chore: get rid of secp lib (#114)

* chore: get rid of secp lib

* fixup!

helpers.py

@@ -1,16 +1,16 @@
 import base64
 import secrets
 
-import secp256k1
+import coincurve
 from bech32 import bech32_decode, convertbits
-from cffi import FFI
 from cryptography.hazmat.primitives import padding
 from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
 
 
 def get_shared_secret(privkey: str, pubkey: str):
-    point = secp256k1.PublicKey(bytes.fromhex("02" + pubkey), True)
-    return point.ecdh(bytes.fromhex(privkey), hashfn=copy_x)
+    pk = coincurve.PublicKey(bytes.fromhex("02" + pubkey))
+    sk = coincurve.PrivateKey(bytes.fromhex(privkey))
+    return sk.ecdh(pk.format())
 
 
 def decrypt_message(encoded_message: str, encryption_key) -> str:
@@ -48,8 +48,8 @@ def encrypt_message(message: str, encryption_key, iv: bytes | None = None) -> st
 
 
 def sign_message_hash(private_key: str, hash_: bytes) -> str:
-    privkey = secp256k1.PrivateKey(bytes.fromhex(private_key))
-    sig = privkey.schnorr_sign(hash_, None, raw=True)
+    privkey = coincurve.PrivateKey(bytes.fromhex(private_key))
+    sig = privkey.sign_schnorr(hash_)
     return sig.hex()
 
 
@@ -64,17 +64,6 @@ def test_decrypt_encrypt(encoded_message: str, encryption_key):
     ), f"expected '{encoded_message}', but got '{ecrypted_msg}'"
 
 
-ffi = FFI()
-
-
-@ffi.callback(
-    "int (unsigned char *, const unsigned char *, const unsigned char *, void *)"
-)
-def copy_x(output, x32, y32, data):
-    ffi.memmove(output, x32, 32)
-    return 1
-
-
 def normalize_public_key(pubkey: str) -> str:
     if pubkey.startswith("npub1"):
         _, decoded_data = bech32_decode(pubkey)

nostr/event.py

@@ -2,8 +2,8 @@ import hashlib
 import json
 from typing import List, Optional
 
+from coincurve import PublicKeyXOnly
 from pydantic import BaseModel
-from secp256k1 import PublicKey
 
 
 class NostrEvent(BaseModel):
@@ -35,14 +35,14 @@ class NostrEvent(BaseModel):
                 f"Invalid event id. Expected: '{event_id}' got '{self.id}'"
             )
         try:
-            pub_key = PublicKey(bytes.fromhex("02" + self.pubkey), True)
-        except Exception:
+            pub_key = PublicKeyXOnly(bytes.fromhex(self.pubkey))
+        except Exception as exc:
             raise ValueError(
                 f"Invalid public key: '{self.pubkey}' for event '{self.id}'"
-            )
+            ) from exc
 
-        valid_signature = self.sig and pub_key.schnorr_verify(
-            bytes.fromhex(event_id), bytes.fromhex(self.sig), None, raw=True
+        valid_signature = self.sig and pub_key.verify(
+            bytes.fromhex(self.sig), bytes.fromhex(event_id)
         )
         if not valid_signature:
             raise ValueError(f"Invalid signature: '{self.sig}' for event '{self.id}'")

pyproject.toml

@@ -29,7 +29,6 @@ plugins = ["pydantic.mypy"]
 [[tool.mypy.overrides]]
 module = [
   "nostr.*",
-  "secp256k1.*",
 ]
 ignore_missing_imports = "True"