Add abstraction for a cryptographic key

libp2p/crypto/secp256k1.py

@@ -0,0 +1,54 @@
+from typing import Tuple
+
+import coincurve
+
+from libp2p.crypto.keys import KeyType, PrivateKey, PublicKey
+
+
+class Secp256k1PublicKey(PublicKey):
+    def __init__(self, impl: coincurve.PublicKey) -> None:
+        self.impl = impl
+
+    def to_bytes(self) -> bytes:
+        return self.impl.format()
+
+    def get_type(self) -> KeyType:
+        return KeyType.Secp256k1
+
+    def verify(self, data: bytes, signature: bytes) -> bool:
+        raise NotImplementedError
+
+
+class Secp256k1PrivateKey(PrivateKey):
+    def __init__(self, impl: coincurve.PrivateKey) -> None:
+        self.impl = impl
+
+    @classmethod
+    def new(cls, secret: bytes = None) -> "Secp256k1PrivateKey":
+        private_key_impl = coincurve.PrivateKey()
+        return cls(private_key_impl)
+
+    def to_bytes(self) -> bytes:
+        return self.impl.secret
+
+    def get_type(self) -> KeyType:
+        return KeyType.Secp256k1
+
+    def sign(self, data: bytes) -> bytes:
+        raise NotImplementedError
+
+    def get_public_key(self) -> PublicKey:
+        public_key_impl = coincurve.PublicKey.from_secret(self.impl.secret)
+        return Secp256k1PublicKey(public_key_impl)
+
+
+def create_new_key_pair(secret: bytes = None) -> Tuple[PrivateKey, PublicKey]:
+    """
+    Returns a new Secp256k1 keypair derived from the provided ``secret``,
+    a sequence of bytes corresponding to some integer between 0 and the group order.
+
+    A valid secret is created if ``None`` is passed.
+    """
+    private_key = Secp256k1PrivateKey.new()
+    public_key = private_key.get_public_key()
+    return private_key, public_key