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The @credo-ts/core package provides the foundational functionality for all Credo agents. This is a required dependency that includes essential services, APIs, and protocols.

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Installation

npm install @credo-ts/core

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What’s Included

The core package provides:

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Agent Framework

  • Agent - Main agent class and lifecycle management
  • Module system - Plugin architecture for extending functionality
  • Dependency injection - Container for managing services
  • Event system - Event emitter for agent events

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DID Management

  • DID resolver - Resolve DIDs across multiple methods
  • DID registrar - Create and update DIDs
  • Supported DID methods:
    • did:key - Cryptographic key-based DIDs
    • did:peer - Peer DIDs for pairwise relationships
    • did:web - Web-based DIDs
    • Extensible via modules (did:indy, did:cheqd, etc.)

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Verifiable Credentials

  • W3C Verifiable Credentials - Data Integrity and JWT formats
  • SD-JWT VC - Selective disclosure JWT credentials
  • mDocs/mDL - Mobile document credentials (ISO 18013-5)
  • Presentation Exchange - DIF Presentation Exchange v2
  • DCQL - Digital Credentials Query Language

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Cryptography

  • Key types: Ed25519, X25519, P-256, P-384, P-521, RSA
  • JWS/JWT - JSON Web Signatures and Tokens
  • Data Integrity - Linked Data Proofs
  • Key Management - Abstract KMS interface (implemented by modules)

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Storage

  • Abstract storage interface - Implemented by storage modules
  • Record management - Generic record storage
  • Migrations - Version-based storage updates
  • Caching - Optional caching layer

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Basic Usage

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Creating an Agent

import { Agent } from '@credo-ts/core'
import { agentDependencies } from '@credo-ts/node'
import { AskarModule } from '@credo-ts/askar'
import { ariesAskar } from '@hyperledger/aries-askar-nodejs'

const agent = new Agent({
  config: {
    label: 'My Agent',
    walletConfig: {
      id: 'my-wallet-id',
      key: 'my-secret-wallet-key',
    },
  },
  dependencies: agentDependencies,
  modules: {
    askar: new AskarModule({ ariesAskar }),
  },
})

await agent.initialize()

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Working with DIDs

// Create a did:key
const didResult = await agent.dids.create({
  method: 'key',
  options: {
    keyType: 'ed25519',
  },
})

console.log(didResult.didState.did)
// did:key:z6MkpTHR8VNsBxYAAWHut2Geadd9jSwuBV8xRoAnwWsdvktH

// Resolve a DID
const didDocument = await agent.dids.resolve('did:key:z6Mkk...')

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Issuing W3C Verifiable Credentials

import { ClaimFormat, W3cCredentialService } from '@credo-ts/core'

const w3cCredentialService = agent.dependencyManager.resolve(W3cCredentialService)

const signedCredential = await w3cCredentialService.signCredential(agentContext, {
  format: ClaimFormat.JwtVc,
  credential: {
    '@context': ['https://www.w3.org/2018/credentials/v1'],
    type: ['VerifiableCredential'],
    issuer: issuerDid,
    issuanceDate: new Date().toISOString(),
    credentialSubject: {
      id: holderDid,
      name: 'Alice',
    },
  },
  verificationMethod: verificationMethod.id,
})

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Verifying Credentials

const result = await w3cCredentialService.verifyCredential(agentContext, {
  credential: signedCredential,
})

if (result.verified) {
  console.log('Credential is valid!')
}

​
Using SD-JWT Credentials

import { SdJwtVcService } from '@credo-ts/core'

const sdJwtVcService = agent.dependencyManager.resolve(SdJwtVcService)

// Issue SD-JWT VC
const { compact } = await sdJwtVcService.sign(agentContext, {
  holder: { method: 'did', didUrl: holderDid },
  issuer: { method: 'did', didUrl: issuerDid },
  payload: {
    vct: 'IdentityCredential',
    given_name: 'Alice',
    family_name: 'Smith',
    age: 30,
  },
  disclosureFrame: {
    _sd: ['given_name', 'family_name', 'age'],
  },
})

// Present with selective disclosure
const presentation = await sdJwtVcService.present(agentContext, {
  compactSdJwtVc: compact,
  presentationFrame: {
    given_name: true,
    age: true,
  },
})

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Agent Configuration

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Config Options

import type { InitConfig } from '@credo-ts/core'

const config: InitConfig = {
  label: 'Agent Label',
  walletConfig: {
    id: 'wallet-id',
    key: 'wallet-key',
  },
  
  // Optional configurations
  logger: customLogger,
  endpoints: ['https://example.com'],
  autoUpdateStorageOnStartup: true,
  allowInsecureHttpUrls: false,
  connectionImageUrl: 'https://example.com/logo.png',
}

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Events

Subscribe to agent events: 
import { CredentialEventTypes, CredentialState } from '@credo-ts/core'

agent.events.on(CredentialEventTypes.CredentialStateChanged, (event) => {
  if (event.payload.credentialRecord.state === CredentialState.Done) {
    console.log('Credential exchange completed!')
  }
})

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API Structure

Core services available:
  • agent.dids - DID operations
  • agent.genericRecords - Generic record storage
  • agent.wallet - Wallet operations
  • agent.w3cCredentials - W3C credential operations
  • agent.sdJwtVc - SD-JWT VC operations
  • agent.mdoc - mDoc operations
  • agent.x509 - X.509 certificate operations
  • agent.cache - Caching operations

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Storage Service

The core requires a storage implementation. Use one of:
  • @credo-ts/askar - Aries Askar (recommended)
  • @credo-ts/drizzle-storage - Drizzle ORM based storage
  • Custom implementation of StorageService

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Source Code

View the source code at:

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