Merge pull request #254 from ralexstokes/implement-secio

Implement `secio`

Makefile

@@ -1,5 +1,5 @@
 FILES_TO_LINT = libp2p tests examples setup.py
-PB = libp2p/crypto/pb/crypto.proto libp2p/pubsub/pb/rpc.proto libp2p/security/insecure/pb/plaintext.proto
+PB = libp2p/crypto/pb/crypto.proto libp2p/pubsub/pb/rpc.proto libp2p/security/insecure/pb/plaintext.proto libp2p/security/secio/pb/spipe.proto
 PY = $(PB:.proto=_pb2.py)
 PYI = $(PB:.proto=_pb2.pyi)
 

libp2p/__init__.py

@@ -14,6 +14,7 @@ from libp2p.peer.peerstore_interface import IPeerStore
 from libp2p.routing.interfaces import IPeerRouting
 from libp2p.routing.kademlia.kademlia_peer_router import KadmeliaPeerRouter
 from libp2p.security.insecure.transport import PLAINTEXT_PROTOCOL_ID, InsecureTransport
+import libp2p.security.secio.transport as secio
 from libp2p.security.secure_transport_interface import ISecureTransport
 from libp2p.stream_muxer.mplex.mplex import MPLEX_PROTOCOL_ID, Mplex
 from libp2p.stream_muxer.muxer_multistream import MuxerClassType
@@ -98,7 +99,8 @@ def initialize_default_swarm(
 
     muxer_transports_by_protocol = muxer_opt or {MPLEX_PROTOCOL_ID: Mplex}
     security_transports_by_protocol = sec_opt or {
-        TProtocol(PLAINTEXT_PROTOCOL_ID): InsecureTransport(key_pair)
+        TProtocol(PLAINTEXT_PROTOCOL_ID): InsecureTransport(key_pair),
+        TProtocol(secio.ID): secio.Transport(key_pair),
     }
     upgrader = TransportUpgrader(
         security_transports_by_protocol, muxer_transports_by_protocol

libp2p/crypto/authenticated_encryption.py

@@ -0,0 +1,128 @@
+from dataclasses import dataclass
+import hmac
+from typing import Tuple
+
+from Crypto.Cipher import AES
+import Crypto.Util.Counter as Counter
+
+
+class InvalidMACException(Exception):
+    pass
+
+
+@dataclass(frozen=True)
+class EncryptionParameters:
+    cipher_type: str
+    hash_type: str
+    iv: bytes
+    mac_key: bytes
+    cipher_key: bytes
+
+
+class MacAndCipher:
+    def __init__(self, parameters: EncryptionParameters) -> None:
+        self.authenticator = hmac.new(
+            parameters.mac_key, digestmod=parameters.hash_type
+        )
+        iv_bit_size = 8 * len(parameters.iv)
+        cipher = AES.new(
+            parameters.cipher_key,
+            AES.MODE_CTR,
+            counter=Counter.new(
+                iv_bit_size,
+                initial_value=int.from_bytes(parameters.iv, byteorder="big"),
+            ),
+        )
+        self.cipher = cipher
+
+    def encrypt(self, data: bytes) -> bytes:
+        return self.cipher.encrypt(data)
+
+    def authenticate(self, data: bytes) -> bytes:
+        authenticator = self.authenticator.copy()
+        authenticator.update(data)
+        return authenticator.digest()
+
+    def decrypt_if_valid(self, data_with_tag: bytes) -> bytes:
+        tag_position = len(data_with_tag) - self.authenticator.digest_size
+        data = data_with_tag[:tag_position]
+        tag = data_with_tag[tag_position:]
+
+        authenticator = self.authenticator.copy()
+        authenticator.update(data)
+        expected_tag = authenticator.digest()
+
+        if not hmac.compare_digest(tag, expected_tag):
+            raise InvalidMACException(expected_tag, tag)
+
+        return self.cipher.decrypt(data)
+
+
+def initialize_pair(
+    cipher_type: str, hash_type: str, secret: bytes
+) -> Tuple[EncryptionParameters, EncryptionParameters]:
+    """
+    Return a pair of ``Keys`` for use in securing a
+    communications channel with authenticated encryption
+    derived from the ``secret`` and using the
+    requested ``cipher_type`` and ``hash_type``.
+    """
+    if cipher_type != "AES-128":
+        raise NotImplementedError()
+    if hash_type != "SHA256":
+        raise NotImplementedError()
+
+    iv_size = 16
+    cipher_key_size = 16
+    hmac_key_size = 20
+    seed = "key expansion".encode()
+
+    params_size = iv_size + cipher_key_size + hmac_key_size
+    result = bytearray(2 * params_size)
+
+    authenticator = hmac.new(secret, digestmod=hash_type)
+    authenticator.update(seed)
+    tag = authenticator.digest()
+
+    i = 0
+    len_result = 2 * params_size
+    while i < len_result:
+        authenticator = hmac.new(secret, digestmod=hash_type)
+
+        authenticator.update(tag)
+        authenticator.update(seed)
+
+        another_tag = authenticator.digest()
+
+        remaining_bytes = len(another_tag)
+
+        if i + remaining_bytes > len_result:
+            remaining_bytes = len_result - i
+
+        result[i : i + remaining_bytes] = another_tag[0:remaining_bytes]
+
+        i += remaining_bytes
+
+        authenticator = hmac.new(secret, digestmod=hash_type)
+        authenticator.update(tag)
+        tag = authenticator.digest()
+
+    first_half = result[:params_size]
+    second_half = result[params_size:]
+
+    return (
+        EncryptionParameters(
+            cipher_type,
+            hash_type,
+            first_half[0:iv_size],
+            first_half[iv_size + cipher_key_size :],
+            first_half[iv_size : iv_size + cipher_key_size],
+        ),
+        EncryptionParameters(
+            cipher_type,
+            hash_type,
+            second_half[0:iv_size],
+            second_half[iv_size + cipher_key_size :],
+            second_half[iv_size : iv_size + cipher_key_size],
+        ),
+    )

