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Concepts

The FastAuth Browser SDK is designed with a modular architecture that separates concerns between authentication, signing, and blockchain interactions. This section provides a high-level overview of the core components and their relationships.

Architecture Overview​

Core Components​

FastAuthClient​

The FastAuthClient is the main orchestrator and entry point for the SDK. It provides a unified interface for authentication and transaction operations.

Key Responsibilities:

  • Manages the authentication lifecycle (login/logout)
  • Creates and configures signer instances
  • Abstracts provider-specific implementations
  • Enforces authentication requirements before transaction operations

FastAuthProvider​

The FastAuthProvider interface defines the contract for authentication providers. This abstraction allows the SDK to support multiple authentication backends.

Key Capabilities:

  • Authentication state management (isLoggedIn())
  • Login/logout operations
  • Transaction signature requests
  • Cryptographic path derivation

Provider Types:

  • Auth0Provider: Integration with Auth0 authentication service
  • CustomProvider: Support for custom authentication backends

FastAuthSigner​

The FastAuthSigner handles all transaction-related operations and blockchain interactions. It bridges the authentication layer with NEAR blockchain functionality.

Key Features:

  • Transaction signing and submission
  • Account creation operations
  • Delegate action handling
  • Public key derivation from MPC contracts

Transaction Types:

  • Standard NEAR transactions
  • Delegate actions for gasless transactions
  • Account creation with public key registration

NEAR Connection​

The NEAR Connection (from near-api-js) provides the blockchain connectivity layer.

Responsibilities:

  • Network communication with NEAR blockchain
  • Contract method calls and queries
  • Transaction broadcasting
  • Block and state queries

Component Interactions​

Authentication Flow​

  1. Client receives login request from application
  2. Client delegates to Provider for authentication
  3. Provider handles authentication mechanism (OAuth, custom, etc.)
  4. Provider maintains authentication state

Transaction Flow​

  1. Application requests Signer from Client
  2. Client verifies authentication status via Provider
  3. Client creates and initializes Signer instance
  4. Signer uses Provider for signature requests
  5. Signer interacts with NEAR contracts via Connection

Key Benefits​

Modularity: Each component has a single responsibility, making the SDK maintainable and testable.

Extensibility: The provider pattern allows easy integration of new authentication mechanisms.

Type Safety: Generic types ensure compile-time validation across component interactions.

Separation of Concerns: Authentication, signing, and blockchain interactions are cleanly separated.

Provider Abstraction: Applications can switch authentication providers without changing business logic.

Integration Points​

Smart Contracts​

  • MPC Contract: Handles multi-party computation for key derivation
  • FastAuth Contract: Manages authentication and signature verification

External Services​

  • Authentication Providers: Auth0, custom backends, identity providers
  • NEAR Network: Mainnet, testnet, or custom networks
  • Browser APIs: LocalStorage, SessionStorage for state persistence