Split the package into a shared library and separate per-device packages

libagent/device/__init__.py

@@ -0,0 +1,3 @@
+"""Cryptographic hardware device management."""
+
+from . import interface

libagent/device/interface.py

@@ -0,0 +1,135 @@
+"""Device abstraction layer."""
+
+import hashlib
+import io
+import logging
+import re
+import struct
+
+from .. import formats, util
+
+log = logging.getLogger(__name__)
+
+_identity_regexp = re.compile(''.join([
+    '^'
+    r'(?:(?P<proto>.*)://)?',
+    r'(?:(?P<user>.*)@)?',
+    r'(?P<host>.*?)',
+    r'(?::(?P<port>\w*))?',
+    r'(?P<path>/.*)?',
+    '$'
+]))
+
+
+def string_to_identity(identity_str):
+    """Parse string into Identity dictionary."""
+    m = _identity_regexp.match(identity_str)
+    result = m.groupdict()
+    log.debug('parsed identity: %s', result)
+    return {k: v for k, v in result.items() if v}
+
+
+def identity_to_string(identity_dict):
+    """Dump Identity dictionary into its string representation."""
+    result = []
+    if identity_dict.get('proto'):
+        result.append(identity_dict['proto'] + '://')
+    if identity_dict.get('user'):
+        result.append(identity_dict['user'] + '@')
+    result.append(identity_dict['host'])
+    if identity_dict.get('port'):
+        result.append(':' + identity_dict['port'])
+    if identity_dict.get('path'):
+        result.append(identity_dict['path'])
+    log.debug('identity parts: %s', result)
+    return ''.join(result)
+
+
+class Error(Exception):
+    """Device-related error."""
+
+
+class NotFoundError(Error):
+    """Device could not be found."""
+
+
+class DeviceError(Error):
+    """Error during device operation."""
+
+
+class Identity(object):
+    """Represent SLIP-0013 identity, together with a elliptic curve choice."""
+
+    def __init__(self, identity_str, curve_name):
+        """Configure for specific identity and elliptic curve usage."""
+        self.identity_dict = string_to_identity(identity_str)
+        self.curve_name = curve_name
+
+    def items(self):
+        """Return a copy of identity_dict items."""
+        return self.identity_dict.items()
+
+    def __str__(self):
+        """Return identity serialized to string."""
+        return '<{}|{}>'.format(identity_to_string(self.identity_dict), self.curve_name)
+
+    def get_bip32_address(self, ecdh=False):
+        """Compute BIP32 derivation address according to SLIP-0013/0017."""
+        index = struct.pack('<L', self.identity_dict.get('index', 0))
+        addr = index + identity_to_string(self.identity_dict).encode('ascii')
+        log.debug('bip32 address string: %r', addr)
+        digest = hashlib.sha256(addr).digest()
+        s = io.BytesIO(bytearray(digest))
+
+        hardened = 0x80000000
+        addr_0 = 17 if bool(ecdh) else 13
+        address_n = [addr_0] + list(util.recv(s, '<LLLL'))
+        return [(hardened | value) for value in address_n]
+
+    def get_curve_name(self, ecdh=False):
+        """Return correct curve name for device operations."""
+        if ecdh:
+            return formats.get_ecdh_curve_name(self.curve_name)
+        else:
+            return self.curve_name
+
+
+class Device(object):
+    """Abstract cryptographic hardware device interface."""
+
+    def __init__(self):
+        """C-tor."""
+        self.conn = None
+
+    def connect(self):
+        """Connect to device, otherwise raise NotFoundError."""
+        raise NotImplementedError()
+
+    def __enter__(self):
+        """Allow usage as context manager."""
+        self.conn = self.connect()
+        return self
+
+    def __exit__(self, *args):
+        """Close and mark as disconnected."""
+        try:
+            self.conn.close()
+        except Exception as e:  # pylint: disable=broad-except
+            log.exception('close failed: %s', e)
+        self.conn = None
+
+    def pubkey(self, identity, ecdh=False):
+        """Get public key (as bytes)."""
+        raise NotImplementedError()
+
+    def sign(self, identity, blob):
+        """Sign given blob and return the signature (as bytes)."""
+        raise NotImplementedError()
+
+    def ecdh(self, identity, pubkey):
+        """Get shared session key using Elliptic Curve Diffie-Hellman."""
+        raise NotImplementedError()
+
+    def __str__(self):
+        """Human-readable representation."""
+        return '{}'.format(self.__class__.__name__)