libp2p/crypto/ecc.py

@@ -0,0 +1,56 @@
+from typing import cast
+
+from Crypto.PublicKey import ECC
+from Crypto.PublicKey.ECC import EccKey
+
+from libp2p.crypto.keys import KeyPair, KeyType, PrivateKey, PublicKey
+
+
+class ECCPublicKey(PublicKey):
+    def __init__(self, impl: EccKey) -> None:
+        self.impl = impl
+
+    def to_bytes(self) -> bytes:
+        return cast(bytes, self.impl.export_key(format="DER"))
+
+    @classmethod
+    def from_bytes(cls, data: bytes) -> "ECCPublicKey":
+        public_key_impl = ECC.import_key(data)
+        return cls(public_key_impl)
+
+    def get_type(self) -> KeyType:
+        return KeyType.ECC_P256
+
+    def verify(self, data: bytes, signature: bytes) -> bool:
+        raise NotImplementedError
+
+
+class ECCPrivateKey(PrivateKey):
+    def __init__(self, impl: EccKey) -> None:
+        self.impl = impl
+
+    @classmethod
+    def new(cls, curve: str) -> "ECCPrivateKey":
+        private_key_impl = ECC.generate(curve=curve)
+        return cls(private_key_impl)
+
+    def to_bytes(self) -> bytes:
+        return cast(bytes, self.impl.export_key(format="DER"))
+
+    def get_type(self) -> KeyType:
+        return KeyType.ECC_P256
+
+    def sign(self, data: bytes) -> bytes:
+        raise NotImplementedError
+
+    def get_public_key(self) -> PublicKey:
+        return ECCPublicKey(self.impl.public_key())
+
+
+def create_new_key_pair(curve: str) -> KeyPair:
+    """
+    Return a new ECC keypair with the requested ``curve`` type, e.g. "P-256".
+    """
+    private_key = ECCPrivateKey.new(curve)
+    public_key = private_key.get_public_key()
+    return KeyPair(private_key, public_key)

libp2p/crypto/key_exchange.py

@@ -0,0 +1,29 @@
+from typing import Callable, Tuple, cast
+
+from Crypto.Math.Numbers import Integer
+import Crypto.PublicKey.ECC as ECC
+
+from libp2p.crypto.ecc import ECCPrivateKey, create_new_key_pair
+from libp2p.crypto.keys import PublicKey
+
+SharedKeyGenerator = Callable[[bytes], bytes]
+
+
+def create_ephemeral_key_pair(curve_type: str) -> Tuple[PublicKey, SharedKeyGenerator]:
+    """
+    Facilitates ECDH key exchange.
+    """
+    if curve_type != "P-256":
+        raise NotImplementedError()
+
+    key_pair = create_new_key_pair(curve_type)
+
+    def _key_exchange(serialized_remote_public_key: bytes) -> bytes:
+        remote_public_key = ECC.import_key(serialized_remote_public_key)
+        curve_point = remote_public_key.pointQ
+        private_key = cast(ECCPrivateKey, key_pair.private_key)
+        secret_point = curve_point * private_key.impl.d
+        byte_size = secret_point.size_in_bytes()
+        return cast(Integer, secret_point.x).to_bytes(byte_size)
+
+    return key_pair.public_key, _key_exchange

libp2p/crypto/keys.py

@@ -11,6 +11,7 @@ class KeyType(Enum):
     Ed25519 = 1
     Secp256k1 = 2
     ECDSA = 3
+    ECC_P256 = 4
 
 
 class Key(ABC):
@@ -32,6 +33,11 @@ class Key(ABC):
         """
         ...
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, Key):
+            return NotImplemented
+        return self.to_bytes() == other.to_bytes()
+
 
 class PublicKey(Key):
     """
@@ -60,14 +66,16 @@ class PublicKey(Key):
         """
         return self._serialize_to_protobuf().SerializeToString()
 
+    @classmethod
+    def deserialize_from_protobuf(cls, protobuf_data: bytes) -> protobuf.PublicKey:
+        return protobuf.PublicKey.FromString(protobuf_data)
+
 
 class PrivateKey(Key):
     """
     A ``PrivateKey`` represents a cryptographic private key.
     """
 
-    protobuf_constructor = protobuf.PrivateKey
-
     @abstractmethod
     def sign(self, data: bytes) -> bytes:
         ...
@@ -91,6 +99,10 @@ class PrivateKey(Key):
         """
         return self._serialize_to_protobuf().SerializeToString()
 
+    @classmethod
+    def deserialize_from_protobuf(cls, protobuf_data: bytes) -> protobuf.PrivateKey:
+        return protobuf.PrivateKey.FromString(protobuf_data)
+
 
 @dataclass(frozen=True)
 class KeyPair:

libp2p/crypto/secp256k1.py

@@ -11,15 +11,20 @@ class Secp256k1PublicKey(PublicKey):
         return self.impl.format()
 
     @classmethod
-    def from_bytes(cls, key_bytes: bytes) -> "Secp256k1PublicKey":
+    def from_bytes(cls, data: bytes) -> "Secp256k1PublicKey":
-        secp256k1_pubkey = coincurve.PublicKey(key_bytes)
+        impl = coincurve.PublicKey(data)
-        return cls(secp256k1_pubkey)
+        return cls(impl)
+
+    @classmethod
+    def deserialize(cls, data: bytes) -> "Secp256k1PublicKey":
+        protobuf_key = cls.deserialize_from_protobuf(data)
+        return cls.from_bytes(protobuf_key.data)
 
     def get_type(self) -> KeyType:
         return KeyType.Secp256k1
 
     def verify(self, data: bytes, signature: bytes) -> bool:
-        raise NotImplementedError
+        return self.impl.verify(signature, data)
 
 
 class Secp256k1PrivateKey(PrivateKey):
@@ -34,11 +39,21 @@ class Secp256k1PrivateKey(PrivateKey):
     def to_bytes(self) -> bytes:
         return self.impl.secret
 
