Add abstraction for a cryptographic key

Makefile

@@ -11,4 +11,5 @@ lintroll:
 	flake8 $(FILES_TO_LINT)
 
 protobufs:
+	cd libp2p/crypto/pb && protoc --python_out=. crypto.proto
 	cd libp2p/pubsub/pb && protoc --python_out=. rpc.proto

libp2p/crypto/keys.py

@@ -0,0 +1,75 @@
+from abc import ABC, abstractmethod
+from enum import Enum, unique
+
+from .pb import crypto_pb2 as protobuf
+
+
+@unique
+class KeyType(Enum):
+    RSA = 0
+    Ed25519 = 1
+    Secp256k1 = 2
+    ECDSA = 3
+
+
+class Key:
+    """
+    A ``Key`` represents a cryptographic key.
+    """
+
+    @abstractmethod
+    def to_bytes(self) -> bytes:
+        """
+        Returns the byte representation of this key.
+        """
+        ...
+
+    @abstractmethod
+    def get_type(self) -> KeyType:
+        """
+        Returns the ``KeyType`` for ``self``.
+        """
+        ...
+
+
+class PublicKey(ABC, Key):
+    """
+    A ``PublicKey`` represents a cryptographic public key.
+    """
+
+    @abstractmethod
+    def verify(self, data: bytes, signature: bytes) -> bool:
+        """
+        Verify that ``signature`` is the cryptographic signature of the hash of ``data``.
+        """
+        ...
+
+    def serialize_to_protobuf(self) -> protobuf.PublicKey:
+        _type = self.get_type()
+        data = self.to_bytes()
+        protobuf_key = protobuf.PublicKey()
+        protobuf_key.key_type = _type.value
+        protobuf_key.data = data
+        return protobuf_key
+
+
+class PrivateKey(ABC, Key):
+    """
+    A ``PrivateKey`` represents a cryptographic private key.
+    """
+
+    @abstractmethod
+    def sign(self, data: bytes) -> bytes:
+        ...
+
+    @abstractmethod
+    def get_public_key(self) -> PublicKey:
+        ...
+
+    def serialize_to_protobuf(self) -> protobuf.PrivateKey:
+        _type = self.get_type()
+        data = self.to_bytes()
+        protobuf_key = protobuf.PrivateKey()
+        protobuf_key.key_type = _type.value
+        protobuf_key.data = data
+        return protobuf_key

libp2p/crypto/pb/crypto.proto

@@ -0,0 +1,20 @@
+syntax = "proto2";
+
+package crypto.pb;
+
+enum KeyType {
+  RSA = 0;
+  Ed25519 = 1;
+  Secp256k1 = 2;
+  ECDSA = 3;
+}
+
+message PublicKey {
+  required KeyType key_type = 1;
+  required bytes data = 2;
+}
+
+message PrivateKey {
+  required KeyType key_type = 1;
+  required bytes data = 2;
+}

