lnonion: use random starting bytes in Sphinx packet as in updated BOLT4

see https://github.com/lightningnetwork/lightning-rfc/pull/697

electrum/lnonion.py

@@ -134,7 +134,7 @@ class OnionPacket:
 
 
 def get_bolt04_onion_key(key_type: bytes, secret: bytes) -> bytes:
-    if key_type not in (b'rho', b'mu', b'um', b'ammag'):
+    if key_type not in (b'rho', b'mu', b'um', b'ammag', b'pad'):
         raise Exception('invalid key_type {}'.format(key_type))
     key = hmac_oneshot(key_type, msg=secret, digest=hashlib.sha256)
     return key
@@ -163,9 +163,13 @@ def new_onion_packet(payment_path_pubkeys: Sequence[bytes], session_key: bytes,
     hop_shared_secrets = get_shared_secrets_along_route(payment_path_pubkeys, session_key)
 
     filler = generate_filler(b'rho', num_hops, PER_HOP_FULL_SIZE, hop_shared_secrets)
-    mix_header = bytes(HOPS_DATA_SIZE)
     next_hmac = bytes(PER_HOP_HMAC_SIZE)
 
+    # Our starting packet needs to be filled out with random bytes, we
+    # generate some determinstically using the session private key.
+    pad_key = get_bolt04_onion_key(b'pad', session_key)
+    mix_header = generate_cipher_stream(pad_key, HOPS_DATA_SIZE)
+
     # compute routing info and MAC for each hop
     for i in range(num_hops-1, -1, -1):
         rho_key = get_bolt04_onion_key(b'rho', hop_shared_secrets[i])

electrum/tests/test_lnrouter.py

@@ -141,7 +141,7 @@ class Test_LNRouter(TestCaseForTestnet):
             )),
         ]
         packet = new_onion_packet(payment_path_pubkeys, session_key, hops_data, associated_data)
-        self.assertEqual(bfh('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'),
+        self.assertEqual(bfh('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'),
                          packet.to_bytes())
 
     @needs_test_with_all_chacha20_implementations
@@ -182,7 +182,7 @@ class Test_LNRouter(TestCaseForTestnet):
             )),
         ]
         packet = new_onion_packet(payment_path_pubkeys, session_key, hops_data, associated_data)
-        self.assertEqual(bfh('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'),
+        self.assertEqual(bfh('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'),
                          packet.to_bytes())
         for i, privkey in enumerate(payment_path_privkeys):
             processed_packet = process_onion_packet(packet, associated_data, privkey)