+    @classmethod
+    def from_bytes(cls, data: bytes) -> "Secp256k1PrivateKey":
+        impl = coincurve.PrivateKey(data)
+        return cls(impl)
+
+    @classmethod
+    def deserialize(cls, data: bytes) -> "Secp256k1PrivateKey":
+        protobuf_key = cls.deserialize_from_protobuf(data)
+        return cls.from_bytes(protobuf_key.data)
+
     def get_type(self) -> KeyType:
         return KeyType.Secp256k1
 
     def sign(self, data: bytes) -> bytes:
-        raise NotImplementedError
+        return self.impl.sign(data)
 
     def get_public_key(self) -> PublicKey:
         public_key_impl = coincurve.PublicKey.from_secret(self.impl.secret)

libp2p/crypto/serialization.py

@@ -0,0 +1,22 @@
+from libp2p.crypto.keys import KeyType, PrivateKey, PublicKey
+from libp2p.crypto.secp256k1 import Secp256k1PrivateKey, Secp256k1PublicKey
+
+key_type_to_public_key_deserializer = {
+    KeyType.Secp256k1.value: Secp256k1PublicKey.from_bytes
+}
+
+key_type_to_private_key_deserializer = {
+    KeyType.Secp256k1.value: Secp256k1PrivateKey.from_bytes
+}
+
+
+def deserialize_public_key(data: bytes) -> PublicKey:
+    f = PublicKey.deserialize_from_protobuf(data)
+    deserializer = key_type_to_public_key_deserializer[f.key_type]
+    return deserializer(f.data)
+
+
+def deserialize_private_key(data: bytes) -> PrivateKey:
+    f = PrivateKey.deserialize_from_protobuf(data)
+    deserializer = key_type_to_private_key_deserializer[f.key_type]
+    return deserializer(f.data)

libp2p/io/exceptions.py

@@ -0,0 +1,13 @@
+from libp2p.exceptions import BaseLibp2pError
+
+
+class MsgioException(BaseLibp2pError):
+    pass
+
+
+class MissingLengthException(MsgioException):
+    pass
+
+
+class MissingMessageException(MsgioException):
+    pass

libp2p/io/msgio.py

@@ -0,0 +1,24 @@
+from libp2p.network.connection.raw_connection_interface import IRawConnection
+
+from .exceptions import MissingLengthException, MissingMessageException
+
+SIZE_LEN_BYTES = 4
+
+# TODO unify w/ https://github.com/libp2p/py-libp2p/blob/1aed52856f56a4b791696bbcbac31b5f9c2e88c9/libp2p/utils.py#L85-L99  # noqa: E501
+
+
+def encode(msg_bytes: bytes) -> bytes:
+    len_prefix = len(msg_bytes).to_bytes(SIZE_LEN_BYTES, "big")
+    return len_prefix + msg_bytes
+
+
+async def read_next_message(reader: IRawConnection) -> bytes:
+    len_bytes = await reader.read(SIZE_LEN_BYTES)
+    if len(len_bytes) != SIZE_LEN_BYTES:
+        raise MissingLengthException()
+    len_int = int.from_bytes(len_bytes, "big")
+    next_msg = await reader.read(len_int)
+    if len(next_msg) != len_int:
+        # TODO makes sense to keep reading until this condition is true?
+        raise MissingMessageException()
+    return next_msg

libp2p/peer/id.py

@@ -6,6 +6,11 @@ import multihash
 
 from libp2p.crypto.keys import PublicKey
 
+# NOTE: ``FRIENDLY_IDS`` renders a ``str`` representation of ``ID`` as a
+# short string of a prefix of the base58 representation. This feature is primarily
+# intended for debugging, logging, etc.
+FRIENDLY_IDS = True
+
 
 class ID:
     _bytes: bytes
@@ -32,7 +37,13 @@ class ID:
     def __repr__(self) -> str:
         return "<libp2p.peer.id.ID 0x" + self._bytes.hex() + ">"
 
-    __str__ = pretty = to_string = to_base58
+    pretty = to_string = to_base58
+
+    def __str__(self) -> str:
+        if FRIENDLY_IDS:
+            return self.to_string()[2:8]
+        else:
+            return self.to_string()
 
     def __eq__(self, other: object) -> bool:
         if isinstance(other, str):

libp2p/security/base_session.py

@@ -3,7 +3,6 @@ from typing import Optional
 from libp2p.crypto.keys import PrivateKey, PublicKey
 from libp2p.network.connection.raw_connection_interface import IRawConnection
 from libp2p.peer.id import ID
-from libp2p.security.base_transport import BaseSecureTransport
 from libp2p.security.secure_conn_interface import ISecureConn
 
 
@@ -20,14 +19,18 @@ class BaseSession(ISecureConn):
     remote_permanent_pubkey: PublicKey
 
     def __init__(
-        self, transport: BaseSecureTransport, conn: IRawConnection, peer_id: ID
+        self,
+        local_peer: ID,
+        local_private_key: PrivateKey,
+        conn: IRawConnection,
+        peer_id: Optional[ID] = None,
     ) -> None:
-        self.local_peer = transport.local_peer
+        self.local_peer = local_peer
-        self.local_private_key = transport.local_private_key
+        self.local_private_key = local_private_key
-        self.conn = conn
         self.remote_peer_id = peer_id
         self.remote_permanent_pubkey = None
 
+        self.conn = conn
         self.initiator = self.conn.initiator
 
     async def write(self, data: bytes) -> None:

libp2p/security/base_transport.py

@@ -1,14 +1,30 @@
+import secrets
+from typing import Callable
+
 from libp2p.crypto.keys import KeyPair
 from libp2p.peer.id import ID
 from libp2p.security.secure_transport_interface import ISecureTransport
 
 
+def default_secure_bytes_provider(n: int) -> bytes:
+    return secrets.token_bytes(n)
+
+
 class BaseSecureTransport(ISecureTransport):
     """
     ``BaseSecureTransport`` is not fully instantiated from its abstract classes as it
     is only meant to be used in clases that derive from it.
+
+    Clients can provide a strategy to get cryptographically secure bytes of a given length.
+    A default implementation is provided using the ``secrets`` module from the
+    standard library.
     """
 
-    def __init__(self, local_key_pair: KeyPair) -> None:
+    def __init__(
+        self,
+        local_key_pair: KeyPair,
+        secure_bytes_provider: Callable[[int], bytes] = default_secure_bytes_provider,
+    ) -> None:
         self.local_private_key = local_key_pair.private_key
         self.local_peer = ID.from_pubkey(local_key_pair.public_key)
+        self.secure_bytes_provider = secure_bytes_provider

libp2p/security/insecure/transport.py

@@ -76,7 +76,7 @@ class InsecureTransport(BaseSecureTransport):
         for an inbound connection (i.e. we are not the initiator)
         :return: secure connection object (that implements secure_conn_interface)
         """
-        session = InsecureSession(self, conn, ID(b""))
+        session = InsecureSession(self.local_peer, self.local_private_key, conn)
         await session.run_handshake()
         return session
 
