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ContextVM Documentation

NostrSigner Interface

NostrSigner Interface

Section titled “NostrSigner Interface”

The NostrSigner interface is a central component of the @contextvm/sdk, defining the standard for cryptographic signing operations. Every Nostr event must be signed by a private key to be considered valid, and this interface provides a consistent, pluggable way to handle this requirement.

Purpose and Design

Section titled “Purpose and Design”

The primary purpose of the NostrSigner is to abstract the process of event signing. By depending on this interface rather than a concrete implementation, the SDK’s transports and other components can remain agnostic about how and where private keys are stored and used.

This design offers several key benefits:

  • Security: Private keys can be managed in secure environments (e.g., web extensions, hardware wallets, dedicated signing services) without exposing them to the application logic.
  • Flexibility: Developers can easily swap out the default signer with a custom implementation that meets their specific needs.
  • Modularity: The signing logic is decoupled from the communication logic, leading to a cleaner, more maintainable codebase.

Interface Definition

Section titled “Interface Definition”

The NostrSigner interface is defined in core/interfaces.ts.

export interface NostrSigner {
  getPublicKey(): Promise<string>;
  signEvent(event: EventTemplate): Promise<NostrEvent>;


  // Optional NIP-04 encryption support (deprecated)
  nip04?: {
    encrypt: (pubkey: string, plaintext: string) => Promise<string>;
    decrypt: (pubkey: string, ciphertext: string) => Promise<string>;
  };


  // Optional NIP-44 encryption support
  nip44?: {
    encrypt: (pubkey: string, plaintext: string) => Promise<string>;
    decrypt: (pubkey: string, ciphertext: string) => Promise<string>;
  };
}
  • getPublicKey(): Asynchronously returns the public key corresponding to the signer’s private key.
  • signEvent(event): Takes an unsigned Nostr event, signs it, and returns the signature.
  • nip04: (Deprecated) Provides NIP-04 encryption support.
  • nip44: Provides NIP-44 encryption support.

Any class that implements this interface can be used as a signer throughout the SDK.

Implementations

Section titled “Implementations”

The SDK provides a default implementation for common use cases and allows for custom implementations for advanced scenarios.

  • PrivateKeySigner: The default implementation, which takes a raw private key string and performs signing operations locally.
  • Custom Signer Development: For creating custom signers that integrate with key management systems, such as hardware wallets or remote signing services.

Next Steps

Section titled “Next Steps”