Reorganize AES module

pyrogram/client/client.py

@@ -1213,11 +1213,13 @@ class Client(Methods, BaseClient):
                             chunk = r2.bytes
 
                             # https://core.telegram.org/cdn#decrypting-files
-                            decrypted_chunk = AES.ctr_decrypt(
+                            decrypted_chunk = AES.ctr256_decrypt(
                                 chunk,
                                 r.encryption_key,
-                                r.encryption_iv,
+                                bytearray(
-                                offset
+                                    r.encryption_iv[:-4]
+                                    + (offset // 16).to_bytes(4, "big")
+                                )
                             )
 
                             hashes = session.send(

pyrogram/crypto/aes.py

@@ -22,47 +22,60 @@ log = logging.getLogger(__name__)
 
 try:
     import tgcrypto
+
+    log.info("Using TgCrypto")
+
+
+    class AES:
+        @classmethod
+        def ige256_encrypt(cls, data: bytes, key: bytes, iv: bytes) -> bytes:
+            return tgcrypto.ige256_encrypt(data, key, iv)
+
+        @classmethod
+        def ige256_decrypt(cls, data: bytes, key: bytes, iv: bytes) -> bytes:
+            return tgcrypto.ige256_decrypt(data, key, iv)
+
+        @staticmethod
+        def ctr256_encrypt(data: bytes, key: bytes, iv: bytearray, state: bytearray = None) -> bytes:
+            return tgcrypto.ctr256_encrypt(data, key, iv, state or bytearray(1))
+
+        @staticmethod
+        def ctr256_decrypt(data: bytes, key: bytes, iv: bytearray, state: bytearray = None) -> bytes:
+            return tgcrypto.ctr256_decrypt(data, key, iv, state or bytearray(1))
+
+        @staticmethod
+        def xor(a: bytes, b: bytes) -> bytes:
+            return int.to_bytes(
+                int.from_bytes(a, "big") ^ int.from_bytes(b, "big"),
+                len(a),
+                "big",
+            )
 except ImportError:
+    import pyaes
+
     log.warning(
         "TgCrypto is missing! "
         "Pyrogram will work the same, but at a much slower speed. "
         "More info: https://docs.pyrogram.ml/resources/TgCrypto"
     )
-    is_fast = False
-    import pyaes
-else:
-    log.info("Using TgCrypto")
-    is_fast = True
 
 
-# TODO: Ugly IFs
     class AES:
         @classmethod
         def ige256_encrypt(cls, data: bytes, key: bytes, iv: bytes) -> bytes:
-        if is_fast:
-            return tgcrypto.ige256_encrypt(data, key, iv)
-        else:
             return cls.ige(data, key, iv, True)
 
         @classmethod
         def ige256_decrypt(cls, data: bytes, key: bytes, iv: bytes) -> bytes:
-        if is_fast:
-            return tgcrypto.ige256_decrypt(data, key, iv)
-        else:
             return cls.ige(data, key, iv, False)
 
-    @staticmethod
+        @classmethod
-    def ctr256_encrypt(data: bytes, key: bytes, iv: bytes, state: bytes) -> bytes:
+        def ctr256_encrypt(cls, data: bytes, key: bytes, iv: bytearray, state: bytearray = None) -> bytes:
-        if is_fast:
+            return cls.ctr(data, key, iv, state or bytearray(1))
-            return tgcrypto.ctr256_decrypt(data, key, iv, state)
-        else:
-            ctr = pyaes.AESModeOfOperationCTR(key)
-            ctr._counter._counter = list(iv)
-            return ctr.decrypt(data)
 
-    @staticmethod
+        @classmethod
-    def ctr256_decrypt(data: bytes, key: bytes, iv: bytes, state: bytes) -> bytes:
+        def ctr256_decrypt(cls, data: bytes, key: bytes, iv: bytearray, state: bytearray = None) -> bytes:
-        return AES.ctr256_encrypt(data, key, iv, state)
+            return cls.ctr(data, key, iv, state or bytearray(1))
 
         @staticmethod
         def xor(a: bytes, b: bytes) -> bytes:
@@ -91,3 +104,31 @@ class AES:
                     iv_1 = chunk
 
             return b"".join(data)
+
+        @classmethod
+        def ctr(cls, data: bytes, key: bytes, iv: bytearray, state: bytearray) -> bytes:
+            cipher = pyaes.AES(key)
+
+            out = bytearray(data)
+            chunk = cipher.encrypt(iv)
+
+            for i in range(0, len(data), 16):
+                for j in range(0, min(len(data) - i, 16)):
+                    out[i + j] ^= chunk[state[0]]
+
+                    state[0] += 1
+
+                    if state[0] >= 16:
+                        state[0] = 0
+
+                    if state[0] == 0:
+                        for k in range(15, -1, -1):
+                            try:
+                                iv[k] += 1
+                                break
+                            except ValueError:
+                                iv[k] = 0
+
+                        chunk = cipher.encrypt(iv)
+
+            return out