fix: stegano error with odd-length

Author: deoktr

pof/utils/stegano/ipv6encoding.py

@@ -38,9 +38,8 @@ def encode(cls, string):
 
         for sc in string_chunks:
             string_chunk = sc
-            if len(string_chunk) < cls.IPV6_LEN:
-                padding = cls.IPV6_LEN - len(string_chunk)
-                # TODO (deoktr): choose this randomly (anything BUT the padding_byte)
+            padding = cls.IPV6_LEN - len(string_chunk)
+            if padding > 0:
                 string_chunk += b"1"
                 string_chunk += cls.padding_byte * (padding - 1)
 
@@ -53,6 +52,11 @@ def encode(cls, string):
 
             ipv6_list.append(ipv6)
 
+        if len(hex_string) % cls.IPV6_LEN == 0 and len(hex_string) > 0:
+            pad_chunk = (b"1" + cls.padding_byte * (cls.IPV6_LEN - 1)).decode()
+            ipv6_chunks = [pad_chunk[i : i + 4] for i in range(0, len(pad_chunk), 4)]
+            ipv6_list.append(":".join(ipv6_chunks))
+
         return ipv6_list
 
     @classmethod
@@ -78,7 +82,7 @@ def decode_tokens(cls, encoded_tokens):
         """IPv6 decode tokens.
 
         ```
-        binascii.a2b_hex("".join(["...",]).replace(":", "").strip("0")[:-1])
+        binascii.a2b_hex("".join(["...",]).replace(":", "").rstrip("0")[:-1])
         ```.
         """
         return [
@@ -100,7 +104,7 @@ def decode_tokens(cls, encoded_tokens):
             (STRING, repr("")),
             (OP, ")"),
             (OP, "."),
-            (NAME, "strip"),
+            (NAME, "rstrip"),
             (OP, "("),
             (STRING, repr(cls.padding_byte.decode())),
             (OP, ")"),

pof/utils/stegano/macencoding.py

@@ -37,9 +37,8 @@ def encode(cls, string):
 
         for sc in string_chunks:
             string_chunk = sc
-            if len(string_chunk) < cls.MAC_LEN:
-                padding = cls.MAC_LEN - len(string_chunk)
-                # TODO (deoktr): choose this randomly (anything BUT the padding_byte)
+            padding = cls.MAC_LEN - len(string_chunk)
+            if padding > 0:
                 string_chunk += b"1"
                 string_chunk += cls.padding_byte * (padding - 1)
 
@@ -52,6 +51,11 @@ def encode(cls, string):
 
             mac_list.append(mac)
 
+        if len(hex_string) % cls.MAC_LEN == 0 and len(hex_string) > 0:
+            pad_chunk = (b"1" + cls.padding_byte * (cls.MAC_LEN - 1)).decode()
+            mac_chunks = [pad_chunk[i : i + 2] for i in range(0, len(pad_chunk), 2)]
+            mac_list.append("-".join(mac_chunks))
+
         return mac_list
 
     @classmethod
@@ -77,7 +81,7 @@ def decode_tokens(cls, encoded_tokens):
         """MAC encoding decode tokens.
 
         ```
-        binascii.a2b_hex("".join(["...",]).replace("-", "").strip("0")[:-1])
+        binascii.a2b_hex("".join(["...",]).replace("-", "").rstrip("0")[:-1])
         ```.
         """
         return [
@@ -99,7 +103,7 @@ def decode_tokens(cls, encoded_tokens):
             (STRING, repr("")),
             (OP, ")"),
             (OP, "."),
-            (NAME, "strip"),
+            (NAME, "rstrip"),
             (OP, "("),
             (STRING, repr(cls.padding_byte.decode())),
             (OP, ")"),

pof/utils/stegano/uuidencoding.py

@@ -40,9 +40,8 @@ def encode(cls, string):
 
         for string_chunk in string_chunks:
             sc = string_chunk
-            if len(sc) < cls.UUID_LEN:
-                padding = cls.UUID_LEN - len(sc)
-                # TODO (deoktr): choose this randomly (anything BUT the padding_byte)
+            padding = cls.UUID_LEN - len(sc)
+            if padding > 0:
                 sc += b"1"
                 sc += cls.padding_byte * (padding - 1)
 
@@ -58,6 +57,17 @@ def encode(cls, string):
 
             uuid_list.append(uuid)
 
+        if len(hex_string) % cls.UUID_LEN == 0 and len(hex_string) > 0:
+            pc = (b"1" + cls.padding_byte * (cls.UUID_LEN - 1)).decode()
+            uuid_chunks = [
+                pc[0:8],
+                pc[8:12],
+                pc[12:16],
+                pc[16:20],
+                pc[20:],
+            ]
+            uuid_list.append("-".join(uuid_chunks))
+
         return uuid_list
 
     @classmethod
@@ -83,7 +93,7 @@ def decode_tokens(cls, encoded_tokens):
         """UUID decode tokens.
 
         ```
-        binascii.a2b_hex("".join(["...",]).replace("-", "").strip("0")[:-1])
+        binascii.a2b_hex("".join(["...",]).replace("-", "").rstrip("0")[:-1])
         ```
         """
         return [
@@ -105,7 +115,7 @@ def decode_tokens(cls, encoded_tokens):
             (STRING, '""'),
             (OP, ")"),
             (OP, "."),
-            (NAME, "strip"),
+            (NAME, "rstrip"),
             (OP, "("),
             (STRING, repr(cls.padding_byte.decode())),
             (OP, ")"),

tests/obfuscator/conftest.py

@@ -97,22 +97,6 @@ class SkipEntry:
         "*",
         "Fails: replaces inner function names with globals() lookups (KeyError on nested scope)",
     ),
-    # TODO: fix all
-    SkipEntry(
-        "IPv6Obfuscator",
-        "*",
-        "Fails: binascii.Error on odd-length source",
-    ),
-    SkipEntry(
-        "UUIDObfuscator",
-        "*",
-        "Fails: binascii.Error on odd-length source",
-    ),
-    SkipEntry(
-        "MACObfuscator",
-        "*",
-        "Fails: binascii.Error on odd-length source",
-    ),
 ]