refactor: get rid of libsecp (#49)

* refactor: get rid of libsecp

* fixup!

nostr/event.py

@@ -5,7 +5,7 @@ from enum import IntEnum
 from hashlib import sha256
 from typing import Optional
 
-from secp256k1 import PublicKey
+import coincurve
 
 from .message_type import ClientMessageType
 
@@ -75,12 +75,8 @@ class Event:
     def verify(self) -> bool:
         assert self.public_key
         assert self.signature
-        pub_key = PublicKey(
-            bytes.fromhex("02" + self.public_key), True
-        )  # add 02 for schnorr (bip340)
-        return pub_key.schnorr_verify(
-            bytes.fromhex(self.id), bytes.fromhex(self.signature), None, raw=True
-        )
+        pub_key = coincurve.PublicKeyXOnly(bytes.fromhex(self.public_key))
+        return pub_key.verify(bytes.fromhex(self.signature), bytes.fromhex(self.id))
 
     def to_message(self) -> str:
         return json.dumps(

nostr/key.py

@@ -1,9 +1,7 @@
 import base64
 import secrets
-from typing import Optional
 
-import secp256k1
-from cffi import FFI
+import coincurve
 from cryptography.hazmat.primitives import padding
 from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
 
@@ -23,15 +21,13 @@ class PublicKey:
         return self.raw_bytes.hex()
 
     def verify_signed_message_hash(self, message_hash: str, sig: str) -> bool:
-        pk = secp256k1.PublicKey(b"\x02" + self.raw_bytes, True)
-        return pk.schnorr_verify(
-            bytes.fromhex(message_hash), bytes.fromhex(sig), None, True
-        )
+        pk = coincurve.PublicKeyXOnly(self.raw_bytes)
+        return pk.verify(bytes.fromhex(sig), bytes.fromhex(message_hash))
 
     @classmethod
     def from_npub(cls, npub: str):
         """Load a PublicKey from its bech32/npub form"""
-        hrp, data, spec = bech32_decode(npub)
+        _, data, _ = bech32_decode(npub)
         raw_data = convertbits(data, 5, 8)
         assert raw_data
         raw_public_key = raw_data[:-1]
@@ -39,20 +35,20 @@ class PublicKey:
 
 
 class PrivateKey:
-    def __init__(self, raw_secret: Optional[bytes] = None) -> None:
+    def __init__(self, raw_secret: bytes | None = None) -> None:
         if raw_secret is not None:
             self.raw_secret = raw_secret
         else:
             self.raw_secret = secrets.token_bytes(32)
 
-        sk = secp256k1.PrivateKey(self.raw_secret)
-        assert sk.pubkey
-        self.public_key = PublicKey(sk.pubkey.serialize()[1:])
+        sk = coincurve.PrivateKey(self.raw_secret)
+        assert sk.public_key
+        self.public_key = PublicKey(sk.public_key.format()[1:])
 
     @classmethod
     def from_nsec(cls, nsec: str):
         """Load a PrivateKey from its bech32/nsec form"""
-        hrp, data, spec = bech32_decode(nsec)
+        _, data, _ = bech32_decode(nsec)
         raw_data = convertbits(data, 5, 8)
         assert raw_data
         raw_secret = raw_data[:-1]
@@ -66,12 +62,13 @@ class PrivateKey:
         return self.raw_secret.hex()
 
     def tweak_add(self, scalar: bytes) -> bytes:
-        sk = secp256k1.PrivateKey(self.raw_secret)
-        return sk.tweak_add(scalar)
+        sk = coincurve.PrivateKey(self.raw_secret)
+        return sk.add(scalar).to_der()
 
     def compute_shared_secret(self, public_key_hex: str) -> bytes:
-        pk = secp256k1.PublicKey(bytes.fromhex("02" + public_key_hex), True)
-        return pk.ecdh(self.raw_secret, hashfn=copy_x)
+        pk = coincurve.PublicKey(bytes.fromhex("02" + public_key_hex))
+        sk = coincurve.PrivateKey(self.raw_secret)
+        return sk.ecdh(pk.format())
 
     def encrypt_message(self, message: str, public_key_hex: str) -> str:
         padder = padding.PKCS7(128).padder()
@@ -116,8 +113,8 @@ class PrivateKey:
         return unpadded_data.decode()
 
     def sign_message_hash(self, message_hash: bytes) -> str:
-        sk = secp256k1.PrivateKey(self.raw_secret)
-        sig = sk.schnorr_sign(message_hash, None, raw=True)
+        sk = coincurve.PrivateKey(self.raw_secret)
+        sig = sk.sign_schnorr(message_hash)
         return sig.hex()
 
     def sign_event(self, event: Event) -> None:
@@ -131,9 +128,7 @@ class PrivateKey:
         return self.raw_secret == other.raw_secret
 
 
-def mine_vanity_key(
-    prefix: Optional[str] = None, suffix: Optional[str] = None
-) -> PrivateKey:
+def mine_vanity_key(prefix: str | None = None, suffix: str | None = None) -> PrivateKey:
     if prefix is None and suffix is None:
         raise ValueError("Expected at least one of 'prefix' or 'suffix' arguments")
 
@@ -149,14 +144,3 @@ def mine_vanity_key(
         break
 
     return sk
-
-
-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

pyproject.toml

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