basic functionality, untested.

extension/nostr-provider.js

@@ -1,4 +1,45 @@
 window.nostr = {
-  getPublicKey() {},
-  signEvent(event) {}
+  _requests: {},
+  _pubkey: null,
+
+  async getPublicKey() {
+    if (this._pubkey) return this._pubkey
+    this._pubkey = await this._call('getPublicKey')
+    return this._pubkey
+  },
+
+  async signEvent(event) {
+    return this._call('signEvent', {event})
+  },
+
+  _call(type, params) {
+    return new Promise((resolve, reject) => {
+      let id = Math.random().toString().slice(4)
+      this._requests[id] = {resolve, reject}
+      window.postMessage(
+        {
+          id,
+          ext: 'nos2x',
+          type,
+          params
+        },
+        '*'
+      )
+    })
+  }
 }
+
+window.addEventListener('message', message => {
+  if (
+    !message.data ||
+    message.data.ext !== 'nos2x' ||
+    !window.nostr._requests[message.data.id]
+  )
+    return
+
+  if (message.data.response.error) {
+    window.nostr._requests[message.data.id].reject(message.data.response.error)
+  } else {
+    window.nostr._requests[message.data.id].resolve(message.data.response)
+  }
+})