Use core decodeHex/rc4/toHex instead of local copies

Replace hand-rolled hex decoding, RC4 and hex encoding with the shared keiyoushi.utils helpers, following keiyoushi/extensions-source#15640. The output is identical for every valid input, so no version bumps. - decodeHex: lib/m3u8server, lib/vidguardextractor, animepahe, uniquestream, gotaku, tioanimeh - rc4: anikototheme, lib/vidsrcextractor, aniwaves - toHex: lib/googledriveepisodes, googledrive, missav, serienstream, hanime, hexawatch, kayoanime, kickassanime, funanimetv, tranimeizle, cycity, iyf, xfani commit a96c552e11b22ef6bedb34b097de4a101e9455cf from keiyoushi/extensions-source#15640
2026-10-20 10:51:36 +00:00 · 2026-10-15 13:36:10 +07:00
parent e4d4183727
commit 6bc0f4cbb0
23 changed files with 69 additions and 85 deletions
--- a/lib-multisrc/anikototheme/src/eu/kanade/tachiyomi/multisrc/anikototheme/AnikotoTheme.kt
+++ b/lib-multisrc/anikototheme/src/eu/kanade/tachiyomi/multisrc/anikototheme/AnikotoTheme.kt
@@ -26,6 +26,7 @@ import keiyoushi.utils.LazyMutable
 import keiyoushi.utils.delegate
 import keiyoushi.utils.getPreferencesLazy
 import keiyoushi.utils.parseAs
+import keiyoushi.utils.rc4
 import keiyoushi.utils.tryParse
 import keiyoushi.utils.useAsJsoup
 import okhttp3.CacheControl
@@ -41,8 +42,6 @@ import java.math.RoundingMode
 import java.text.SimpleDateFormat
 import java.util.Locale
 import java.util.concurrent.TimeUnit
-import javax.crypto.Cipher
-import javax.crypto.spec.SecretKeySpec
 import kotlin.time.Duration.Companion.hours

 abstract class AnikotoTheme(
@@ -1079,10 +1078,7 @@ private object AnikotoUtils {
    }

    private fun rc4Encrypt(key: String, input: String): String {
-        val rc4Key = SecretKeySpec(key.toByteArray(), "RC4")
-        val cipher = Cipher.getInstance("RC4")
-        cipher.init(Cipher.ENCRYPT_MODE, rc4Key, cipher.parameters)
-        val output = cipher.doFinal(input.toByteArray())
+        val output = rc4(key.toByteArray(), input.toByteArray())
        return Base64.encode(output, Base64.URL_SAFE or Base64.NO_WRAP).toString(Charsets.UTF_8)
    }

--- a/lib/googledriveepisodes/src/aniyomi/lib/googledriveepisodes/GoogleDriveEpisodes.kt
+++ b/lib/googledriveepisodes/src/aniyomi/lib/googledriveepisodes/GoogleDriveEpisodes.kt
@@ -6,6 +6,7 @@ import eu.kanade.tachiyomi.network.POST
 import eu.kanade.tachiyomi.util.asJsoup
 import keiyoushi.utils.formatBytes
 import keiyoushi.utils.parseAs
+import keiyoushi.utils.toHex
 import kotlinx.serialization.Serializable
 import okhttp3.Headers
 import okhttp3.HttpUrl.Companion.toHttpUrl
@@ -118,7 +119,7 @@ class GoogleDriveEpisodes(private val client: OkHttpClient, private val headers:
        val sapisidhash = MessageDigest
            .getInstance("SHA-1")
            .digest("$timeNow $SAPISID $origin".toByteArray())
-            .joinToString("") { "%02x".format(it) }
+            .toHex()
        return "SAPISIDHASH ${timeNow}_$sapisidhash"
    }

--- a/lib/m3u8server/src/aniyomi/lib/m3u8server/M3u8HttpServer.kt
+++ b/lib/m3u8server/src/aniyomi/lib/m3u8server/M3u8HttpServer.kt
@@ -1,6 +1,7 @@
 package aniyomi.lib.m3u8server

 import android.util.Log
+import keiyoushi.utils.decodeHex
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.runBlocking
 import kotlinx.coroutines.withContext
@@ -362,18 +363,21 @@ class M3u8HttpServer(
        if (normalizedIv.length != 32) {
            throw IOException("Invalid AES-128 IV length: ${normalizedIv.length}")
        }
+        val ivBytes = try {
+            normalizedIv.decodeHex()
+        } catch (e: IllegalArgumentException) {
+            throw IOException("Invalid AES-128 IV", e)
+        }
        return try {
            val cipher = Cipher.getInstance("AES/CBC/PKCS5Padding")
            cipher.init(
                Cipher.DECRYPT_MODE,
                SecretKeySpec(key, "AES"),
-                IvParameterSpec(normalizedIv.hexToByteArray()),
+                IvParameterSpec(ivBytes),
            )
            cipher.doFinal(data)
        } catch (e: GeneralSecurityException) {
            throw IOException("Failed to decrypt AES-128 segment", e)
-        } catch (e: NumberFormatException) {
-            throw IOException("Invalid AES-128 IV", e)
        }
    }

