[tests] add tests for preamble encoding

2 files changed, 33 insertions, 2 deletions

diff --git a/client/src/leap/soledad/client/_crypto.py b/client/src/leap/soledad/client/_crypto.py
index 4bbdd044..9f403cc9 100644
--- a/client/src/leap/soledad/client/_crypto.py
+++ b/client/src/leap/soledad/client/_crypto.py
@@ -192,7 +192,7 @@ class BlobEncryptor(object):
 
         sym_key = _get_sym_key_for_doc(doc_info.doc_id, secret)
         self._aes = AESWriter(sym_key)
-        self._aes.authenticate(self._make_preamble())
+        self._aes.authenticate(self._encode_preamble())
 
     @property
     def iv(self):
@@ -214,7 +214,7 @@ class BlobEncryptor(object):
         d.addCallback(lambda _: self._end_crypto_stream())
         return d
 
-    def _make_preamble(self):
+    def _encode_preamble(self):
         current_time = int(time.time())
 
         return PACMAN.pack(
diff --git a/testing/tests/client/test_crypto.py b/testing/tests/client/test_crypto.py
index 5411a4e8..852448e0 100644
--- a/testing/tests/client/test_crypto.py
+++ b/testing/tests/client/test_crypto.py
@@ -235,6 +235,37 @@ class SoledadCryptoAESTestCase(BaseSoledadTest):
             _crypto.decrypt_sym(cyphertext, wrongkey, iv)
 
 
+class PreambleTestCase(unittest.TestCase):
+    class doc_info:
+        doc_id = 'D-deadbeef'
+        rev = '397932e0c77f45fcb7c3732930e7e9b2:1'
+
+    def setUp(self):
+        inf = BytesIO(snowden1)
+        self.blob = _crypto.BlobEncryptor(
+            self.doc_info, inf,
+            secret='A' * 96)
+
+    def test_preamble_starts_with_magic_signature(self):
+        preamble = self.blob._encode_preamble()
+        assert preamble.startswith(_crypto.BLOB_SIGNATURE_MAGIC)
+
+    def test_preamble_has_cipher_metadata(self):
+        preamble = self.blob._encode_preamble()
+        unpacked = _crypto.PACMAN.unpack(preamble)
+        encryption_scheme, encryption_method = unpacked[1:3]
+        assert encryption_scheme in _crypto.ENC_SCHEME
+        assert encryption_method in _crypto.ENC_METHOD
+        assert unpacked[4] == self.blob.iv
+
+    def test_preamble_has_document_sync_metadata(self):
+        preamble = self.blob._encode_preamble()
+        unpacked = _crypto.PACMAN.unpack(preamble)
+        doc_id, doc_rev = unpacked[5:]
+        assert doc_id == self.doc_info.doc_id
+        assert doc_rev == self.doc_info.rev
+
+
 def _aes_encrypt(key, iv, data):
     backend = default_backend()
     cipher = Cipher(algorithms.AES(key), modes.GCM(iv), backend=backend)