What is a Decentralized Identifier
A Decentralized Identifier (DID) is a new type of globally unique ID that is controlled by the user, not a centralized company. It's the foundation of a new, self-sovereign digital identity.
A Decentralized Identifier (DID) is a new type of identifier for the digital world that is globally unique, verifiable, and not controlled by any centralized authority. It is a core component of Self-Sovereign Identity (SSI), a movement to give individuals control over their own digital identities.
Think of a DID as a phone number that you own and control yourself, rather than one that is issued to you by a phone company. It's a permanent, portable address for you on the internet.
The Problem with Traditional Identifiers
In the Web2 world, our digital identities are fragmented and controlled by others.
- Your email address (
username@gmail.com) is controlled by Google. - Your social media handle (
@username) is controlled by Twitter or Facebook.
These companies can take away your identifier, censor you, or monetize your data without your permission. You don't truly own your online identity.
How DIDs Work
A DID is a simple text string that looks something like this: did:example:123456789abcdefghi
It has three parts:
- The Scheme:
did:- This just identifies it as a DID. - The DID Method:
example:- This specifies the particular blockchain or DLT where the DID's records are stored. There are many different methods, likedid:ethr:for Ethereum ordid:btcr:for Bitcoin. - The Method-Specific Identifier:
123456789abcdefghi- This is a unique string generated by the specific DID method, often derived from a cryptographic public key.
The DID Document: The "Business Card"
The DID itself is just an address. The magic happens when it is "resolved" to a DID Document. This is a JSON file associated with the DID that contains crucial information:
- Cryptographic Public Keys: The public keys that can be used to verify signatures made by the DID's controller (the user).
- Authentication Methods: Information on how the DID's controller can authenticate themselves (e.g., by signing a message with a specific key).
- Service Endpoints: URLs for services related to the DID, such as a location to store data or a way to communicate with the DID's owner.
A user creates a DID and its associated DID Document and then registers it on the target blockchain. The user controls the private key associated with the public keys in the DID Document, which means only they can make updates to it.
Why DIDs Matter for Web3
DIDs are a foundational building block for a more private and user-centric internet.
- User Control: You own your identifier. No one can take it away from you.
- Portability: You can use the same DID across many different applications and services. Your reputation and history are portable, not locked into a single platform.
- Privacy: DIDs are pseudonymous by default. They are not directly linked to your real-world identity unless you choose to make that link.
- Enabling Verifiable Credentials: DIDs are the foundation upon which Verifiable Credentials are built. A university can issue a "Digital Diploma" credential to your DID, and you can then use your DID to prove to an employer that you have that degree, without the employer ever needing to contact the university.
Decentralized Identifiers are a simple but powerful concept. They shift the control of online identity from centralized platforms to the individual, creating a more secure, private, and interoperable digital world.
Frequently Asked Questions
1. Is my DID my wallet address?
They are very closely related and can be the same thing. For example, the did:ethr method uses an Ethereum address as the method-specific identifier. Your wallet address is a type of DID.
2. Where is my DID stored?
The DID and its associated DID Document are registered on a public blockchain or another type of distributed ledger. This makes it publicly discoverable and verifiable.
3. How is a DID different from using "Sign in with Google"?
When you use "Sign in with Google," Google is the central authority that controls your identity. With a DID, you are the authority. You control your own keys and your own data.
4. What is Self-Sovereign Identity (SSI)?
SSI is the broad movement and philosophy that individuals should have ultimate control over their own digital identities. DIDs are the core technical standard for implementing SSI.
5. What is a "Verifiable Credential"?
A Verifiable Credential is a tamper-proof digital claim or attestation made about a DID by an issuer. For example, a government could issue a credential to your DID that verifies you are over 18. This is a key part of building a useful decentralized identity system.
