[aes] Add unpad_pkcs7

Author: pukkandan

yt_dlp/aes.py

@@ -2,8 +2,15 @@
 
 from math import ceil
 
-from .compat import compat_b64decode, compat_pycrypto_AES
-from .utils import bytes_to_intlist, intlist_to_bytes
+from .compat import (
+    compat_b64decode,
+    compat_ord,
+    compat_pycrypto_AES,
+)
+from .utils import (
+    bytes_to_intlist,
+    intlist_to_bytes,
+)
 
 
 if compat_pycrypto_AES:
@@ -25,6 +32,10 @@ def aes_gcm_decrypt_and_verify_bytes(data, key, tag, nonce):
         return intlist_to_bytes(aes_gcm_decrypt_and_verify(*map(bytes_to_intlist, (data, key, tag, nonce))))
 
 
+def unpad_pkcs7(data):
+    return data[:-compat_ord(data[-1])]
+
+
 BLOCK_SIZE_BYTES = 16
 
 
@@ -506,5 +517,6 @@ def ghash(subkey, data):
     'aes_encrypt',
     'aes_gcm_decrypt_and_verify',
     'aes_gcm_decrypt_and_verify_bytes',
-    'key_expansion'
+    'key_expansion',
+    'unpad_pkcs7',
 ]

yt_dlp/cookies.py

@@ -11,7 +11,11 @@
 from enum import Enum, auto
 from hashlib import pbkdf2_hmac
 
-from .aes import aes_cbc_decrypt_bytes, aes_gcm_decrypt_and_verify_bytes
+from .aes import (
+    aes_cbc_decrypt_bytes,
+    aes_gcm_decrypt_and_verify_bytes,
+    unpad_pkcs7,
+)
 from .compat import (
     compat_b64decode,
     compat_cookiejar_Cookie,
@@ -846,10 +850,9 @@ def pbkdf2_sha1(password, salt, iterations, key_length):
 
 
 def _decrypt_aes_cbc(ciphertext, key, logger, initialization_vector=b' ' * 16):
-    plaintext = aes_cbc_decrypt_bytes(ciphertext, key, initialization_vector)
-    padding_length = plaintext[-1]
+    plaintext = unpad_pkcs7(aes_cbc_decrypt_bytes(ciphertext, key, initialization_vector))
     try:
-        return plaintext[:-padding_length].decode('utf-8')
+        return plaintext.decode('utf-8')
     except UnicodeDecodeError:
         logger.warning('failed to decrypt cookie (AES-CBC) because UTF-8 decoding failed. Possibly the key is wrong?', only_once=True)
         return None

yt_dlp/downloader/fragment.py

@@ -14,7 +14,7 @@
 
 from .common import FileDownloader
 from .http import HttpFD
-from ..aes import aes_cbc_decrypt_bytes
+from ..aes import aes_cbc_decrypt_bytes, unpad_pkcs7
 from ..compat import (
     compat_os_name,
     compat_urllib_error,
@@ -366,8 +366,7 @@ def decrypt_fragment(fragment, frag_content):
             # not what it decrypts to.
             if self.params.get('test', False):
                 return frag_content
-            decrypted_data = aes_cbc_decrypt_bytes(frag_content, decrypt_info['KEY'], iv)
-            return decrypted_data[:-decrypted_data[-1]]
+            return unpad_pkcs7(aes_cbc_decrypt_bytes(frag_content, decrypt_info['KEY'], iv))
 
         return decrypt_fragment
 

yt_dlp/extractor/adn.py

@@ -8,11 +8,10 @@
 import random
 
 from .common import InfoExtractor
-from ..aes import aes_cbc_decrypt
+from ..aes import aes_cbc_decrypt_bytes, unpad_pkcs7
 from ..compat import (
     compat_HTTPError,
     compat_b64decode,
-    compat_ord,
 )
 from ..utils import (
     ass_subtitles_timecode,
@@ -84,14 +83,11 @@ def _get_subtitles(self, sub_url, video_id):
             return None
 
         # http://animedigitalnetwork.fr/components/com_vodvideo/videojs/adn-vjs.min.js
-        dec_subtitles = intlist_to_bytes(aes_cbc_decrypt(
-            bytes_to_intlist(compat_b64decode(enc_subtitles[24:])),
-            bytes_to_intlist(binascii.unhexlify(self._K + 'ab9f52f5baae7c72')),
-            bytes_to_intlist(compat_b64decode(enc_subtitles[:24]))
-        ))
-        subtitles_json = self._parse_json(
-            dec_subtitles[:-compat_ord(dec_subtitles[-1])].decode(),
-            None, fatal=False)
+        dec_subtitles = unpad_pkcs7(aes_cbc_decrypt_bytes(
+            compat_b64decode(enc_subtitles[24:]),
+            binascii.unhexlify(self._K + 'ab9f52f5baae7c72'),
+            compat_b64decode(enc_subtitles[:24])))
+        subtitles_json = self._parse_json(dec_subtitles.decode(), None, fatal=False)
         if not subtitles_json:
             return None
 