@@ -381,10 +385,6 @@ class M3u8HttpServer(

    private fun String.normalizeHlsIv(): String = removePrefix("0x").removePrefix("0X").padStart(32, '0')

-    private fun String.hexToByteArray(): ByteArray = ByteArray(length / 2) { index ->
-        substring(index * 2, index * 2 + 2).toInt(16).toByte()
-    }
-
    /**
     * Health check
     */
--- a/lib/vidguardextractor/src/aniyomi/lib/vidguardextractor/VidGuardExtractor.kt
+++ b/lib/vidguardextractor/src/aniyomi/lib/vidguardextractor/VidGuardExtractor.kt
@@ -5,6 +5,7 @@ import android.util.Log
 import aniyomi.lib.playlistutils.PlaylistUtils
 import eu.kanade.tachiyomi.animesource.model.Video
 import eu.kanade.tachiyomi.network.GET
+import keiyoushi.utils.decodeHex
 import keiyoushi.utils.parseAs
 import keiyoushi.utils.useAsJsoup
 import kotlinx.serialization.Serializable
@@ -37,8 +38,8 @@ class VidGuardExtractor(private val client: OkHttpClient) {

    private fun sigDecode(url: String): String {
        val sig = url.split("sig=")[1].split("&")[0]
-        val t = sig.chunked(2)
-            .joinToString("") { (Integer.parseInt(it, 16) xor 2).toChar().toString() }
+        val t = sig.decodeHex()
+            .joinToString("") { ((it.toInt() and 0xFF) xor 2).toChar().toString() }
            .let {
                val padding = when (it.length % 4) {
                    2 -> "=="
--- a/lib/vidsrcextractor/src/aniyomi/lib/vidsrcextractor/VidSrcExtractor.kt
+++ b/lib/vidsrcextractor/src/aniyomi/lib/vidsrcextractor/VidSrcExtractor.kt
@@ -7,6 +7,7 @@ import eu.kanade.tachiyomi.animesource.model.Track
 import eu.kanade.tachiyomi.animesource.model.Video
 import eu.kanade.tachiyomi.network.GET
 import keiyoushi.utils.parseAs
+import keiyoushi.utils.rc4
 import kotlinx.serialization.ExperimentalSerializationApi
 import kotlinx.serialization.Serializable
 import kotlinx.serialization.json.Json
@@ -15,8 +16,6 @@ import okhttp3.HttpUrl.Companion.toHttpUrl
 import okhttp3.OkHttpClient
 import uy.kohesive.injekt.injectLazy
 import java.net.URLDecoder
-import javax.crypto.Cipher
-import javax.crypto.spec.SecretKeySpec

@OptIn(ExperimentalSerializationApi::class)
 class VidsrcExtractor(private val client: OkHttpClient, private val headers: Headers) {
@@ -76,10 +75,8 @@ class VidsrcExtractor(private val client: OkHttpClient, private val headers: Hea
    }

    private fun encodeID(videoID: String, key: String): String {
-        val rc4Key = SecretKeySpec(key.toByteArray(), "RC4")
-        val cipher = Cipher.getInstance("RC4")
-        cipher.init(Cipher.DECRYPT_MODE, rc4Key, cipher.parameters)
-        return Base64.encode(cipher.doFinal(videoID.toByteArray()), Base64.DEFAULT)
+        val encrypted = rc4(key.toByteArray(), videoID.toByteArray())
+        return Base64.encode(encrypted, Base64.DEFAULT)
            .toString(Charsets.UTF_8)
            .replace("+", "-")
            .replace("/", "_")
@@ -98,11 +95,7 @@ class VidsrcExtractor(private val client: OkHttpClient, private val headers: Hea
    }

    private fun vrfDecrypt(input: String): String {
-        var vrf = Base64.decode(input.toByteArray(), Base64.URL_SAFE)
-        val rc4Key = SecretKeySpec(DECRYPTION_KEY.toByteArray(), "RC4")
-        val cipher = Cipher.getInstance("RC4")
-        cipher.init(Cipher.DECRYPT_MODE, rc4Key, cipher.parameters)
-        vrf = cipher.doFinal(vrf)
+        val vrf = rc4(DECRYPTION_KEY.toByteArray(), Base64.decode(input.toByteArray(), Base64.URL_SAFE))
        return URLDecoder.decode(vrf.toString(Charsets.UTF_8), "utf-8")
    }

