Revert "Remove old code and use a better error message"

This reverts commit 7f13eef

pyrogram/crypto/aes.py

@@ -16,33 +16,52 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with Pyrogram.  If not, see <http://www.gnu.org/licenses/>.
 
+import logging
+
+log = logging.getLogger(__name__)
+
 try:
     import tgcrypto
-except ImportError as e:
+except ImportError:
-    e.msg = (
+    log.warning(
-        "TgCrypto is missing and Pyrogram can't run without. "
+        "TgCrypto is missing! "
-        "Please install it using \"pip3 install tgcrypto\". "
+        "Pyrogram will work the same, but at a much slower speed. "
         "More info: https://docs.pyrogram.ml/resources/TgCrypto"
     )
-
+    is_fast = False
-    raise e
+    import pyaes
+else:
+    log.info("Using TgCrypto")
+    is_fast = True
 
 
+# TODO: Ugly IFs
 class AES:
     @classmethod
     def ige_encrypt(cls, data: bytes, key: bytes, iv: bytes) -> bytes:
-        return tgcrypto.ige_encrypt(data, key, iv)
+        if is_fast:
+            return tgcrypto.ige_encrypt(data, key, iv)
+        else:
+            return cls.ige(data, key, iv, True)
 
     @classmethod
     def ige_decrypt(cls, data: bytes, key: bytes, iv: bytes) -> bytes:
-        return tgcrypto.ige_decrypt(data, key, iv)
+        if is_fast:
+            return tgcrypto.ige_decrypt(data, key, iv)
+        else:
+            return cls.ige(data, key, iv, False)
 
     @staticmethod
     def ctr_decrypt(data: bytes, key: bytes, iv: bytes, offset: int) -> bytes:
         replace = int.to_bytes(offset // 16, 4, "big")
         iv = iv[:-4] + replace
 
-        return tgcrypto.ctr_decrypt(data, key, iv)
+        if is_fast:
+            return tgcrypto.ctr_decrypt(data, key, iv)
+        else:
+            ctr = pyaes.AESModeOfOperationCTR(key)
+            ctr._counter._counter = list(iv)
+            return ctr.decrypt(data)
 
     @staticmethod
     def xor(a: bytes, b: bytes) -> bytes:
@@ -51,3 +70,23 @@ class AES:
             len(a),
             "big",
         )
+
+    @classmethod
+    def ige(cls, data: bytes, key: bytes, iv: bytes, encrypt: bool) -> bytes:
+        cipher = pyaes.AES(key)
+
+        iv_1 = iv[:16]
+        iv_2 = iv[16:]
+
+        data = [data[i: i + 16] for i in range(0, len(data), 16)]
+
+        if encrypt:
+            for i, chunk in enumerate(data):
+                iv_1 = data[i] = cls.xor(cipher.encrypt(cls.xor(chunk, iv_1)), iv_2)
+                iv_2 = chunk
+        else:
+            for i, chunk in enumerate(data):
+                iv_2 = data[i] = cls.xor(cipher.decrypt(cls.xor(chunk, iv_2)), iv_1)
+                iv_1 = chunk
+
+        return b"".join(data)