frequently-asked questions and answers to technical questions about Blockstack.
If you are new to Blockstack, you should read the non-technical FAQ first.
If you have a technical question that gets frequently asked on the forum or Slack, feel free to send a pull-request with the question and answer.
Blockstack is a new Internet for decentralized applications. Blockstack applications differ from Web applications in two ways:
- Users own their identities. The user brings their identity to the applications; applications do not require the user to create accounts and passwords.
- Users own their data. Users control who can read it, and where it gets stored. The application does not need to worry about hosting any user data.
The Blockstack project provides all of the infrastructure required for building these kinds of applications.
Yes! The components that make up Blockstack do not have any central points of control.
- The Blockstack Naming Service runs on top of the Bitcoin blockchain, which itself is decentralized. It binds Blockstack IDs to a small amount of on-chain data (usually a hash of off-chain data).
- The Atlas Peer Network stores chunks of data referenced by names in BNS. It operates under similar design principles to BitTorrent, and has no single points of failure. The network is self-healing---if a node crashes, it quickly recovers all of its state from its peers.
- The Gaia storage system lets users choose where their application data gets hosted. Gaia reduces all storage systems---from cloud storage to peer-to-peer networks---to dumb, interchangeable hard drives. Users have maximum flexibility and control over their data in a way that is transparent to app developers.
Yes! Blockstack applications are as easy to use as normal Web applications, if not easier. Moreover, they are just as performant if not more so.
If you install the Blockstack Browser, or use our Web-hosted Blockstack Browser, you can get started with them right away.
Your user account is ultimately controlled by a private key. You and only you know what the private key is, and using your private key, you can prove to other people that you own a particular piece of data (such as your Blockstack ID).
Your private key resides within your locally-running Blockstack Browser. It never leaves your computer.
Your public keys are stored off-chain, and the hash of your public key is stored on the Bitcoin blockchain. The Blockstack Naming Service allows anyone to look up your public key hash, given your Blockstack ID.
As a Blockstack user, you can choose exactly where your data gets stored. Blockstack uses a decentralized storage system called Gaia to host your data. Gaia is different from other storage systems because it lets you securely host your data wherever you want---in cloud storage providers, on your personal server, or in another decentralized storage system like BitTorrent or IPFS.
When you register, you are given a default Gaia hub that replicates your data to a bucket in Microsoft Azure. However, you can configure and deploy your own Gaia hub and have Blockstack store your data there instead.
The Blockstack Naming Service and the Atlas network work together to help other users discover your app-specific public data, given your Blockstack ID.
Blockstack IDs are usernames. Unlike normal Web app usernames, Blockstack IDs are usable across every Blockstack app. They fill a similar role to centralized single-signon services like Facebook or Google. However, you and only you control your Blockstack ID, and no one can track your logins.
If you install the Blockstack Browser or use the Web-hosted Blockstack Browser, you can purchase one with Bitcoin.
No, you can use Blockstack applications right away. However, if you want to share data with other users, then you need a Blockstack ID.
Blockstack IDs are used to discover where you are keeping your
(publicly-readable) application data. For example, if alice.id wants to share
a document with bob.id, then bob.id's browser uses the Blockstack ID
alice.id to look up where alice.id stored it.
The technical descriptions of how and why this works are quite long. Please see the Blockstack Naming Service documentation for a full description.
This is also a Blockstack ID, and can be used for all the things a Blockstack ID
can be used for. The only difference is that they have the format foo.bar.baz
instead of bar.baz. For example,
jude.personal.id is a
Blockstack ID, and is a subdomain of personal.id.
Subdomains are first-class Blockstack IDs---they can be used for all the same things that an on-chain Blockstack ID can be used for, and they have all of the same safety properties. They are globally unique, they are strongly owned by a private key, and they are human-readable.
Subdomains are considerably cheaper than Blockstack IDs, since hundreds of them can be registered with a single transaction. The BNS documentation describes them in detail.
Subdomains provide a fast, inexpensive way to onboard many users at once.
Blockstack subdomains can be obtained without spending Bitcoin by asking a subdomain registrar to create one for you.
Yes! It's at https://explorer.blockstack.org
Yes! Blockstack is geared primarily towards Web developers. All of your existing knowledge is immediately applicable to Blockstack. Anything you can do in a Web browser, you can do in a Blockstack app.
Yes! Blockstack implements a RESTful API which lets you interact with Blockstack from any language and any runtime. In fact, the reference client (blockstack.js) is mainly a wrapper around these RESTful API calls, so you won't be missing much by using a language other than Javascript.
Blockstack apps are built like single-page Web apps---they are, in fact, a type of Web application.
Blockstack apps are a subset of Web applications that use Blockstack's technology to preserve the user's control over their identities and data. As such, they tend to be simpler in design and operation, since in many cases they don't have to host anything besides the application's assets.
No. Blockstack applications are built using existing Web frameworks and programming The only new thing you need to learn is either blockstack.js or the Blockstack RESTful API.
The blockstack.js library gives any Web application the ability to interact with Blockstack's authentication and storage services. In addition, we supply a public RESTful API.
This is the reference client implementation for Blockstack. You use it in your Web app to do the following:
- Authenticate users
- Load and store user data
- Read other users' public data
Please see the API documentation here.
You can use blockstack.js, or you can use the public Blockstack Core
endpoint.
The URLs to a user's public app data are in a canonical location in their
profile. For example, here's how you would get public data from the
Publik app, stored under the Blockstack ID ryan.id.
