Decentralised Identity (DID)

Decentralised Identity (DID) is a framework for creating self-sovereign identities on blockchain networks without reliance on centralized authorities.

What is DID?

A Decentralised Identity is a digital identity that is:

• User-Controlled: You own and manage your identity directly without intermediaries
• Portable: Your identity works across multiple platforms, services, and blockchain networks
• Verifiable: Your identity can be cryptographically verified by others
• Privacy-Preserving: You control what information is revealed and to whom
• Persistent: Your identity persists even if a single service goes down

DID Standards

W3C DID Specification

The W3C (World Wide Web Consortium) defines a standard format for DIDs:

did:method:method-specific-id

Example:

did:eth:0x1234567890123456789012345678901234567890

Where:

• did - Scheme identifier
• eth - Method (Ethereum-based)
• 0x1234... - Method-specific identifier (Ethereum address)

How ERC-7866 Enables DID

ERC-7866 implements a practical DID system for Ethereum by providing:

1. Human-Readable Identifiers

Instead of raw wallet addresses, users claim memorable usernames:

alice@eth.soul
bob@polygon.soul

2. Cryptographic Verification

Usernames are tied to wallet addresses, creating a verifiable on-chain identity:

• Username → Address mapping
• Address → Profile data retrieval
• Signature verification for ownership

3. Cross-Chain Portability

The same username format works across all EVM chains:

• alice@eth.soul on Ethereum
• alice@polygon.soul on Polygon
• alice@arb.soul on Arbitrum

All pointing to the same user with consistent identity.

4. Privacy Control

Users control visibility of their profile data:

• Public profiles accessible to everyone
• Private profiles hidden from unauthorized access
• Selective disclosure of information

DID Use Cases

Professional Identity

Maintain separate identities for work and personal life:

• Work profile: Professional credentials, portfolio
• Personal profile: Social presence, gaming avatars

Reputation Systems

Build verifiable reputation across platforms:

• DeFi lending: Credit history tied to on-chain identity
• Gaming: Achievement and rank tied to gaming profile
• DAO governance: Voting history tied to member identity

Social Discovery

Find and connect with users:

• Search by username instead of address
• Discover users by avatar or profile info
• Build social networks around on-chain identity

Service Access Control

Grant access based on verified identity:

• NFT drops to specific usernames
• Whitelist addresses by identity
• Permission-based access to services

DID vs. Web2 Identity

Aspect	Web2	DID (ERC-7866)
Control	Centralized platform	User-owned
Portability	Platform-specific	Cross-platform
Verification	Email, phone	Cryptographic
Privacy	Platform-managed	User-controlled
Censorship	Platform can revoke	Blockchain immutable
Cost	Free (but your data is product)	Small on-chain cost

DID Architecture with ERC-7866

The diagram illustrates how ERC-7866 enables decentralised identity:

1. User Claims Username → Creates on-chain identity
2. Sets Profile Data → Avatar, bio, metadata (on IPFS/Arweave)
3. Creates dApp Avatars → Different identities per application
4. Other Users Verify → Query on-chain profile by username or address
5. Services Integrate → Games, DAOs, DeFi can use identity

Security Considerations

Non-Transferability

Usernames are soul-bound to addresses:

• Cannot be sold or transferred
• Prevents identity hijacking
• Ensures persistent reputation

Immutable Records

Once created, profile history is permanent:

• Cannot erase past actions
• Promotes accountability
• Enables trustworthy reputation

On-Chain Proof

All identity claims are cryptographically verified:

• No fake identities
• Proof of ownership via signature
• Verifiable by smart contracts

Privacy in DID

ERC-7866 balances transparency with privacy:

Public Avatars

Visible to all users:

• Professional profiles
• Gaming achievements
• Social identities

Private Avatars

Hidden from public view:

• Sensitive information
• Context-specific data
• Personal preferences

Selective Disclosure

You control what's revealed:

• Show profile to specific addresses
• Time-limited access
• Conditional disclosure

Future of DID

Cross-Chain Identity

• Unified identity across all blockchains
• Interoperable DID standards
• Multi-chain reputation systems

Privacy Enhancements

• Zero-knowledge proofs for selective disclosure
• Anonymous credentials
• Privacy-preserving verification

Integration with Web3

• Wallet connections using DID
• Decentralized authentication
• Identity-based access control

Getting Started

To implement DID using ERC-7866:

1. Deploy SoulProfile contract on your target chain
2. Create a profile with your chosen username
3. Set avatars for different applications
4. Share your username with others
5. Integrate into your service to verify user identities

See the Implementation Guide for code examples.

Learn More

• W3C DID Specification
• EIP-7866 Specification
• Implementation Guide
• Security Considerations