libagent/device/keepkey.py

@@ -0,0 +1,37 @@
+"""KeepKey-related code (see https://www.keepkey.com/)."""
+
+from . import trezor
+from .. import formats
+
+
+def _verify_support(identity, ecdh):
+    """Make sure the device supports given configuration."""
+    protocol = identity.identity_dict['proto']
+    if protocol not in {'ssh'}:
+        raise NotImplementedError(
+            'Unsupported protocol: {}'.format(protocol))
+    if ecdh:
+        raise NotImplementedError('No support for ECDH')
+    if identity.curve_name not in {formats.CURVE_NIST256}:
+        raise NotImplementedError(
+            'Unsupported elliptic curve: {}'.format(identity.curve_name))
+
+
+class KeepKey(trezor.Trezor):
+    """Connection to KeepKey device."""
+
+    @property
+    def _defs(self):
+        from . import keepkey_defs
+        return keepkey_defs
+
+    required_version = '>=1.0.4'
+
+    def pubkey(self, identity, ecdh=False):
+        """Return public key."""
+        _verify_support(identity, ecdh)
+        return trezor.Trezor.pubkey(self, identity=identity, ecdh=ecdh)
+
+    def ecdh(self, identity, pubkey):
+        """No support for ECDH in KeepKey firmware."""
+        _verify_support(identity, ecdh=True)

libagent/device/keepkey_defs.py

@@ -0,0 +1,9 @@
+"""KeepKey-related definitions."""
+
+# pylint: disable=unused-import,import-error
+
+from keepkeylib.client import CallException as Error
+from keepkeylib.client import KeepKeyClient as Client
+from keepkeylib.messages_pb2 import PassphraseAck
+from keepkeylib.transport_hid import HidTransport as Transport
+from keepkeylib.types_pb2 import IdentityType

