# Decentralized Identity

Self-sovereign identity systems that enable trust and coordination without centralized authorities — proving who you are and what you've done through portable, user-controlled credentials.

**Decentralized Identity (DID)** encompasses systems that allow individuals to create, own, and control their digital identities without relying on centralized authorities. As a coordination mechanism, decentralized identity enables trust, reputation, and Sybil resistance in permissionless environments — essential infrastructure for democratic allocation mechanisms that need to distinguish unique humans from bots and duplicate accounts.

## How It Works

1. **Identity creation** — users generate cryptographic identifiers they control (DIDs, wallet addresses, etc.)  
2. **Credential accumulation** — attestations, verifications, and proofs are attached to the identity by issuers (organizations, protocols, peers)  
3. **Selective disclosure** — users choose which credentials to reveal in which contexts, maintaining privacy  
4. **Verification** — relying parties can verify credentials cryptographically without contacting the issuer  
5. **Reputation emerges** — over time, identities accumulate verifiable history that builds trust

## Advantages

- User sovereignty — individuals control their own identity data  
- Portable — credentials work across platforms, protocols, and communities  
- Sybil-resistant — verifiable credentials make it expensive to create convincing fake identities  
- Privacy-preserving — selective disclosure and zero-knowledge proofs reveal only what's needed  
- Enables democratic mechanisms — one-person-one-vote requires proving unique personhood

## Limitations

- Cold start problem — new identities have no credentials or reputation  
- Credential fragmentation — no universal standard adopted across the ecosystem  
- Key management burden shifts to users, who may lose access  
- Sophisticated attackers can still create multiple identities through credential farms  
- Tension between privacy and accountability

## Best Used When

- Sybil resistance is needed for democratic governance or quadratic mechanisms  
- Participants need portable reputation across multiple platforms  
- Privacy-preserving identity verification is required  
- Building trust in permissionless environments where traditional identity verification is impractical

## Examples and Use Cases

**Gitcoin Passport** aggregates identity stamps from multiple sources (ENS, social accounts, biometric verification) to generate a Sybil-resistance score used in quadratic funding rounds.

**Ethereum Name Service (ENS)** provides human-readable identities linked to Ethereum addresses, serving as a foundational identity layer.

**Worldcoin/World ID** uses biometric proof-of-personhood to establish unique human identity for democratic mechanisms.

**Verifiable Credentials (W3C standard)** provide a specification for issuing and verifying portable, cryptographic credentials across systems.

### Tags

identity, sybil-resistance, trust, infrastructure