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

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)