--- a/src/all/googledrive/src/eu/kanade/tachiyomi/animeextension/all/googledrive/GoogleDrive.kt
+++ b/src/all/googledrive/src/eu/kanade/tachiyomi/animeextension/all/googledrive/GoogleDrive.kt
@@ -25,6 +25,7 @@ import keiyoushi.utils.commonEmptyRequestBody
 import keiyoushi.utils.formatBytes
 import keiyoushi.utils.getPreferencesLazy
 import keiyoushi.utils.parseAs
+import keiyoushi.utils.toHex
 import kotlinx.serialization.encodeToString
 import kotlinx.serialization.json.Json
 import okhttp3.HttpUrl.Companion.toHttpUrl
@@ -510,7 +511,7 @@ class GoogleDrive :
        val sapisidhash = MessageDigest
            .getInstance("SHA-1")
            .digest("$timeNow $SAPISID $origin".toByteArray())
-            .joinToString("") { "%02x".format(it) }
+            .toHex()
        return "SAPISIDHASH ${timeNow}_$sapisidhash"
    }

--- a/src/all/missav/src/eu/kanade/tachiyomi/animeextension/all/missav/MissAvApi.kt
+++ b/src/all/missav/src/eu/kanade/tachiyomi/animeextension/all/missav/MissAvApi.kt
@@ -1,6 +1,7 @@
 package eu.kanade.tachiyomi.animeextension.all.missav

 import android.util.Log
+import keiyoushi.utils.toHex
 import kotlinx.serialization.json.JsonObjectBuilder
 import kotlinx.serialization.json.add
 import kotlinx.serialization.json.put
@@ -94,7 +95,7 @@ object MissAvApi {
        mac.init(secretKeySpec)

        val hashBytes = mac.doFinal(data.toByteArray(StandardCharsets.UTF_8))
-        val hexString = hashBytes.joinToString("") { "%02x".format(it) }
+        val hexString = hashBytes.toHex()

        "$data&frontend_sign=$hexString"
    } catch (e: Exception) {
--- a/src/de/serienstream/src/eu/kanade/tachiyomi/animeextension/de/serienstream/Serienstream.kt
+++ b/src/de/serienstream/src/eu/kanade/tachiyomi/animeextension/de/serienstream/Serienstream.kt
@@ -21,6 +21,7 @@ import keiyoushi.utils.delegate
 import keiyoushi.utils.getPreferencesLazy
 import keiyoushi.utils.parallelCatchingFlatMapBlocking
 import keiyoushi.utils.parallelMapNotNullBlocking
+import keiyoushi.utils.toHex
 import keiyoushi.utils.useAsJsoup
 import kotlinx.serialization.json.Json
 import kotlinx.serialization.json.JsonArray
@@ -443,7 +444,7 @@ class Serienstream :
        }
        for (i in 0..maxnumber) {
            val hash = md.digest((salt + i.toString()).toByteArray())
-            val hex = hash.joinToString("") { "%02x".format(it.toInt() and 0xFF) }
+            val hex = hash.toHex()
            if (hex == challenge) return i
            md.reset()
        }
--- a/src/en/animepahe/src/eu/kanade/tachiyomi/animeextension/en/animepahe/AnimePaheHlsServer.kt
+++ b/src/en/animepahe/src/eu/kanade/tachiyomi/animeextension/en/animepahe/AnimePaheHlsServer.kt
@@ -1,6 +1,7 @@
 package eu.kanade.tachiyomi.animeextension.en.animepahe

 import eu.kanade.tachiyomi.animesource.model.Video
+import keiyoushi.utils.decodeHex
 import okhttp3.Headers
 import okhttp3.HttpUrl
 import okhttp3.HttpUrl.Companion.toHttpUrlOrNull
@@ -339,18 +340,22 @@ object AnimePaheHlsServer : NanoHTTPD(0) {
            throw IOException("Invalid AES-128 IV length: ${normalizedIv.length}")
        }

+        val ivBytes = try {
+            normalizedIv.decodeHex()
+        } catch (e: IllegalArgumentException) {
+            throw IOException("Invalid AES-128 IV", e)
+        }
+
        return try {
            val cipher = Cipher.getInstance("AES/CBC/NoPadding")
            cipher.init(
                Cipher.DECRYPT_MODE,
                SecretKeySpec(key, "AES"),
-                IvParameterSpec(normalizedIv.hexToByteArray()),
+                IvParameterSpec(ivBytes),
            )
            cipher.doFinal(data)
        } catch (e: GeneralSecurityException) {
            throw IOException("Failed to decrypt AES-128 segment", e)
-        } catch (e: NumberFormatException) {
-            throw IOException("Invalid AES-128 IV", e)
        }
    }