@@ -86,7 +86,9 @@ class InsecureTransport(BaseSecureTransport):
         for an inbound connection (i.e. we are the initiator)
         :return: secure connection object (that implements secure_conn_interface)
         """
-        session = InsecureSession(self, conn, peer_id)
+        session = InsecureSession(
+            self.local_peer, self.local_private_key, conn, peer_id
+        )
         await session.run_handshake()
         return session
 

libp2p/security/secio/exceptions.py

@@ -0,0 +1,27 @@
+class SecioException(Exception):
+    pass
+
+
+class SelfEncryption(SecioException):
+    """
+    Raised to indicate that a host is attempting to encrypt communications
+    with itself.
+    """
+
+    pass
+
+
+class PeerMismatchException(SecioException):
+    pass
+
+
+class InvalidSignatureOnExchange(SecioException):
+    pass
+
+
+class HandshakeFailed(SecioException):
+    pass
+
+
+class IncompatibleChoices(SecioException):
+    pass

libp2p/security/secio/pb/spipe.proto

@@ -0,0 +1,16 @@
+syntax = "proto2";
+
+package spipe.pb;
+
+message Propose {
+  optional bytes rand = 1;
+  optional bytes public_key = 2;
+  optional string exchanges = 3;
+  optional string ciphers = 4;
+  optional string hashes = 5;
+}
+
+message Exchange {
+  optional bytes ephemeral_public_key = 1;
+  optional bytes signature = 2;
+}

libp2p/security/secio/pb/spipe_pb2.py

@@ -0,0 +1,144 @@
+# -*- coding: utf-8 -*-
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: spipe.proto
+
+import sys
+_b=sys.version_info[0]<3 and (lambda x:x) or (lambda x:x.encode('latin1'))
+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='spipe.proto',
+  package='spipe.pb',
+  syntax='proto2',
+  serialized_options=None,
+  serialized_pb=_b('\n\x0bspipe.proto\x12\x08spipe.pb\"_\n\x07Propose\x12\x0c\n\x04rand\x18\x01 \x01(\x0c\x12\x12\n\npublic_key\x18\x02 \x01(\x0c\x12\x11\n\texchanges\x18\x03 \x01(\t\x12\x0f\n\x07\x63iphers\x18\x04 \x01(\t\x12\x0e\n\x06hashes\x18\x05 \x01(\t\";\n\x08\x45xchange\x12\x1c\n\x14\x65phemeral_public_key\x18\x01 \x01(\x0c\x12\x11\n\tsignature\x18\x02 \x01(\x0c')
+)
+
+
+
+
+_PROPOSE = _descriptor.Descriptor(
+  name='Propose',
+  full_name='spipe.pb.Propose',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='rand', full_name='spipe.pb.Propose.rand', index=0,
+      number=1, type=12, cpp_type=9, label=1,
+      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),
+    _descriptor.FieldDescriptor(
+      name='public_key', full_name='spipe.pb.Propose.public_key', index=1,
+      number=2, type=12, cpp_type=9, label=1,
+      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),
+    _descriptor.FieldDescriptor(
+      name='exchanges', full_name='spipe.pb.Propose.exchanges', index=2,
+      number=3, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='ciphers', full_name='spipe.pb.Propose.ciphers', index=3,
+      number=4, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      serialized_options=None, file=DESCRIPTOR),
+    _descriptor.FieldDescriptor(
+      name='hashes', full_name='spipe.pb.Propose.hashes', index=4,
+      number=5, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      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=25,
+  serialized_end=120,
+)
+
+
+_EXCHANGE = _descriptor.Descriptor(
+  name='Exchange',
+  full_name='spipe.pb.Exchange',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='ephemeral_public_key', full_name='spipe.pb.Exchange.ephemeral_public_key', index=0,
+      number=1, type=12, cpp_type=9, label=1,
+      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),
+    _descriptor.FieldDescriptor(
+      name='signature', full_name='spipe.pb.Exchange.signature', index=1,
+      number=2, type=12, cpp_type=9, label=1,
+      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=122,
+  serialized_end=181,
+)
+
+DESCRIPTOR.message_types_by_name['Propose'] = _PROPOSE
+DESCRIPTOR.message_types_by_name['Exchange'] = _EXCHANGE
+_sym_db.RegisterFileDescriptor(DESCRIPTOR)
+
+Propose = _reflection.GeneratedProtocolMessageType('Propose', (_message.Message,), dict(
+  DESCRIPTOR = _PROPOSE,
+  __module__ = 'spipe_pb2'
+  # @@protoc_insertion_point(class_scope:spipe.pb.Propose)
+  ))
+_sym_db.RegisterMessage(Propose)
+
+Exchange = _reflection.GeneratedProtocolMessageType('Exchange', (_message.Message,), dict(
+  DESCRIPTOR = _EXCHANGE,
+  __module__ = 'spipe_pb2'
+  # @@protoc_insertion_point(class_scope:spipe.pb.Exchange)
+  ))
+_sym_db.RegisterMessage(Exchange)
+
+
+# @@protoc_insertion_point(module_scope)