libp2p/crypto/pb/crypto_pb2.py

@@ -0,0 +1,162 @@
+# -*- coding: utf-8 -*-
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: crypto.proto
+
+import sys
+_b=sys.version_info[0]<3 and (lambda x:x) or (lambda x:x.encode('latin1'))
+from google.protobuf.internal import enum_type_wrapper
+from google.protobuf import descriptor as _descriptor
+from google.protobuf import message as _message
+from google.protobuf import reflection as _reflection
+from google.protobuf import symbol_database as _symbol_database
+# @@protoc_insertion_point(imports)
+
+_sym_db = _symbol_database.Default()
+
+
+
+
+DESCRIPTOR = _descriptor.FileDescriptor(
+  name='crypto.proto',
+  package='crypto.pb',
+  syntax='proto2',
+  serialized_options=None,
+  serialized_pb=_b('\n\x0c\x63rypto.proto\x12\tcrypto.pb\"?\n\tPublicKey\x12$\n\x08key_type\x18\x01 \x02(\x0e\x32\x12.crypto.pb.KeyType\x12\x0c\n\x04\x64\x61ta\x18\x02 \x02(\x0c\"@\n\nPrivateKey\x12$\n\x08key_type\x18\x01 \x02(\x0e\x32\x12.crypto.pb.KeyType\x12\x0c\n\x04\x64\x61ta\x18\x02 \x02(\x0c*9\n\x07KeyType\x12\x07\n\x03RSA\x10\x00\x12\x0b\n\x07\x45\x64\x32\x35\x35\x31\x39\x10\x01\x12\r\n\tSecp256k1\x10\x02\x12\t\n\x05\x45\x43\x44SA\x10\x03')
+)
+
+_KEYTYPE = _descriptor.EnumDescriptor(
+  name='KeyType',
+  full_name='crypto.pb.KeyType',
+  filename=None,
+  file=DESCRIPTOR,
+  values=[
+    _descriptor.EnumValueDescriptor(
+      name='RSA', index=0, number=0,
+      serialized_options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='Ed25519', index=1, number=1,
+      serialized_options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='Secp256k1', index=2, number=2,
+      serialized_options=None,
+      type=None),
+    _descriptor.EnumValueDescriptor(
+      name='ECDSA', index=3, number=3,
+      serialized_options=None,
+      type=None),
+  ],
+  containing_type=None,
+  serialized_options=None,
+  serialized_start=158,
+  serialized_end=215,
+)
+_sym_db.RegisterEnumDescriptor(_KEYTYPE)
+
+KeyType = enum_type_wrapper.EnumTypeWrapper(_KEYTYPE)
+RSA = 0
+Ed25519 = 1
+Secp256k1 = 2
+ECDSA = 3
+
+
+
+_PUBLICKEY = _descriptor.Descriptor(
+  name='PublicKey',
+  full_name='crypto.pb.PublicKey',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='key_type', full_name='crypto.pb.PublicKey.key_type', index=0,
+      number=1, type=14, cpp_type=8, label=2,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='data', full_name='crypto.pb.PublicKey.data', index=1,
+      number=2, type=12, cpp_type=9, label=2,
+      has_default_value=False, default_value=_b(""),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  serialized_options=None,
+  is_extendable=False,
+  syntax='proto2',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=27,
+  serialized_end=90,
+)
+
+
+_PRIVATEKEY = _descriptor.Descriptor(
+  name='PrivateKey',
+  full_name='crypto.pb.PrivateKey',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='key_type', full_name='crypto.pb.PrivateKey.key_type', index=0,
+      number=1, type=14, cpp_type=8, label=2,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='data', full_name='crypto.pb.PrivateKey.data', index=1,
+      number=2, type=12, cpp_type=9, label=2,
+      has_default_value=False, default_value=_b(""),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  serialized_options=None,
+  is_extendable=False,
+  syntax='proto2',
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=92,
+  serialized_end=156,
+)
+
+_PUBLICKEY.fields_by_name['key_type'].enum_type = _KEYTYPE
+_PRIVATEKEY.fields_by_name['key_type'].enum_type = _KEYTYPE
+DESCRIPTOR.message_types_by_name['PublicKey'] = _PUBLICKEY
+DESCRIPTOR.message_types_by_name['PrivateKey'] = _PRIVATEKEY
+DESCRIPTOR.enum_types_by_name['KeyType'] = _KEYTYPE
+_sym_db.RegisterFileDescriptor(DESCRIPTOR)
+
+PublicKey = _reflection.GeneratedProtocolMessageType('PublicKey', (_message.Message,), dict(
+  DESCRIPTOR = _PUBLICKEY,
+  __module__ = 'crypto_pb2'
+  # @@protoc_insertion_point(class_scope:crypto.pb.PublicKey)
+  ))
+_sym_db.RegisterMessage(PublicKey)
+
+PrivateKey = _reflection.GeneratedProtocolMessageType('PrivateKey', (_message.Message,), dict(
+  DESCRIPTOR = _PRIVATEKEY,
+  __module__ = 'crypto_pb2'
+  # @@protoc_insertion_point(class_scope:crypto.pb.PrivateKey)
+  ))
+_sym_db.RegisterMessage(PrivateKey)
+
+
+# @@protoc_insertion_point(module_scope)

libp2p/crypto/rsa.py

@@ -0,0 +1,54 @@
+from typing import Tuple
+
+import Crypto.PublicKey.RSA as RSA
+from Crypto.PublicKey.RSA import RsaKey
+
+from libp2p.crypto.keys import KeyType, PrivateKey, PublicKey
+
+
+class RSAPublicKey(PublicKey):
+    def __init__(self, impl: RsaKey) -> None:
+        self.impl = impl
+
+    def to_bytes(self) -> bytes:
+        return self.impl.export_key("DER")
+
+    def get_type(self) -> KeyType:
+        return KeyType.RSA
+
+    def verify(self, data: bytes, signature: bytes) -> bool:
+        raise NotImplementedError
+
+
+class RSAPrivateKey(PrivateKey):
+    def __init__(self, impl: RsaKey) -> None:
+        self.impl = impl
+
+    @classmethod
+    def new(cls, bits: int = 2048, e: int = 65537) -> "RSAPrivateKey":
+        private_key_impl = RSA.generate(bits, e=e)
+        return cls(private_key_impl)
+
+    def to_bytes(self) -> bytes:
+        return self.impl.export_key("DER")
+
+    def get_type(self) -> KeyType:
+        return KeyType.RSA
+
+    def sign(self, data: bytes) -> bytes:
+        raise NotImplementedError
+
+    def get_public_key(self) -> PublicKey:
+        return RSAPublicKey(self.impl.publickey())
+
+
+def create_new_key_pair(
+    bits: int = 2048, e: int = 65537
+) -> Tuple[PrivateKey, PublicKey]:
+    """
+    Returns a new RSA keypair with the requested key size (``bits``) and the given public
+    exponent ``e``. Sane defaults are provided for both values.
+    """
+    private_key = RSAPrivateKey.new(bits, e)
+    public_key = private_key.get_public_key()
+    return private_key, public_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