From 1ced222120c00854865c5b16e89838235ed549ee Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sergey=20M=E2=80=A4?= <dstftw@gmail.com>
Date: Wed, 27 Nov 2019 02:26:42 +0700
Subject: [utils] Add generic caesar cipher and rot47

---
 youtube_dl/utils.py | 13 +++++++++++++
 1 file changed, 13 insertions(+)

(limited to 'youtube_dl')

diff --git a/youtube_dl/utils.py b/youtube_dl/utils.py
index 0d30075aa..b14603d8a 100644
--- a/youtube_dl/utils.py
+++ b/youtube_dl/utils.py
@@ -5383,6 +5383,19 @@ def decode_packed_codes(code):
         obfucasted_code)
 
 
+def caesar(s, alphabet, shift):
+    if shift == 0:
+        return s
+    l = len(alphabet)
+    return ''.join(
+        alphabet[(alphabet.index(c) + shift) % l] if c in alphabet else c
+        for c in s)
+
+
+def rot47(s):
+    return caesar(s, r'''!"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~''', 47)
+
+
 def parse_m3u8_attributes(attrib):
     info = {}
     for (key, val) in re.findall(r'(?P<key>[A-Z0-9-]+)=(?P<val>"[^"]+"|[^",]+)(?:,|$)', attrib):
-- 
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