libagent/device/ledger.py

@@ -0,0 +1,111 @@
+"""Ledger-related code (see https://www.ledgerwallet.com/)."""
+
+import binascii
+import logging
+import struct
+
+from ledgerblue import comm  # pylint: disable=import-error
+
+from . import interface
+
+log = logging.getLogger(__name__)
+
+
+def _expand_path(path):
+    """Convert BIP32 path into bytes."""
+    return b''.join((struct.pack('>I', e) for e in path))
+
+
+def _convert_public_key(ecdsa_curve_name, result):
+    """Convert Ledger reply into PublicKey object."""
+    if ecdsa_curve_name == 'nist256p1':
+        if (result[64] & 1) != 0:
+            result = bytearray([0x03]) + result[1:33]
+        else:
+            result = bytearray([0x02]) + result[1:33]
+    else:
+        result = result[1:]
+        keyX = bytearray(result[0:32])
+        keyY = bytearray(result[32:][::-1])
+        if (keyX[31] & 1) != 0:
+            keyY[31] |= 0x80
+        result = b'\x00' + bytes(keyY)
+    return bytes(result)
+
+
+class LedgerNanoS(interface.Device):
+    """Connection to Ledger Nano S device."""
+
+    def connect(self):
+        """Enumerate and connect to the first USB HID interface."""
+        try:
+            return comm.getDongle()
+        except comm.CommException as e:
+            raise interface.NotFoundError(
+                '{} not connected: "{}"'.format(self, e))
+
+    def pubkey(self, identity, ecdh=False):
+        """Get PublicKey object for specified BIP32 address and elliptic curve."""
+        curve_name = identity.get_curve_name(ecdh)
+        path = _expand_path(identity.get_bip32_address(ecdh))
+        if curve_name == 'nist256p1':
+            p2 = '01'
+        else:
+            p2 = '02'
+        apdu = '800200' + p2
+        apdu = binascii.unhexlify(apdu)
+        apdu += bytearray([len(path) + 1, len(path) // 4])
+        apdu += path
+        result = bytearray(self.conn.exchange(bytes(apdu)))[1:]
+        return _convert_public_key(curve_name, result)
+
+    def sign(self, identity, blob):
+        """Sign given blob and return the signature (as bytes)."""
+        path = _expand_path(identity.get_bip32_address(ecdh=False))
+        if identity.identity_dict['proto'] == 'ssh':
+            ins = '04'
+            p1 = '00'
+        else:
+            ins = '08'
+            p1 = '00'
+        if identity.curve_name == 'nist256p1':
+            p2 = '81' if identity.identity_dict['proto'] == 'ssh' else '01'
+        else:
+            p2 = '82' if identity.identity_dict['proto'] == 'ssh' else '02'
+        apdu = '80' + ins + p1 + p2
+        apdu = binascii.unhexlify(apdu)
+        apdu += bytearray([len(blob) + len(path) + 1])
+        apdu += bytearray([len(path) // 4]) + path
+        apdu += blob
+        result = bytearray(self.conn.exchange(bytes(apdu)))
+        if identity.curve_name == 'nist256p1':
+            offset = 3
+            length = result[offset]
+            r = result[offset+1:offset+1+length]
+            if r[0] == 0:
+                r = r[1:]
+            offset = offset + 1 + length + 1
+            length = result[offset]
+            s = result[offset+1:offset+1+length]
+            if s[0] == 0:
+                s = s[1:]
+            offset = offset + 1 + length
+            return bytes(r) + bytes(s)
+        else:
+            return bytes(result[:64])
+
+    def ecdh(self, identity, pubkey):
+        """Get shared session key using Elliptic Curve Diffie-Hellman."""
+        path = _expand_path(identity.get_bip32_address(ecdh=True))
+        if identity.curve_name == 'nist256p1':
+            p2 = '01'
+        else:
+            p2 = '02'
+        apdu = '800a00' + p2
+        apdu = binascii.unhexlify(apdu)
+        apdu += bytearray([len(pubkey) + len(path) + 1])
+        apdu += bytearray([len(path) // 4]) + path
+        apdu += pubkey
+        result = bytearray(self.conn.exchange(bytes(apdu)))
+        assert result[0] == 0x04
+        return bytes(result)

