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

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