Crypto Gloss

Decentralized Identity

Decentralized identity describes ways for people, organizations, or devices to use identifiers and digital credentials across services without relying on one identity provider to control every step. It is an approach, not one product or blockchain. Some systems use distributed ledgers; others use different registries or infrastructure. “User-controlled” also does not automatically mean private, portable, recoverable, or accepted by every service.

The main building blocks

Decentralized identifiers

A decentralized identifier (DID) is a type of identifier with a method-specific form, such as did:method:identifier. A resolver uses that method to look up a DID document, which can contain public keys and service information used to interact with the subject. DID methods specify how identifiers are created, resolved, updated, or deactivated. The W3C DID standard notes that many, but not all, methods use distributed-ledger technology.

Verifiable credentials

A verifiable credential is a digitally signed statement from an issuer, such as a school, employer, or public agency. A holder keeps the credential and may present it to a verifier, which checks its cryptographic proof and status. The verifier still decides whether to trust the issuer and whether the claim is suitable for its purpose. As the W3C credential model stresses, verifying a credential does not prove that its claims are true.

Wallets and presentations

A wallet or agent may store credentials, manage keys, and prepare presentations for a service. Depending on the format and implementation, a presentation can disclose an entire credential, selected attributes, or a derived proof. Selective disclosure and zero-knowledge techniques can reduce what is revealed in some systems, but they are not automatic properties of every DID or credential.

How this differs from wallet sign-in

Sign-In with Ethereum (SIWE) lets a website ask a user to sign a structured message to prove control of an Ethereum address for a session. A correct flow checks the requesting domain, nonce, message fields, and signature. That proves control of a key under the protocol; by itself, it does not establish a person’s legal identity, credentials, or reputation. Human-readable names such as ENS can make an address easier to use and can resolve associated records, but public records can also make an address easier to link to its on-chain activity.

What can be useful about decentralized identity

  • Credentials can be carried between compatible services rather than reissued for every application.
  • A verifier can sometimes check a signed credential without contacting the issuer for every presentation, subject to the credential’s status and design.
  • Different DID methods and credential formats can support different trust, storage, and privacy needs.
  • Some presentations can disclose only the information needed for a particular check.

Limits and privacy risks

Decentralized identity does not remove the need to trust credential issuers, wallet software, resolvers, verifiers, or the rules that govern revocation and recovery. A valid signature only shows that the credential was signed and has not failed the relevant checks; it does not make a false statement accurate. Losing a device or key can block access, while a poor recovery process can create a new central point of control.

Identifiers and public keys can also link activity across services. A public name, DID document, service endpoint, or repeated credential identifier may expose personal details or let observers correlate separate interactions. The W3C DID standard specifically warns implementers to keep personal data out of public DID documents and consider correlation risks. Storing personal information on an immutable public ledger can make correction or removal difficult.

Questions to ask about an identity system

  • Who issues the credential, and how does a verifier decide whether that issuer is trustworthy?
  • Where are credentials and personal information stored, and what becomes public?
  • Can credentials expire or be revoked, and can a status check reveal when or where a person presents one?
  • What happens if a user loses a device, key, or account?
  • Which other wallets, DID methods, credential formats, and services can actually interoperate with it?

Social Media Sentiment

A March 2025 r/ethereum discussion about decentralized-identity projects shared a visualization of projects connected with Ethereum. Some replies were interested in the ecosystem, while others asked why an identity use case needs a blockchain if a conventional database may be cheaper or faster; responses pointed to tamper-resistant key discovery and also mentioned fees and throughput. This was a small technical discussion, not a survey, and the thread’s project counts were not independently audited for this summary.

Last updated: 2026-10

Related Terms

  • Ethereum Name Service — a naming and resolution system that can make blockchain addresses easier to use.
  • Smart Contract — code deployed on a blockchain, which may support some identity functions.
  • Zero-Knowledge Proof — a cryptographic method that can support limited proofs without revealing all underlying data.

See Also

Sources