Fix detection of YouTube's decryption function

Closes TeamNewPipe/NewPipe#3951

Author: TobiGr

extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/extractors/YoutubeStreamExtractor.java

@@ -620,14 +620,14 @@ public String getErrorMessage() {
     private static final String HTTPS = "https:";
     private static final String DECRYPTION_FUNC_NAME = "decrypt";
 
-    private final static String DECRYPTION_SIGNATURE_FUNCTION_REGEX =
-            "([\\w$]+)\\s*=\\s*function\\((\\w+)\\)\\{\\s*\\2=\\s*\\2\\.split\\(\"\"\\)\\s*;";
-    private final static String DECRYPTION_SIGNATURE_FUNCTION_REGEX_2 =
-            "\\b([\\w$]{2})\\s*=\\s*function\\((\\w+)\\)\\{\\s*\\2=\\s*\\2\\.split\\(\"\"\\)\\s*;";
-    private final static String DECRYPTION_AKAMAIZED_STRING_REGEX =
-            "yt\\.akamaized\\.net/\\)\\s*\\|\\|\\s*.*?\\s*c\\s*&&\\s*d\\.set\\([^,]+\\s*,\\s*(:encodeURIComponent\\s*\\()([a-zA-Z0-9$]+)\\(";
-    private final static String DECRYPTION_AKAMAIZED_SHORT_STRING_REGEX =
-            "\\bc\\s*&&\\s*d\\.set\\([^,]+\\s*,\\s*(:encodeURIComponent\\s*\\()([a-zA-Z0-9$]+)\\(";
+    private final static String[] REGEXES = {
+            "(?:\\b|[^a-zA-Z0-9$])([a-zA-Z0-9$]{2})\\s*=\\s*function\\(\\s*a\\s*\\)\\s*\\{\\s*a\\s*=\\s*a\\.split\\(\\s*\"\"\\s*\\)",
+            "([\\w$]+)\\s*=\\s*function\\((\\w+)\\)\\{\\s*\\2=\\s*\\2\\.split\\(\"\"\\)\\s*;",
+            "\\b([\\w$]{2})\\s*=\\s*function\\((\\w+)\\)\\{\\s*\\2=\\s*\\2\\.split\\(\"\"\\)\\s*;",
+            "yt\\.akamaized\\.net/\\)\\s*\\|\\|\\s*.*?\\s*c\\s*&&\\s*d\\.set\\([^,]+\\s*,\\s*(:encodeURIComponent\\s*\\()([a-zA-Z0-9$]+)\\(",
+            "\\bc\\s*&&\\s*d\\.set\\([^,]+\\s*,\\s*(:encodeURIComponent\\s*\\()([a-zA-Z0-9$]+)\\("
+    };
+            ;
 
     private volatile String decryptionCode = "";
 
@@ -804,20 +804,15 @@ private String decryptSignature(String encryptedSig, String decryptionCode) thro
         return result == null ? "" : result.toString();
     }
 
-    private String getDecryptionFuncName(String playerCode) throws DecryptException {
-        String[] decryptionFuncNameRegexes = {
-                DECRYPTION_SIGNATURE_FUNCTION_REGEX_2,
-                DECRYPTION_SIGNATURE_FUNCTION_REGEX,
-                DECRYPTION_AKAMAIZED_SHORT_STRING_REGEX,
-                DECRYPTION_AKAMAIZED_STRING_REGEX
-        };
+    private String getDecryptionFuncName(final String playerCode) throws DecryptException {
         Parser.RegexException exception = null;
-        for (String regex : decryptionFuncNameRegexes) {
+        for (final String regex : REGEXES) {
             try {
                 return Parser.matchGroup1(regex, playerCode);
             } catch (Parser.RegexException re) {
-                if (exception == null)
+                if (exception == null) {
                     exception = re;
+                }
             }
         }
         throw new DecryptException("Could not find decrypt function with any of the given patterns.", exception);