doio · September 8, 2017 09:13 · Jan 4, 2012
diff --git a/decrypt.rb b/decrypt.rb
@@ -0,0 +1,40 @@
+def read_m3u8(m3u8)
+    File.open(m3u8, 'r') do |file|
+        keyfile = nil
+        iv = 0
+        file.each_line do |line|
+            line.chomp!
+            if line =~ /^#EXT-X-KEY:METHOD=AES-128,URI="(.*?)"(,IV=0x(.*))?/
+                keyfile = $1
+                if $2
+                    iv = $3
+                    iv_gen = :random
+                else
+                    iv_gen = :sequence
+                end
+            elsif not line =~ /^#/
+                in_file = File.join(File.dirname(m3u8), line)
+                ext = File.extname(in_file)
+                out_file = File.join(File.dirname(in_file), File.basename(in_file, ext) + '.clear' + ext)
+                decrypt(in_file, keyfile, iv, out_file)
+                if iv_gen == :sequence
+                    iv += 1
+                end
+            end
+        end
+    end
+end
+
+def decrypt(in_file, keyfile, iv, out_file)
+    key = load_key(keyfile)
+    iv_hex = sprintf('%032x', iv)
+    %x{openssl aes-128-cbc -d -K #{key} -iv #{iv_hex} -nosalt -in #{in_file} -out #{out_file}}
+end
+
+def load_key(keyfile)
+    File.open(keyfile, 'rb') do |file|
+        file.read.unpack('H*')[0]
+    end
+end
+
+read_m3u8(ARGV[0])