gpg: add 'fake' device for GPG-integration testing

libagent/device/fake_device.py

@@ -0,0 +1,69 @@
+"""Fake device - ONLY FOR TESTS!!! (NEVER USE WITH REAL DATA)."""
+
+import hashlib
+import logging
+
+import ecdsa
+
+from . import interface
+from .. import formats
+
+log = logging.getLogger(__name__)
+
+
+def _verify_support(identity):
+    """Make sure the device supports given configuration."""
+    if identity.curve_name not in {formats.CURVE_NIST256}:
+        raise NotImplementedError(
+            'Unsupported elliptic curve: {}'.format(identity.curve_name))
+
+
+class FakeDevice(interface.Device):
+    """Connection to TREZOR device."""
+
+    def connect(self):
+        """Return "dummy" connection."""
+        log.critical('NEVER USE THIS CODE FOR REAL-LIFE USE-CASES!!!')
+        log.critical('ONLY FOR DEBUGGING AND TESTING!!!')
+        # The code below uses HARD-CODED secret key - and should be used ONLY
+        # for GnuPG integration tests (e.g. when no real device is available).
+        # pylint: disable=attribute-defined-outside-init
+        self.secexp = 1
+        self.sk = ecdsa.SigningKey.from_secret_exponent(
+            secexp=self.secexp, curve=ecdsa.curves.NIST256p, hashfunc=hashlib.sha256)
+        self.vk = self.sk.get_verifying_key()
+        return self
+
+    def close(self):
+        """Close connection."""
+        self.conn = None
+
+    def pubkey(self, identity, ecdh=False):
+        """Return public key."""
+        _verify_support(identity)
+        data = self.vk.to_string()
+        x, y = data[:32], data[32:]
+        prefix = bytearray([2 + (bytearray(y)[0] & 1)])
+        return bytes(prefix) + x
+
+    def sign(self, identity, blob):
+        """Sign given blob and return the signature (as bytes)."""
+        if identity.identity_dict['proto'] in {'ssh'}:
+            digest = hashlib.sha256(blob).digest()
+        else:
+            digest = blob
+        return self.sk.sign_digest_deterministic(digest=digest,
+                                                 hashfunc=hashlib.sha256)
+
+    def ecdh(self, identity, pubkey):
+        """Get shared session key using Elliptic Curve Diffie-Hellman."""
+        assert pubkey[:1] == b'\x04'
+        peer = ecdsa.VerifyingKey.from_string(
+            pubkey[1:],
+            curve=ecdsa.curves.NIST256p,
+            hashfunc=hashlib.sha256)
+        shared = ecdsa.VerifyingKey.from_public_point(
+            point=(peer.pubkey.point * self.secexp),
+            curve=ecdsa.curves.NIST256p,
+            hashfunc=hashlib.sha256)
+        return shared.to_string()