libp2p/security/secio/pb/spipe_pb2.pyi

@@ -0,0 +1,67 @@
+# @generated by generate_proto_mypy_stubs.py.  Do not edit!
+import sys
+from google.protobuf.descriptor import (
+    Descriptor as google___protobuf___descriptor___Descriptor,
+)
+
+from google.protobuf.message import (
+    Message as google___protobuf___message___Message,
+)
+
+from typing import (
+    Optional as typing___Optional,
+    Text as typing___Text,
+)
+
+from typing_extensions import (
+    Literal as typing_extensions___Literal,
+)
+
+
+class Propose(google___protobuf___message___Message):
+    DESCRIPTOR: google___protobuf___descriptor___Descriptor = ...
+    rand = ... # type: bytes
+    public_key = ... # type: bytes
+    exchanges = ... # type: typing___Text
+    ciphers = ... # type: typing___Text
+    hashes = ... # type: typing___Text
+
+    def __init__(self,
+        *,
+        rand : typing___Optional[bytes] = None,
+        public_key : typing___Optional[bytes] = None,
+        exchanges : typing___Optional[typing___Text] = None,
+        ciphers : typing___Optional[typing___Text] = None,
+        hashes : typing___Optional[typing___Text] = None,
+        ) -> None: ...
+    @classmethod
+    def FromString(cls, s: bytes) -> Propose: ...
+    def MergeFrom(self, other_msg: google___protobuf___message___Message) -> None: ...
+    def CopyFrom(self, other_msg: google___protobuf___message___Message) -> None: ...
+    if sys.version_info >= (3,):
+        def HasField(self, field_name: typing_extensions___Literal[u"ciphers",u"exchanges",u"hashes",u"public_key",u"rand"]) -> bool: ...
+        def ClearField(self, field_name: typing_extensions___Literal[u"ciphers",u"exchanges",u"hashes",u"public_key",u"rand"]) -> None: ...
+    else:
+        def HasField(self, field_name: typing_extensions___Literal[u"ciphers",b"ciphers",u"exchanges",b"exchanges",u"hashes",b"hashes",u"public_key",b"public_key",u"rand",b"rand"]) -> bool: ...
+        def ClearField(self, field_name: typing_extensions___Literal[u"ciphers",b"ciphers",u"exchanges",b"exchanges",u"hashes",b"hashes",u"public_key",b"public_key",u"rand",b"rand"]) -> None: ...
+
+class Exchange(google___protobuf___message___Message):
+    DESCRIPTOR: google___protobuf___descriptor___Descriptor = ...
+    ephemeral_public_key = ... # type: bytes
+    signature = ... # type: bytes
+
+    def __init__(self,
+        *,
+        ephemeral_public_key : typing___Optional[bytes] = None,
+        signature : typing___Optional[bytes] = None,
+        ) -> None: ...
+    @classmethod
+    def FromString(cls, s: bytes) -> Exchange: ...
+    def MergeFrom(self, other_msg: google___protobuf___message___Message) -> None: ...
+    def CopyFrom(self, other_msg: google___protobuf___message___Message) -> None: ...
+    if sys.version_info >= (3,):
+        def HasField(self, field_name: typing_extensions___Literal[u"ephemeral_public_key",u"signature"]) -> bool: ...
+        def ClearField(self, field_name: typing_extensions___Literal[u"ephemeral_public_key",u"signature"]) -> None: ...
+    else:
+        def HasField(self, field_name: typing_extensions___Literal[u"ephemeral_public_key",b"ephemeral_public_key",u"signature",b"signature"]) -> bool: ...
+        def ClearField(self, field_name: typing_extensions___Literal[u"ephemeral_public_key",b"ephemeral_public_key",u"signature",b"signature"]) -> None: ...