yt_dlp/extractor/drtv.py

@@ -7,13 +7,11 @@
 
 
 from .common import InfoExtractor
-from ..aes import aes_cbc_decrypt
+from ..aes import aes_cbc_decrypt_bytes, unpad_pkcs7
 from ..compat import compat_urllib_parse_unquote
 from ..utils import (
-    bytes_to_intlist,
     ExtractorError,
     int_or_none,
-    intlist_to_bytes,
     float_or_none,
     mimetype2ext,
     str_or_none,
@@ -191,13 +189,11 @@ def hex_to_bytes(hex):
         def decrypt_uri(e):
             n = int(e[2:10], 16)
             a = e[10 + n:]
-            data = bytes_to_intlist(hex_to_bytes(e[10:10 + n]))
-            key = bytes_to_intlist(hashlib.sha256(
-                ('%s:sRBzYNXBzkKgnjj8pGtkACch' % a).encode('utf-8')).digest())
-            iv = bytes_to_intlist(hex_to_bytes(a))
-            decrypted = aes_cbc_decrypt(data, key, iv)
-            return intlist_to_bytes(
-                decrypted[:-decrypted[-1]]).decode('utf-8').split('?')[0]
+            data = hex_to_bytes(e[10:10 + n])
+            key = hashlib.sha256(('%s:sRBzYNXBzkKgnjj8pGtkACch' % a).encode('utf-8')).digest()
+            iv = hex_to_bytes(a)
+            decrypted = unpad_pkcs7(aes_cbc_decrypt_bytes(data, key, iv))
+            return decrypted.decode('utf-8').split('?')[0]
 
         for asset in assets:
             kind = asset.get('Kind')

yt_dlp/extractor/newstube.py

@@ -5,11 +5,9 @@
 import hashlib
 
 from .common import InfoExtractor
-from ..aes import aes_cbc_decrypt
+from ..aes import aes_cbc_decrypt_bytes, unpad_pkcs7
 from ..utils import (
-    bytes_to_intlist,
     int_or_none,
-    intlist_to_bytes,
     parse_codecs,
     parse_duration,
 )
@@ -47,10 +45,8 @@ def _real_extract(self, url):
             }))
         key = hashlib.pbkdf2_hmac(
             'sha1', video_guid.replace('-', '').encode(), enc_data[:16], 1)[:16]
-        dec_data = aes_cbc_decrypt(
-            bytes_to_intlist(enc_data[32:]), bytes_to_intlist(key),
-            bytes_to_intlist(enc_data[16:32]))
-        sources = self._parse_json(intlist_to_bytes(dec_data[:-dec_data[-1]]), video_guid)
+        dec_data = unpad_pkcs7(aes_cbc_decrypt_bytes(enc_data[32:], key, enc_data[16:32]))
+        sources = self._parse_json(dec_data, video_guid)
 
         formats = []
         for source in sources:

yt_dlp/extractor/rtl2.py

@@ -4,16 +4,13 @@
 import re
 
 from .common import InfoExtractor
-from ..aes import aes_cbc_decrypt
+from ..aes import aes_cbc_decrypt_bytes, unpad_pkcs7
 from ..compat import (
     compat_b64decode,
-    compat_ord,
     compat_str,
 )
 from ..utils import (
-    bytes_to_intlist,
     ExtractorError,
-    intlist_to_bytes,
     int_or_none,
     strip_or_none,
 )
@@ -142,17 +139,12 @@ def _real_extract(self, url):
             self._BACKWERK_BASE_URL + 'stream/video/' + video_id, video_id)
 
         data, iv = compat_b64decode(stream_data['streamUrl']).decode().split(':')
-        stream_url = intlist_to_bytes(aes_cbc_decrypt(
-            bytes_to_intlist(compat_b64decode(data)),
-            bytes_to_intlist(self._AES_KEY),
-            bytes_to_intlist(compat_b64decode(iv))
-        ))
+        stream_url = unpad_pkcs7(aes_cbc_decrypt_bytes(
+            compat_b64decode(data), self._AES_KEY, compat_b64decode(iv)))
         if b'rtl2_you_video_not_found' in stream_url:
             raise ExtractorError('video not found', expected=True)
 
-        formats = self._extract_m3u8_formats(
-            stream_url[:-compat_ord(stream_url[-1])].decode(),
-            video_id, 'mp4', 'm3u8_native')
+        formats = self._extract_m3u8_formats(stream_url.decode(), video_id, 'mp4', 'm3u8_native')
         self._sort_formats(formats)
 
         video_data = self._download_json(

yt_dlp/extractor/shemaroome.py

@@ -2,10 +2,9 @@
 from __future__ import unicode_literals
 
 from .common import InfoExtractor
-from ..aes import aes_cbc_decrypt
+from ..aes import aes_cbc_decrypt, unpad_pkcs7
 from ..compat import (
     compat_b64decode,
-    compat_ord,
 )
 from ..utils import (
     bytes_to_intlist,
@@ -76,8 +75,7 @@ def _real_extract(self, url):
         url_data = bytes_to_intlist(compat_b64decode(data_json['new_play_url']))
         key = bytes_to_intlist(compat_b64decode(data_json['key']))
         iv = [0] * 16
-        m3u8_url = intlist_to_bytes(aes_cbc_decrypt(url_data, key, iv))
-        m3u8_url = m3u8_url[:-compat_ord((m3u8_url[-1]))].decode('ascii')
+        m3u8_url = unpad_pkcs7(intlist_to_bytes(aes_cbc_decrypt(url_data, key, iv))).decode('ascii')
         formats, m3u8_subs = self._extract_m3u8_formats_and_subtitles(m3u8_url, video_id, fatal=False, headers={'stream_key': data_json['stream_key']})
         self._sort_formats(formats)