Add Event.note_id bech32 format property (#49)

Author: kdmukai

nostr/event.py

@@ -3,9 +3,10 @@
 from dataclasses import dataclass, field
 from enum import IntEnum
 from typing import List
-from secp256k1 import PrivateKey, PublicKey
+from secp256k1 import PublicKey
 from hashlib import sha256
 
+from . import bech32
 from .message_type import ClientMessageType
 
 
@@ -57,6 +58,12 @@ def id(self) -> str:
         return Event.compute_id(self.public_key, self.created_at, self.kind, self.tags, self.content)
 
 
+    @property
+    def note_id(self) -> str:
+        converted_bits = bech32.convertbits(bytes.fromhex(self.id), 8, 5)
+        return bech32.bech32_encode("note", converted_bits, bech32.Encoding.BECH32)
+
+
     def add_pubkey_ref(self, pubkey:str):
         """ Adds a reference to a pubkey as a 'p' tag """
         self.tags.append(['p', pubkey])

test/test_event.py

@@ -1,5 +1,7 @@
 import pytest
 import time
+
+from nostr import bech32
 from nostr.event import Event, EncryptedDirectMessage
 from nostr.key import PrivateKey
 
@@ -36,6 +38,44 @@ def test_event_id_recomputes(self):
         assert event.id != event_id
 
 
+    def test_note_id_bech32_conversion(self):
+        """ should convert the event id to its `note`-prepended bech32 form """
+        event = Event(content="some event")
+        assert event.note_id.startswith("note")
+
+        # reverse the bech32 encoding
+        hrp, data, spec = bech32.bech32_decode(event.note_id)
+        raw_event_id = bech32.convertbits(data, 5, 8)[:-1]
+
+        # Should get the same event_id back
+        assert event.id == bytes(raw_event_id).hex()
+    
+
+    def test_note_id_conformity(self):
+        """ should produce the same note ID as a known published note """
+        """
+            A real-world note from fiatjaf:
+            {
+                "id": "deb8b23368b6c658c36cf16396927a045dee0b7707b4133d714fb67264cc10cc",
+                "kind": 1,
+                "pubkey": "3bf0c63fcb93463407af97a5e5ee64fa883d107ef9e558472c4eb9aaaefa459d",
+                "created_at": 1673361254,
+                "content": "hello",
+                "tags": [],
+                "sig": "f5e5e8a477c6749ef8562c23cdfec7a6917c975ec55075489cb3319b8a2ccb78317335a6850fb3a3714777b1c22611419d6c81ce4b0b88db86e2d1662bb17540"
+            }
+        """
+        event = Event(
+            content="hello",
+            public_key="3bf0c63fcb93463407af97a5e5ee64fa883d107ef9e558472c4eb9aaaefa459d",
+            created_at=1673361254,
+            kind=1,
+            signature="f5e5e8a477c6749ef8562c23cdfec7a6917c975ec55075489cb3319b8a2ccb78317335a6850fb3a3714777b1c22611419d6c81ce4b0b88db86e2d1662bb17540"
+        )
+        assert event.id == "deb8b23368b6c658c36cf16396927a045dee0b7707b4133d714fb67264cc10cc"
+        assert event.note_id == "note1m6utyvmgkmr93smv793edyn6q3w7uzmhq76px0t3f7m8yexvzrxqw46k83"
+
+
     def test_add_event_ref(self):
         """ should add an 'e' tag for each event_ref added """
         some_event_id = "some_event_id"