libp2p/security/secio/transport.py

@@ -0,0 +1,403 @@
+from dataclasses import dataclass
+from typing import Optional, Tuple
+
+import multihash
+
+from libp2p.crypto.authenticated_encryption import (
+    EncryptionParameters as AuthenticatedEncryptionParameters,
+)
+from libp2p.crypto.authenticated_encryption import (
+    initialize_pair as initialize_pair_for_encryption,
+)
+from libp2p.crypto.authenticated_encryption import MacAndCipher as Encrypter
+from libp2p.crypto.ecc import ECCPublicKey
+from libp2p.crypto.key_exchange import create_ephemeral_key_pair
+from libp2p.crypto.keys import PrivateKey, PublicKey
+from libp2p.crypto.serialization import deserialize_public_key
+from libp2p.io.msgio import encode as encode_message
+from libp2p.io.msgio import read_next_message
+from libp2p.network.connection.raw_connection_interface import IRawConnection
+from libp2p.peer.id import ID as PeerID
+from libp2p.security.base_session import BaseSession
+from libp2p.security.base_transport import BaseSecureTransport
+from libp2p.security.secure_conn_interface import ISecureConn
+
+from .exceptions import (
+    HandshakeFailed,
+    IncompatibleChoices,
+    InvalidSignatureOnExchange,
+    PeerMismatchException,
+    SecioException,
+    SelfEncryption,
+)
+from .pb.spipe_pb2 import Exchange, Propose
+
+ID = "/secio/1.0.0"
+
+NONCE_SIZE = 16  # bytes
+
+# NOTE: the following is only a subset of allowable parameters according to the
+# `secio` specification.
+DEFAULT_SUPPORTED_EXCHANGES = "P-256"
+DEFAULT_SUPPORTED_CIPHERS = "AES-128"
+DEFAULT_SUPPORTED_HASHES = "SHA256"
+
+
+class SecureSession(BaseSession):
+    def __init__(
+        self,
+        local_peer: PeerID,
+        local_private_key: PrivateKey,
+        local_encryption_parameters: AuthenticatedEncryptionParameters,
+        remote_peer: PeerID,
+        remote_encryption_parameters: AuthenticatedEncryptionParameters,
+        conn: IRawConnection,
+    ) -> None:
+        super().__init__(local_peer, local_private_key, conn, remote_peer)
+
+        self.local_encryption_parameters = local_encryption_parameters
+        self.remote_encryption_parameters = remote_encryption_parameters
+        self._initialize_authenticated_encryption_for_local_peer()
+        self._initialize_authenticated_encryption_for_remote_peer()
+
+    def _initialize_authenticated_encryption_for_local_peer(self) -> None:
+        self.local_encrypter = Encrypter(self.local_encryption_parameters)
+
+    def _initialize_authenticated_encryption_for_remote_peer(self) -> None:
+        self.remote_encrypter = Encrypter(self.remote_encryption_parameters)
+
+    async def read(self, n: int = -1) -> bytes:
+        return await self._read_msg()
+
+    async def _read_msg(self) -> bytes:
+        # TODO do we need to serialize reads?
+        msg = await read_next_message(self.conn)
+        return self.remote_encrypter.decrypt_if_valid(msg)
+
+    async def write(self, data: bytes) -> None:
+        await self._write_msg(data)
+
+    async def _write_msg(self, data: bytes) -> None:
+        # TODO do we need to serialize writes?
+        encrypted_data = self.local_encrypter.encrypt(data)
+        tag = self.local_encrypter.authenticate(encrypted_data)
+        msg = encode_message(encrypted_data + tag)
+        await self.conn.write(msg)
+
+
+@dataclass(frozen=True)
+class Proposal:
+    """
+    A ``Proposal`` represents the set of session parameters one peer in a pair of
+    peers attempting to negotiate a `secio` channel prefers.
+    """
+
+    nonce: bytes
+    public_key: PublicKey
+    exchanges: str = DEFAULT_SUPPORTED_EXCHANGES  # comma separated list
+    ciphers: str = DEFAULT_SUPPORTED_CIPHERS  # comma separated list
+    hashes: str = DEFAULT_SUPPORTED_HASHES  # comma separated list
+
+    def serialize(self) -> bytes:
+        protobuf = Propose(
+            rand=self.nonce,
+            public_key=self.public_key.serialize(),
+            exchanges=self.exchanges,
+            ciphers=self.ciphers,
+            hashes=self.hashes,
+        )
+        return protobuf.SerializeToString()
+
+    @classmethod
+    def deserialize(cls, protobuf_bytes: bytes) -> "Proposal":
+        protobuf = Propose.FromString(protobuf_bytes)
+
+        nonce = protobuf.rand
+        public_key_protobuf_bytes = protobuf.public_key
+        public_key = deserialize_public_key(public_key_protobuf_bytes)
+        exchanges = protobuf.exchanges
+        ciphers = protobuf.ciphers
+        hashes = protobuf.hashes
+
+        return cls(nonce, public_key, exchanges, ciphers, hashes)
+
+    def calculate_peer_id(self) -> PeerID:
+        return PeerID.from_pubkey(self.public_key)
+
+
+@dataclass
+class EncryptionParameters:
+    permanent_public_key: PublicKey
+
+    curve_type: str
+    cipher_type: str
+    hash_type: str
+
+    ephemeral_public_key: PublicKey
+
+    def __init__(self) -> None:
+        pass
+
+
+@dataclass
+class SessionParameters:
+    local_peer: PeerID
+    local_encryption_parameters: EncryptionParameters
+
+    remote_peer: PeerID
+    remote_encryption_parameters: EncryptionParameters
+
+    # order is a comparator used to break the symmetry b/t each pair of peers
+    order: int
+    shared_key: bytes
+
+    def __init__(self) -> None:
+        pass
+
+
+async def _response_to_msg(conn: IRawConnection, msg: bytes) -> bytes:
+    await conn.write(encode_message(msg))
+    return await read_next_message(conn)
+
+
+def _mk_multihash_sha256(data: bytes) -> bytes:
+    return multihash.digest(data, "sha2-256")
+
+
+def _mk_score(public_key: PublicKey, nonce: bytes) -> bytes:
+    return _mk_multihash_sha256(public_key.serialize() + nonce)
+
+
+def _select_parameter_from_order(
+    order: int, supported_parameters: str, available_parameters: str
+) -> str:
+    if order < 0:
+        first_choices = available_parameters.split(",")
+        second_choices = supported_parameters.split(",")
+    elif order > 0:
+        first_choices = supported_parameters.split(",")
+        second_choices = available_parameters.split(",")
+    else:
+        return supported_parameters.split(",")[0]
+
+    for first, second in zip(first_choices, second_choices):
+        if first == second:
+            return first
+    raise IncompatibleChoices()
+
+
+def _select_encryption_parameters(
+    local_proposal: Proposal, remote_proposal: Proposal
+) -> Tuple[str, str, str, int]:
+    first_score = _mk_score(remote_proposal.public_key, local_proposal.nonce)
+    second_score = _mk_score(local_proposal.public_key, remote_proposal.nonce)
+
+    order = 0
+    if first_score < second_score:
+        order = -1
+    elif second_score < first_score:
+        order = 1
+
+    if order == 0:
+        raise SelfEncryption()
+
+    return (
+        _select_parameter_from_order(
+            order, DEFAULT_SUPPORTED_EXCHANGES, remote_proposal.exchanges
+        ),
+        _select_parameter_from_order(
+            order, DEFAULT_SUPPORTED_CIPHERS, remote_proposal.ciphers
+        ),
+        _select_parameter_from_order(
+            order, DEFAULT_SUPPORTED_HASHES, remote_proposal.hashes
+        ),
+        order,
+    )
+
+
+async def _establish_session_parameters(
+    local_peer: PeerID,
+    local_private_key: PrivateKey,
+    remote_peer: Optional[PeerID],
+    conn: IRawConnection,
+    nonce: bytes,
+) -> Tuple[SessionParameters, bytes]:
+    # establish shared encryption parameters
+    session_parameters = SessionParameters()
+    session_parameters.local_peer = local_peer
+
+    local_encryption_parameters = EncryptionParameters()
+    session_parameters.local_encryption_parameters = local_encryption_parameters
+
+    local_public_key = local_private_key.get_public_key()
+    local_encryption_parameters.permanent_public_key = local_public_key
+
+    local_proposal = Proposal(nonce, local_public_key)
+    serialized_local_proposal = local_proposal.serialize()
+    serialized_remote_proposal = await _response_to_msg(conn, serialized_local_proposal)
+
+    remote_encryption_parameters = EncryptionParameters()
+    session_parameters.remote_encryption_parameters = remote_encryption_parameters
+    remote_proposal = Proposal.deserialize(serialized_remote_proposal)
+    remote_encryption_parameters.permanent_public_key = remote_proposal.public_key
+
+    remote_peer_from_proposal = remote_proposal.calculate_peer_id()
+    if not remote_peer:
+        remote_peer = remote_peer_from_proposal
+    elif remote_peer != remote_peer_from_proposal:
+        raise PeerMismatchException()
+    session_parameters.remote_peer = remote_peer
+
+    curve_param, cipher_param, hash_param, order = _select_encryption_parameters(
+        local_proposal, remote_proposal
+    )
+    local_encryption_parameters.curve_type = curve_param
+    local_encryption_parameters.cipher_type = cipher_param
+    local_encryption_parameters.hash_type = hash_param
+    remote_encryption_parameters.curve_type = curve_param
+    remote_encryption_parameters.cipher_type = cipher_param
+    remote_encryption_parameters.hash_type = hash_param
+    session_parameters.order = order
+
+    # exchange ephemeral pub keys
+    local_ephemeral_public_key, shared_key_generator = create_ephemeral_key_pair(
+        curve_param
+    )
+    local_encryption_parameters.ephemeral_public_key = local_ephemeral_public_key
+    local_selection = (
+        serialized_local_proposal
+        + serialized_remote_proposal
+        + local_ephemeral_public_key.to_bytes()
+    )
+    exchange_signature = local_private_key.sign(local_selection)
+    local_exchange = Exchange(
+        ephemeral_public_key=local_ephemeral_public_key.to_bytes(),
+        signature=exchange_signature,
+    )
+
+    serialized_local_exchange = local_exchange.SerializeToString()
+    serialized_remote_exchange = await _response_to_msg(conn, serialized_local_exchange)
+
+    remote_exchange = Exchange()
+    remote_exchange.ParseFromString(serialized_remote_exchange)
+
+    remote_ephemeral_public_key_bytes = remote_exchange.ephemeral_public_key
+    remote_ephemeral_public_key = ECCPublicKey.from_bytes(
+        remote_ephemeral_public_key_bytes
+    )
+    remote_encryption_parameters.ephemeral_public_key = remote_ephemeral_public_key
+    remote_selection = (
+        serialized_remote_proposal
+        + serialized_local_proposal
+        + remote_ephemeral_public_key_bytes
+    )
+    valid_signature = remote_encryption_parameters.permanent_public_key.verify(
+        remote_selection, remote_exchange.signature
+    )
+    if not valid_signature:
+        raise InvalidSignatureOnExchange()
+
+    shared_key = shared_key_generator(remote_ephemeral_public_key_bytes)
+    session_parameters.shared_key = shared_key
+
+    return session_parameters, remote_proposal.nonce
+
+
+def _mk_session_from(
+    local_private_key: PrivateKey,
+    session_parameters: SessionParameters,
+    conn: IRawConnection,
+) -> SecureSession:
+    key_set1, key_set2 = initialize_pair_for_encryption(
+        session_parameters.local_encryption_parameters.cipher_type,
+        session_parameters.local_encryption_parameters.hash_type,
+        session_parameters.shared_key,
+    )
+
+    if session_parameters.order < 0:
+        key_set1, key_set2 = key_set2, key_set1
+
+    session = SecureSession(
+        session_parameters.local_peer,
+        local_private_key,
+        key_set1,
+        session_parameters.remote_peer,
+        key_set2,
+        conn,
+    )
+    return session
+
+
+async def _finish_handshake(session: ISecureConn, remote_nonce: bytes) -> bytes:
+    await session.write(remote_nonce)
+    return await session.read()
+
+
+async def create_secure_session(
+    local_nonce: bytes,
+    local_peer: PeerID,
+    local_private_key: PrivateKey,
+    conn: IRawConnection,
+    remote_peer: PeerID = None,
+) -> ISecureConn:
+    """
+    Attempt the initial `secio` handshake with the remote peer.
+    If successful, return an object that provides secure communication to the
+    ``remote_peer``.
+    """
+    try:
+        session_parameters, remote_nonce = await _establish_session_parameters(
+            local_peer, local_private_key, remote_peer, conn, local_nonce
+        )
+    except SecioException as e:
+        await conn.close()
+        raise e
+
+    session = _mk_session_from(local_private_key, session_parameters, conn)
+
+    received_nonce = await _finish_handshake(session, remote_nonce)
+    if received_nonce != local_nonce:
+        await conn.close()
+        raise HandshakeFailed()
+
+    return session
+
+
+class Transport(BaseSecureTransport):
+    """
+    ``Transport`` provides a security upgrader for a ``IRawConnection``,
+    following the `secio` protocol defined in the libp2p specs.
+    """
+
+    def get_nonce(self) -> bytes:
+        return self.secure_bytes_provider(NONCE_SIZE)
+
+    async def secure_inbound(self, conn: IRawConnection) -> ISecureConn:
+        """
+        Secure the connection, either locally or by communicating with opposing node via conn,
+        for an inbound connection (i.e. we are not the initiator)
+        :return: secure connection object (that implements secure_conn_interface)
+        """
+        local_nonce = self.get_nonce()
+        local_peer = self.local_peer
+        local_private_key = self.local_private_key
+
+        return await create_secure_session(
+            local_nonce, local_peer, local_private_key, conn
+        )
+
+    async def secure_outbound(
+        self, conn: IRawConnection, peer_id: PeerID
+    ) -> ISecureConn:
+        """
+        Secure the connection, either locally or by communicating with opposing node via conn,
+        for an inbound connection (i.e. we are the initiator)
+        :return: secure connection object (that implements secure_conn_interface)
+        """
+        local_nonce = self.get_nonce()
+        local_peer = self.local_peer
+        local_private_key = self.local_private_key
+
+        return await create_secure_session(
+            local_nonce, local_peer, local_private_key, conn, peer_id
+        )

