window.nostr - NIP-07 Shim

A lightweight shim for the window.nostr interface implementing NIP-07 for Nostr-enabled web applications. This shim includes key management, event signing, and basic encryption/decryption, all in the browser using localStorage to store the private key.

Features

• Implements the NIP-07 interface (getPublicKey, signEvent, getRelays)
• Stores the private key in localStorage (nostr:privkey)
• Uses secp256k1 for public/private key generation and event signing
• Basic NIP-04 encryption/decryption using shared secrets
• Works entirely in the browser without external dependencies (other than cryptography)
• Modular and extendable

Installation

You can install this shim via npm:

npm install window-nostr

Or include it directly in your HTML as a script using ES modules:

<script type="module">
  import * as secp256k1 from 'https://esm.sh/noble-secp256k1'
  import 'https://cdn.jsdelivr.net/npm/window-nostr'
</script>

Usage

Once included, the window.nostr object will be available globally. Here are some examples of its usage:

Get the Public Key

window.nostr.getPublicKey().then(pubKey => {
  console.log('Public Key:', pubKey)
})

Sign a Nostr Event

const event = {
  id: 'some-event-id',
  content: 'Hello, Nostr!',
  created_at: Math.floor(Date.now() / 1000),
  kind: 1,
  pubkey: 'example-pubkey',
  tags: []
}

window.nostr.signEvent(event).then(signedEvent => {
  console.log('Signed Event:', signedEvent)
})

Get Relay Information

window.nostr.getRelays().then(relays => {
  console.log('Relays:', relays)
})

Encrypt a Message (NIP-04)

const recipientPubKey = 'recipient-public-key'
const message = 'Hello, this is a secret message.'

window.nostr.nip04.encrypt(recipientPubKey, message).then(ciphertext => {
  console.log('Encrypted Message:', ciphertext)
})

Decrypt a Message (NIP-04)

const recipientPubKey = 'recipient-public-key'
const encryptedMessage = 'encrypted_message_string'

window.nostr.nip04
  .decrypt(recipientPubKey, encryptedMessage)
  .then(plaintext => {
    console.log('Decrypted Message:', plaintext)
  })

Key Management

• The private key is stored in localStorage under the key nostr:privkey. If no private key is found, a new one is generated automatically and stored for future use.
• The public key is derived from the stored private key and is returned via window.nostr.getPublicKey().

To clear or reset the private key, simply remove it from localStorage:

localStorage.removeItem('nostr:privkey')

How It Works

1. Private Key Management: The private key is securely stored in localStorage. If no key is found, the shim generates one using the secp256k1 elliptic curve.

2. Public Key: The public key is derived from the private key using the getPublicKey() method and returned in hex format.

3. Event Signing: Events are serialized and signed using the private key. The signature is added to the event as sig.

4. Relays: The getRelays() method returns a mock relay configuration. This can be customized to support real-world relays.

5. Encryption/Decryption: The nip04.encrypt() and nip04.decrypt() methods use a shared secret derived from the sender's private key and the recipient's public key to "encrypt" and "decrypt" messages (currently mocked for simplicity).

Dependencies

• noble-secp256k1 - A fast, secure, and pure JavaScript implementation of the secp256k1 elliptic curve, which is used for generating key pairs and signing messages.

License

MIT License

Feel free to contribute, submit issues, or request features! Let's build the future of decentralized communication together.