Fix int to bytes conversion in python3 (#16)

* Fix int -> bytes conversion in python3

* Update version to 0.3.0

.gitignore

@@ -60,5 +60,8 @@ docs/_build/
 # PyBuilder
 target/
 
-#Ipython Notebook
+# Ipython Notebook
 .ipynb_checkpoints
+
+# Editors
+.idea/

README.rst

@@ -1,6 +1,10 @@
 django-encrypted-id
 ===================
 
+**Note**: Encrypted IDs generated by version 0.3.0 onwards will be different
+from those generated by version 0.2.0. But versions 0.3.x will decrypt the IDs
+generated by the version 0.2.0.
+
 **Note**: Version 0.2.0 is a breaking change from versions
 `0.1.x <https://github.com/amitu/django-encrypted-id/tree/v0.1>`_.
 If you've been using *ekey* in permalinks, then it is recommended for you to

encrypted_id/__init__.py

@@ -22,7 +22,7 @@
 from django.shortcuts import get_object_or_404 as go4
 
 
-__version__ = "0.2.0"
+__version__ = "0.3.0"
 __license__ = "BSD"
 __author__ = "Amit Upadhyay"
 __email__ = "[email protected]"
@@ -39,7 +39,7 @@ def __init__(self, msg="Failed to decrypt, invalid input."):
 def encode(the_id, sub_key):
     assert 0 <= the_id < 2 ** 64
 
-    crc = binascii.crc32(bytes(the_id)) & 0xffffffff
+    crc = binascii.crc32(str(the_id).encode('utf-8')) & 0xffffffff
 
     message = struct.pack(b"<IQxxxx", crc, the_id)
     assert len(message) == 16
@@ -49,13 +49,50 @@ def encode(the_id, sub_key):
     cypher = AES.new(key[:32], AES.MODE_CBC, iv)
 
     eid = base64.urlsafe_b64encode(cypher.encrypt(message)).replace(b"=", b"")
-    return eid.decode('utf-8')
+    return (b"$" + eid).decode("utf-8")
 
 
 def decode(e, sub_key):
     if isinstance(e, basestring):
         e = bytes(e.encode("ascii"))
 
+    if not e.startswith(b"$"):
+        return decode2(e, sub_key)
+    e = e[1:]
+
+    try:
+        padding = (3 - len(e) % 3) * b"="
+        e = base64.urlsafe_b64decode(e + padding)
+    except (TypeError, AttributeError, binascii.Error):
+        raise EncryptedIDDecodeError()
+
+    for key in getattr(settings, "SECRET_KEYS", [settings.SECRET_KEY]):
+        iv = hashlib.sha256((key + sub_key).encode('ascii')).digest()[:16]
+        cypher = AES.new(key[:32], AES.MODE_CBC, iv)
+        try:
+            msg = cypher.decrypt(e)
+        except ValueError:
+            raise EncryptedIDDecodeError()
+
+        try:
+            crc, the_id = struct.unpack(b"<IQxxxx", msg)
+        except struct.error:
+            raise EncryptedIDDecodeError()
+
+        try:
+            if crc != binascii.crc32(str(the_id).encode('utf-8')) & 0xffffffff:
+                continue
+        except (MemoryError, OverflowError):
+            raise EncryptedIDDecodeError()
+
+        return the_id
+    raise EncryptedIDDecodeError("Failed to decrypt, CRC never matched.")
+
+
+def decode2(e, sub_key):
+    if isinstance(e, basestring):
+        e = bytes(e.encode("ascii"))
+
     try:
         padding = (3 - len(e) % 3) * b"="
         e = base64.urlsafe_b64decode(e + padding)