libp2p/security/simple/transport.py

@@ -0,0 +1,79 @@
+import asyncio
+
+from libp2p.crypto.keys import KeyPair
+from libp2p.network.connection.raw_connection_interface import IRawConnection
+from libp2p.peer.id import ID
+from libp2p.security.base_transport import BaseSecureTransport
+from libp2p.security.insecure.transport import InsecureSession
+from libp2p.security.secure_conn_interface import ISecureConn
+from libp2p.transport.exceptions import SecurityUpgradeFailure
+from libp2p.utils import encode_fixedint_prefixed, read_fixedint_prefixed
+
+
+class SimpleSecurityTransport(BaseSecureTransport):
+    key_phrase: str
+
+    def __init__(self, local_key_pair: KeyPair, key_phrase: str) -> None:
+        super().__init__(local_key_pair)
+        self.key_phrase = key_phrase
+
+    async def secure_inbound(self, conn: IRawConnection) -> ISecureConn:
+        """
+        Secure the connection, either locally or by communicating with opposing node via conn,
+        for an inbound connection (i.e. we are not the initiator)
+        :return: secure connection object (that implements secure_conn_interface)
+        """
+        await conn.write(encode_fixedint_prefixed(self.key_phrase.encode()))
+        incoming = (await read_fixedint_prefixed(conn)).decode()
+
+        if incoming != self.key_phrase:
+            raise SecurityUpgradeFailure(
+                "Key phrase differed between nodes. Expected " + self.key_phrase
+            )
+
+        session = InsecureSession(
+            self.local_peer, self.local_private_key, conn, ID(b"")
+        )
+        # NOTE: Here we calls `run_handshake` for both sides to exchange their public keys and
+        #   peer ids, otherwise tests fail. However, it seems pretty weird that
+        #   `SimpleSecurityTransport` sends peer id through `Insecure`.
+        await session.run_handshake()
+        # NOTE: this is abusing the abstraction we have here
+        # but this code may be deprecated soon and this exists
+        # mainly to satisfy a test that will go along w/ it
+        # FIXME: Enable type check back when we can deprecate the simple transport.
+        session.key_phrase = self.key_phrase  # type: ignore
+        return session
+
+    async def secure_outbound(self, conn: IRawConnection, peer_id: ID) -> ISecureConn:
+        """
+        Secure the connection, either locally or by communicating with opposing node via conn,
+        for an inbound connection (i.e. we are the initiator)
+        :return: secure connection object (that implements secure_conn_interface)
+        """
+        await conn.write(encode_fixedint_prefixed(self.key_phrase.encode()))
+        incoming = (await read_fixedint_prefixed(conn)).decode()
+
+        # Force context switch, as this security transport is built for testing locally
+        # in a single event loop
+        await asyncio.sleep(0)
+
+        if incoming != self.key_phrase:
+            raise SecurityUpgradeFailure(
+                "Key phrase differed between nodes. Expected " + self.key_phrase
+            )
+
+        session = InsecureSession(
+            self.local_peer, self.local_private_key, conn, peer_id
+        )
+
+        # NOTE: Here we calls `run_handshake` for both sides to exchange their public keys and
+        #   peer ids, otherwise tests fail. However, it seems pretty weird that
+        #   `SimpleSecurityTransport` sends peer id through `Insecure`.
+        await session.run_handshake()
+        # NOTE: this is abusing the abstraction we have here
+        # but this code may be deprecated soon and this exists
+        # mainly to satisfy a test that will go along w/ it
+        # FIXME: Enable type check back when we can deprecate the simple transport.
+        session.key_phrase = self.key_phrase  # type: ignore
+        return session