- Get the bucket URL
$ BUCKET_URL="$(curl -sL https://core.blockstack.org/v1/users/ryan.id | jq -r '."ryan.id"["profile"]["apps"]["http://publik.ykliao.com"]')"
$ echo "$BUCKET_URL"
https://gaia.blockstack.org/hub/1FrZTGQ8DM9TMPfGXtXMUvt2NNebLiSzad/- Get the data
$ curl -sL "${BUCKET_URL%%/}/statuses.json"
[{"id":0,"text":"Hello, Blockstack!","created_at":1515786983492}]You should use the Blockstack Browser.
You can deploy and use a Blockstack Subdomain Registrar, or use an existing one.
Blockstack applications do not currently have have access to the user's wallet. Users are expected to register Blockstack IDs themselves.
However, if you feel particularly ambitious, you can do one of the following:
-
Set up a
blockstack apiendpoint (see the project README) and write a program to automatically register names. Also, see the API documentation for registering names on this endpoint. -
Write a
node.jsprogram that usesblockstack.jsto register names. This is currently in development.
Yes! Once you deploy your own subdomain registrar, you can have your Web app send it requests to register subdomains on your Blockstack ID. You can also create a program that drives subdomain registration on your Blockstack ID.
We have an integration test framework that provides a
private Blockstack testnet. It uses bitcoin -regtest to create a private
blockchain that you can interact with, without having to spend any Bitcoin or
having to wait for blocks to confirm. Please see the
README for details.
No, not yet. This is because Blockstack's design philosophy focuses on keeping system complexity at the "edges" of the network (e.g. clients), instead of the "core" of the network (e.g. the blockchain), in accordance with the end-to-end principle. Generally speaking, this can be interpreted as "if you can do X without a smart contract, you should do X without a smart contract." This organizing principle applies to a lot of useful decentralized applications.
Yes! Since Blockstack applications are built like Web applications, all you need to do is include the relevant Javascript library into your application.
Yes! See here.
Blockstack and DNS both implement naming systems, but in fundamentally different ways. Blockstack can be used for resolving host names to IP addresses, but this is not its default use-case. The Blockstack Naming Service (BNS) instead behaves more like a decentralized LDAP system for resolving user names to user data.
While DNS and BNS handle different problems, they share some terminology and serialization formats. However, it is important to recognize that this is the only thing they have in common---BNS has fundamentally different semantics than DNS:
-
Zone files: Blockstack stores a DNS zone file for each name. However, the semantics of a BNS zone file are nothing like the semantics of a DNS zone file---the only thing they have in common is their format. A "standard" Blockstack zone files only have
URIandTXTresource records that point to the user's application data. Moreover, a Blockstack ID has a history of zone files, and historic zone files can alter the way in which a Blockstack ID gets resolved (DNS has no such concept). It is conceivable that an advanced user could addAandAAAArecords to their Blockstack ID's zone file, but these are not honored by any Blockstack software at this time. -
Subdomains: Blockstack has the concept of a subdomain, but it is semantically very different from a DNS subdomain. In Blockstack, a subdomain is a Blockstack ID whose state and transaction history are anchored to the blockchain, but stored within an on-chain Blockstack ID's zone file history. Unlike DNS subdomains, a BNS subdomain has its own owner and is a first-class BNS name---all subdomains are resolvable, and only the subdomain's owner can update the subdomain's records. The only thing BNS subdomains and DNS subdomains have in common is the name format (e.g.
foo.bar.bazis a subdomain ofbar.bazin both DNS and BNS).
More details can be found in the Blockstack vs DNS document. A feature comparison can be found at the end of the Blockstack Naming Service document.
Namecoin also implements a decentralized naming service on top of a blockchain, just like BNS. In fact, early versions of Blockstack were built on Namecoin. However, it was discovered that Namecoin's merged mining with Bitcoin regularly placed it under the de facto control of a single miner. This prompted a re-architecting of the system to be portable across blockchains, so that if Blockstack's underlying blockchain (currently Bitcoin) ever became insecure, the system could migrate to a more secure blockchain.
A feature comparison can be found at the end of the Blockstack Naming Service document.
ENS also implements a decentralized naming system on top of a blockchain, but as a smart contract on Ethereum. Like BNS, ENS is geared towards resolving names to off-chain state (ENS names resolve to a hash, for example). Moreover, ENS is geared towards providing programmatic control over names with Turing-complete on-chain resolvers.
BNS has a fundamentally different relationship with blockchains than ENS. WHereas ENS tries to use on-chain logic as much as possible, BNS tries to use the blockchain as little as possible. BNS only uses it to store a database log for name operations (which are interpreted with an off-chain BNS node like Blockstack Core). BNS name state and BNS subdomains reside entirely off-chain in the Atlas network. This has allowed BNS to migrate from blockchain to blockchain in order to survive individual blockchain failures, and this has allowed BNS developers to upgrade its consensus rules without having to get the blockchain's permission (see the virtualchain paper for details).
A feature comparison can be found at the end of the Blockstack Naming Service document.
Blockstack and Ethereum both strive to provide a decentralized application platform. Blockstack's design philosophy differs from Ethereum's design philosophy in that Blockstack emphasizes treating the blockchain as a "dumb ledger" with no special functionality or properties beyond a few bare minimum requirements. Instead, it strives to do everything off-chain---an application of the end-to-end principle. Most Blockstack applications do not interact with the blockchain, and instead interact with Blockstack infrastructure through client libraries and RESTful endpoints. This is evidenced by Blockstack's decision to implement its naming system (BNS), discovery and routing system (Atlas), and storage system (Gaia) as blockchain-agnostic components that can be ported from one blockchain to another.
Ethereum takes the opposite approach. Ethereum dapps are expected to interface directly with on-chain smart contract logic, and are expected to host a non-trivial amount of state in the blockchain itself. This is necessary for them, because many Ethereum dapps' business logic is centered around the mechanics of an ERC20 token.
Blockstack does not implement a smart contract system (yet), but it will soon implement a native token that will be accessible to Blockstack applications.