🗓 Sep 25, 2023 7:52:57 PM

✨ to/from_base62
🧪 tests added/updated
🐙 plugins updated

TODO

@@ -29,6 +29,7 @@ New ideas:
   ☐ 🐙 diff show results only
   ☐ ✨ brainfuck encoder/decoder
   ☐ ✨ spoon encoder/decoder
+  base62
 
 Bug:
 

chepy/__version__.py

@@ -1,2 +1,2 @@
-__version__ = "6.2.0"  # pragma: no cover
+__version__ = "6.3.0"  # pragma: no cover
 __author__ = "@securisec"  # pragma: no cover

chepy/modules/dataformat.py

@@ -1921,3 +1921,48 @@ def rotate_left(self, radix: int = 1, carry: bool = False) -> DataFormatT:
         else:
             self.state = r.rot(Rotate.rotate_left)
         return self
+
+    @ChepyDecorators.call_stack
+    def to_base62(
+        self,
+        alphabet: str = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz",
+    ) -> DataFormatT:
+        """Encode to base62
+
+        Args:
+            alphabet (str, optional): Alphabet. Defaults to "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz".
+
+        Returns:
+            Chepy: The Chepy object
+        """
+        base62 = []
+        num = int.from_bytes(self._convert_to_bytes(), byteorder="big")
+
+        while num > 0:
+            num, remainder = divmod(num, 62)
+            base62.insert(0, alphabet[remainder])
+
+        self.state = "".join(base62)
+        return self
+
+    @ChepyDecorators.call_stack
+    def from_base62(
+        self,
+        alphabet: str = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz",
+    ) -> DataFormatT:
+        """Decode from base62
+
+        Args:
+            alphabet (str, optional): Alphabet. Defaults to "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz".
+
+        Returns:
+            Chepy: The Chepy object.
+        """
+        base62_dict = {char: index for index, char in enumerate(alphabet)}
+        num = 0
+        for char in self._convert_to_str():
+            num = num * 62 + base62_dict[char]
+        decoded_data = num.to_bytes((num.bit_length() + 7) // 8, byteorder="big")
+
+        self.state = decoded_data
+        return self

chepy/modules/dataformat.pyi

@@ -103,3 +103,5 @@ class DataFormat(ChepyCore):
     def from_base(self: DataFormatT, radix: int=16) -> DataFormatT: ...
     def rotate_right(self: DataFormatT, radix: int=1, carry: bool=False) -> DataFormatT: ...
     def rotate_left(self: DataFormatT, radix: int=1, carry: bool=False) -> DataFormatT: ...
+    def to_base62(self: DataFormatT, alphabet: str="0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz") -> DataFormatT: ...
+    def from_base62(self: DataFormatT, alphabet: str="0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz") -> DataFormatT: ...

tests/test_ctf.py

@@ -41,3 +41,16 @@ def test_springforward_23_hours_behind():
     c = Chepy("vqkk{0vtg_b1um_e1tt_b3tt}")
     c.rotate_bruteforce().dict_get_items().filter_list("nicc")
     assert c.o == b"nicc{0nly_t1me_w1ll_t3ll}"
+
+
+def test_bsides_c5():
+    c = (
+        Chepy(
+            "BtC8EzBDHPOhKvzY6zyWRuy4lFMQNxDk9zLIG93n50uD83gxB9vg5jq7ZQJ50xpHMrUCwk4dRwtA0yGRSIDTFZ"
+        )
+        .from_base62()
+        .reverse()
+        .from_octal()
+        .o
+        == b"th3_cak3_is_a_li3"
+    )

tests/test_dataformat.py

@@ -622,3 +622,11 @@ def test_rotate_left():
         Chepy("d445d4a7e477d3d3").from_hex().rotate_left(radix=4, carry=True).o
         == b"D]J~G}=="
     )
+
+
+def test_base62():
+    assert (
+        Chepy(b"hello !!123!! world\xcc").to_base62().o
+        == b"EtWxGEdLPmwchEzFHWNyyyI3p1w"
+    )
+    assert Chepy("3bfP0XZgTym6SsUKeZS5Z6qoKa").from_base62().o == b"hello !!123!! world"