tests/crypto/test_secp256k1.py

@@ -0,0 +1,22 @@
+from libp2p.crypto.secp256k1 import create_new_key_pair
+from libp2p.crypto.serialization import deserialize_private_key, deserialize_public_key
+
+
+def test_public_key_serialize_deserialize_round_trip():
+    key_pair = create_new_key_pair()
+    public_key = key_pair.public_key
+
+    public_key_bytes = public_key.serialize()
+    another_public_key = deserialize_public_key(public_key_bytes)
+
+    assert public_key == another_public_key
+
+
+def test_private_key_serialize_deserialize_round_trip():
+    key_pair = create_new_key_pair()
+    private_key = key_pair.private_key
+
+    private_key_bytes = private_key.serialize()
+    another_private_key = deserialize_private_key(private_key_bytes)
+
+    assert private_key == another_private_key

tests/peer/test_peerid.py

@@ -4,10 +4,14 @@ import base58
 import multihash
 
 from libp2p.crypto.rsa import create_new_key_pair
+import libp2p.peer.id as PeerID
 from libp2p.peer.id import ID
 
 ALPHABETS = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"
 
+# ensure we are not in "debug" mode for the following tests
+PeerID.FRIENDLY_IDS = False
+
 
 def test_eq_impl_for_bytes():
     random_id_string = ""

tests/security/test_secio.py

@@ -0,0 +1,101 @@
+import asyncio
+
+import pytest
+
+from libp2p.crypto.secp256k1 import create_new_key_pair
+from libp2p.network.connection.raw_connection_interface import IRawConnection
+from libp2p.peer.id import ID
+from libp2p.security.secio.transport import NONCE_SIZE, create_secure_session
+
+
+class InMemoryConnection(IRawConnection):
+    def __init__(self, peer, initiator=False):
+        self.peer = peer
+        self.recv_queue = asyncio.Queue()
+        self.send_queue = asyncio.Queue()
+        self.initiator = initiator
+
+        self.current_msg = None
+        self.current_position = 0
+
+        self.closed = False
+
+    async def write(self, data: bytes) -> None:
+        if self.closed:
+            raise Exception("InMemoryConnection is closed for writing")
+
+        await self.send_queue.put(data)
+
+    async def read(self, n: int = -1) -> bytes:
+        """
+        NOTE: have to buffer the current message and juggle packets
+        off the recv queue to satisfy the semantics of this function.
+        """
+        if self.closed:
+            raise Exception("InMemoryConnection is closed for reading")
+
+        if not self.current_msg:
+            self.current_msg = await self.recv_queue.get()
+            self.current_position = 0
+
+        if n < 0:
+            msg = self.current_msg
+            self.current_msg = None
+            return msg
+
+        next_msg = self.current_msg[self.current_position : self.current_position + n]
+        self.current_position += n
+        if self.current_position == len(self.current_msg):
+            self.current_msg = None
+        return next_msg
+
+    async def close(self) -> None:
+        self.closed = True
+
+
+async def create_pipe(local_conn, remote_conn):
+    try:
+        while True:
+            next_msg = await local_conn.send_queue.get()
+            await remote_conn.recv_queue.put(next_msg)
+    except asyncio.CancelledError:
+        return
+
+
+@pytest.mark.asyncio
+async def test_create_secure_session():
+    local_nonce = b"\x01" * NONCE_SIZE
+    local_key_pair = create_new_key_pair(b"a")
+    local_peer = ID.from_pubkey(local_key_pair.public_key)
+
+    remote_nonce = b"\x02" * NONCE_SIZE
+    remote_key_pair = create_new_key_pair(b"b")
+    remote_peer = ID.from_pubkey(remote_key_pair.public_key)
+
+    local_conn = InMemoryConnection(local_peer, initiator=True)
+    remote_conn = InMemoryConnection(remote_peer)
+
+    local_pipe_task = asyncio.create_task(create_pipe(local_conn, remote_conn))
+    remote_pipe_task = asyncio.create_task(create_pipe(remote_conn, local_conn))
+
+    local_session_builder = create_secure_session(
+        local_nonce, local_peer, local_key_pair.private_key, local_conn, remote_peer
+    )
+    remote_session_builder = create_secure_session(
+        remote_nonce, remote_peer, remote_key_pair.private_key, remote_conn
+    )
+    local_secure_conn, remote_secure_conn = await asyncio.gather(
+        local_session_builder, remote_session_builder
+    )
+
+    msg = b"abc"
+    await local_secure_conn.write(msg)
+    received_msg = await remote_secure_conn.read()
+    assert received_msg == msg
+
+    await asyncio.gather(local_secure_conn.close(), remote_secure_conn.close())
+
+    local_pipe_task.cancel()
+    remote_pipe_task.cancel()
+    await local_pipe_task
+    await remote_pipe_task