libagent/device/trezor.py

@@ -0,0 +1,117 @@
+"""TREZOR-related code (see http://bitcointrezor.com/)."""
+
+import binascii
+import logging
+import os
+
+import semver
+
+from . import interface
+
+log = logging.getLogger(__name__)
+
+
+class Trezor(interface.Device):
+    """Connection to TREZOR device."""
+
+    @property
+    def _defs(self):
+        from . import trezor_defs
+        # Allow using TREZOR bridge transport (instead of the HID default)
+        trezor_defs.Transport = {
+            'bridge': trezor_defs.BridgeTransport,
+        }.get(os.environ.get('TREZOR_TRANSPORT'), trezor_defs.HidTransport)
+        return trezor_defs
+
+    required_version = '>=1.4.0'
+    passphrase = os.environ.get('TREZOR_PASSPHRASE', '')
+
+    def connect(self):
+        """Enumerate and connect to the first USB HID interface."""
+        def passphrase_handler(_):
+            log.debug('using %s passphrase for %s',
+                      'non-empty' if self.passphrase else 'empty', self)
+            return self._defs.PassphraseAck(passphrase=self.passphrase)
+
+        for d in self._defs.Transport.enumerate():
+            log.debug('endpoint: %s', d)
+            transport = self._defs.Transport(d)
+            connection = self._defs.Client(transport)
+            connection.callback_PassphraseRequest = passphrase_handler
+            f = connection.features
+            log.debug('connected to %s %s', self, f.device_id)
+            log.debug('label    : %s', f.label)
+            log.debug('vendor   : %s', f.vendor)
+            current_version = '{}.{}.{}'.format(f.major_version,
+                                                f.minor_version,
+                                                f.patch_version)
+            log.debug('version  : %s', current_version)
+            log.debug('revision : %s', binascii.hexlify(f.revision))
+            if not semver.match(current_version, self.required_version):
+                fmt = ('Please upgrade your {} firmware to {} version'
+                       ' (current: {})')
+                raise ValueError(fmt.format(self, self.required_version,
+                                            current_version))
+            connection.ping(msg='', pin_protection=True)  # unlock PIN
+            return connection
+        raise interface.NotFoundError('{} not connected'.format(self))
+
+    def close(self):
+        """Close connection."""
+        self.conn.close()
+
+    def pubkey(self, identity, ecdh=False):
+        """Return public key."""
+        curve_name = identity.get_curve_name(ecdh=ecdh)
+        log.debug('"%s" getting public key (%s) from %s',
+                  identity, curve_name, self)
+        addr = identity.get_bip32_address(ecdh=ecdh)
+        result = self.conn.get_public_node(n=addr,
+                                           ecdsa_curve_name=curve_name)
+        log.debug('result: %s', result)
+        return result.node.public_key
+
+    def _identity_proto(self, identity):
+        result = self._defs.IdentityType()
+        for name, value in identity.items():
+            setattr(result, name, value)
+        return result
+
+    def sign(self, identity, blob):
+        """Sign given blob and return the signature (as bytes)."""
+        curve_name = identity.get_curve_name(ecdh=False)
+        log.debug('"%s" signing %r (%s) on %s',
+                  identity, blob, curve_name, self)
+        try:
+            result = self.conn.sign_identity(
+                identity=self._identity_proto(identity),
+                challenge_hidden=blob,
+                challenge_visual='',
+                ecdsa_curve_name=curve_name)
+            log.debug('result: %s', result)
+            assert len(result.signature) == 65
+            assert result.signature[:1] == b'\x00'
+            return result.signature[1:]
+        except self._defs.Error as e:
+            msg = '{} error: {}'.format(self, e)
+            log.debug(msg, exc_info=True)
+            raise interface.DeviceError(msg)
+
+    def ecdh(self, identity, pubkey):
+        """Get shared session key using Elliptic Curve Diffie-Hellman."""
+        curve_name = identity.get_curve_name(ecdh=True)
+        log.debug('"%s" shared session key (%s) for %r from %s',
+                  identity, curve_name, pubkey, self)
+        try:
+            result = self.conn.get_ecdh_session_key(
+                identity=self._identity_proto(identity),
+                peer_public_key=pubkey,
+                ecdsa_curve_name=curve_name)
+            log.debug('result: %s', result)
+            assert len(result.session_key) in {65, 33}  # NIST256 or Curve25519
+            assert result.session_key[:1] == b'\x04'
+            return result.session_key
+        except self._defs.Error as e:
+            msg = '{} error: {}'.format(self, e)
+            log.debug(msg, exc_info=True)
+            raise interface.DeviceError(msg)

libagent/device/trezor_defs.py

@@ -0,0 +1,10 @@
+"""TREZOR-related definitions."""
+
+# pylint: disable=unused-import,import-error
+
+from trezorlib.client import CallException as Error
+from trezorlib.client import TrezorClient as Client
+from trezorlib.messages_pb2 import PassphraseAck
+from trezorlib.transport_bridge import BridgeTransport
+from trezorlib.transport_hid import HidTransport
+from trezorlib.types_pb2 import IdentityType