feat(en/kisskh): Decrypt encrypted subtitles (aniyomiorg#2646)

src/en/kisskh/build.gradle

@@ -5,7 +5,7 @@ ext {
     extName = 'KissKH'
     pkgNameSuffix = 'en.kisskh'
     extClass = '.KissKH'
-    extVersionCode = 2
+    extVersionCode = 3
     libVersion = '13'
 }
 

src/en/kisskh/src/eu/kanade/tachiyomi/animeextension/en/kisskh/KissKH.kt

@@ -8,7 +8,6 @@ import eu.kanade.tachiyomi.animesource.model.Track
 import eu.kanade.tachiyomi.animesource.model.Video
 import eu.kanade.tachiyomi.animesource.online.AnimeHttpSource
 import eu.kanade.tachiyomi.network.GET
-import kotlinx.serialization.decodeFromString
 import kotlinx.serialization.json.Json
 import kotlinx.serialization.json.JsonArray
 import kotlinx.serialization.json.JsonObject
@@ -21,7 +20,6 @@ import okhttp3.Headers
 import okhttp3.OkHttpClient
 import okhttp3.Request
 import okhttp3.Response
-import uy.kohesive.injekt.api.get
 
 class KissKH : AnimeHttpSource() {
 
@@ -111,6 +109,8 @@ class KissKH : AnimeHttpSource() {
         return videosFromElement(response, id)
     }
 
+    private val subDecryptor by lazy { SubDecryptor(client, headers, baseUrl) }
+
     private fun videosFromElement(response: Response, id: String): List<Video> {
         val jsonData = response.body.string()
         val jObject = json.decodeFromString<JsonObject>(jsonData)
@@ -122,10 +122,16 @@ class KissKH : AnimeHttpSource() {
             try {
                 val suburl = item.jsonObject["src"]!!.jsonPrimitive.content
                 val lang = item.jsonObject["label"]!!.jsonPrimitive.content
-                subList.add(Track(suburl, lang))
+
+                if (suburl.endsWith("txt")) {
+                    subList.add(subDecryptor.getSubtitles(suburl, lang))
+                } else {
+                    subList.add(Track(suburl, lang))
+                }
             } catch (_: Error) {}
         }
         val videoUrl = jObject["Video"]!!.jsonPrimitive.content
+
         videoList.add(Video(videoUrl, "FirstParty", videoUrl, subtitleTracks = subList, headers = Headers.headersOf("referer", "https://kisskh.me/", "origin", "https://kisskh.me")))
 
         return videoList.reversed()

src/en/kisskh/src/eu/kanade/tachiyomi/animeextension/en/kisskh/SubDecryptor.kt

@@ -0,0 +1,80 @@
+package eu.kanade.tachiyomi.animeextension.en.kisskh
+
+import android.net.Uri
+import android.util.Base64
+import eu.kanade.tachiyomi.animesource.model.Track
+import eu.kanade.tachiyomi.network.GET
+import okhttp3.Headers
+import okhttp3.OkHttpClient
+import java.io.File
+import javax.crypto.Cipher
+import javax.crypto.spec.IvParameterSpec
+import javax.crypto.spec.SecretKeySpec
+
+class SubDecryptor(private val client: OkHttpClient, private val headers: Headers, private val baseurl: String) {
+    fun getSubtitles(subUrl: String, subLang: String): Track {
+        val subHeaders = headers.newBuilder().apply {
+            add("Accept", "application/json, text/plain, */*")
+            add("Origin", baseurl)
+            add("Referer", "$baseurl/")
+        }.build()
+
+        val subtitleData = client.newCall(
+            GET(subUrl, subHeaders),
+        ).execute().use { it.body.string() }
+
+        val chunks = subtitleData.split(CHUNK_REGEX)
+            .filter(String::isNotBlank)
+            .map(String::trim)
+
+        val decrypted = chunks.mapIndexed { index, chunk ->
+            val parts = chunk.split("\n")
+            val text = parts.slice(1 until parts.size)
+            val d = text.map { decrypt(it) }.joinToString("\n")
+
+            arrayOf(index + 1, parts.first(), d).joinToString("\n")
+        }.joinToString("\n\n")
+
+        val file = File.createTempFile("subs", "srt")
+            .also(File::deleteOnExit)
+
+        file.writeText(decrypted)
+        val uri = Uri.fromFile(file)
+
+        return Track(uri.toString(), subLang)
+    }
+
+    companion object {
+        private val CHUNK_REGEX by lazy { Regex("^\\d+$", RegexOption.MULTILINE) }
+
+        private val KEY = intArrayOf(942683446, 876098358, 875967282, 943142451)
+        private val IV = intArrayOf(909653298, 909193779, 925905208, 892483379)
+    }
+
+    private fun getKey(words: IntArray): SecretKeySpec {
+        val keyBytes = words.toByteArray()
+        return SecretKeySpec(keyBytes, "AES")
+    }
+
+    private fun decrypt(data: String): String {
+        val key = getKey(KEY)
+        val iv = IvParameterSpec(IV.toByteArray())
+
+        val cipher = Cipher.getInstance("AES/CBC/PKCS5Padding")
+        cipher.init(Cipher.DECRYPT_MODE, key, iv)
+
+        val encryptedBytes = Base64.decode(data, Base64.DEFAULT)
+        return String(cipher.doFinal(encryptedBytes), Charsets.UTF_8)
+    }
+
+    private fun IntArray.toByteArray(): ByteArray {
+        return ByteArray(size * 4).also { bytes ->
+            forEachIndexed { index, value ->
+                bytes[index * 4] = (value shr 24).toByte()
+                bytes[index * 4 + 1] = (value shr 16).toByte()
+                bytes[index * 4 + 2] = (value shr 8).toByte()
+                bytes[index * 4 + 3] = value.toByte()
+            }
+        }
+    }
+}