added ed25519 wrapper

src/allmydata/crypto/ed25519.py

@@ -0,0 +1,64 @@
+import six
+
+from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey, Ed25519PublicKey
+from cryptography.hazmat.primitives.serialization import Encoding, PrivateFormat, NoEncryption, \
+    PublicFormat
+
+
+class SigningKey:
+
+    def __init__(self, priv_key):
+        if not isinstance(priv_key, Ed25519PrivateKey):
+            raise ValueError('priv_key must be an Ed25519PrivateKey')
+        self._priv_key = priv_key
+
+    @classmethod
+    def generate(cls):
+        return cls(Ed25519PrivateKey.generate())
+
+    @classmethod
+    def from_private_bytes(cls, priv_bytes):
+        if not isinstance(priv_bytes, six.binary_type):
+            raise ValueError('priv_bytes must be bytes')
+        return SigningKey(Ed25519PrivateKey.from_private_bytes(priv_bytes))
+
+    def private_bytes(self):
+        return self._priv_key.private_bytes(
+            Encoding.Raw,
+            PrivateFormat.Raw,
+            NoEncryption(),
+        )
+
+    def public_key(self):
+        return VerifyingKey(self._priv_key.public_key())
+
+    def sign(self, data):
+        if not isinstance(data, six.binary_type):
+            raise ValueError('data must be bytes')
+        return self._priv_key.sign(data)
+
+
+class VerifyingKey:
+
+    def __init__(self, pub_key):
+        if not isinstance(pub_key, Ed25519PublicKey):
+            raise ValueError('pub_key must be an Ed25519PublicKey')
+        self._pub_key = pub_key
+
+    @classmethod
+    def from_public_bytes(cls, pub_bytes):
+        if not isinstance(pub_bytes, six.binary_type):
+            raise ValueError('pub_bytes must be bytes')
+        return cls(Ed25519PublicKey.from_public_bytes(pub_bytes))
+
+    def public_bytes(self):
+        return self._pub_key.public_bytes(Encoding.Raw, PublicFormat.Raw)
+
+    def verify(self, signature, data):
+        if not isinstance(signature, six.binary_type):
+            raise ValueError('signature must be bytes')
+
+        if not isinstance(data, six.binary_type):
+            raise ValueError('data must be bytes')
+
+        self._pub_key.verify(signature, data)