@@ -359,8 +364,4 @@ object AnimePaheHlsServer : NanoHTTPD(0) {
    private fun String.normalizeHlsIv(): String = removePrefix("0x")
        .removePrefix("0X")
        .padStart(32, '0')
-
-    private fun String.hexToByteArray(): ByteArray = ByteArray(length / 2) { index ->
-        substring(index * 2, index * 2 + 2).toInt(16).toByte()
-    }
 }
--- a/src/en/aniwaves/src/eu/kanade/tachiyomi/animeextension/en/aniwaves/VrfCodec.kt
+++ b/src/en/aniwaves/src/eu/kanade/tachiyomi/animeextension/en/aniwaves/VrfCodec.kt
@@ -1,36 +1,18 @@
 package eu.kanade.tachiyomi.animeextension.en.aniwaves

 import android.util.Base64
+import keiyoushi.utils.rc4
 import java.net.URLEncoder

 internal class VrfCodec {

    fun encrypt(input: String): String {
-        val rc4Result = rc4(KEY, input)
-        val base64 = Base64.encodeToString(rc4Result.toByteArray(Charsets.ISO_8859_1), Base64.NO_WRAP)
+        val rc4Result = rc4(KEY, input.toByteArray(Charsets.ISO_8859_1))
+        val base64 = Base64.encodeToString(rc4Result, Base64.NO_WRAP)
        return URLEncoder.encode(base64, "UTF-8")
    }

-    private fun rc4(key: String, data: String): String {
-        val s = IntArray(256) { it }
-        var j = 0
-        for (i in 0..255) {
-            j = (j + s[i] + key[i % key.length].code) % 256
-            s[i] = s[j].also { s[j] = s[i] }
-        }
-        var i = 0
-        j = 0
-        val result = StringBuilder(data.length)
-        for (k in data.indices) {
-            i = (i + 1) % 256
-            j = (j + s[i]) % 256
-            s[i] = s[j].also { s[j] = s[i] }
-            result.append((data[k].code xor s[(s[i] + s[j]) % 256]).toChar())
-        }
-        return result.toString()
-    }
-
    private companion object {
-        const val KEY = "simple-hash"
+        val KEY = "simple-hash".toByteArray()
    }
 }
--- a/src/en/gotaku/src/eu/kanade/tachiyomi/animeextension/en/gotaku/Crypto.kt
+++ b/src/en/gotaku/src/eu/kanade/tachiyomi/animeextension/en/gotaku/Crypto.kt
@@ -1,6 +1,7 @@
 package eu.kanade.tachiyomi.animeextension.en.gotaku

 import android.util.Base64
+import keiyoushi.utils.decodeHex
 import kotlinx.serialization.json.buildJsonObject
 import kotlinx.serialization.json.put
 import okhttp3.HttpUrl.Companion.toHttpUrl
@@ -34,9 +35,7 @@ object Crypto {
        167, 208, 189, 122, 150, 242, 60, 1, 70, 177, 253, 150, 158, 124, 253, 47,
    ).map { it.toByte() }.toByteArray()

-    private val MANIFEST_SEED = hexToBytes(
-        "458e5403c40a73332706df406193dd6b040a2ea97a6bb59b52b294a61006e6ef",
-    )
+    private val MANIFEST_SEED = "458e5403c40a73332706df406193dd6b040a2ea97a6bb59b52b294a61006e6ef".decodeHex()

    /** HKDF-SHA256(ikm=API_SEED, salt=∅, info="api-seal|v1", L=32) — derived once. */
    private val apiKeySpec by lazy {
@@ -266,6 +265,4 @@ object Crypto {
    } catch (_: Exception) {
        null
    }
-
-    fun hexToBytes(hex: String): ByteArray = ByteArray(hex.length / 2) { i -> hex.substring(i * 2, i * 2 + 2).toInt(16).toByte() }
 }
--- a/src/en/hanime/src/eu/kanade/tachiyomi/animeextension/en/hanime/NativeSignatureProvider.kt
+++ b/src/en/hanime/src/eu/kanade/tachiyomi/animeextension/en/hanime/NativeSignatureProvider.kt
@@ -1,5 +1,6 @@
 package eu.kanade.tachiyomi.animeextension.en.hanime

+import keiyoushi.utils.toHex
 import java.security.MessageDigest

 /**
@@ -68,7 +69,7 @@ open class NativeSignatureProvider : SignatureProvider {
        val input = "$timestamp,$SALT_1,$ORIGIN,$SALT_2,$timestamp"
        val digest = MessageDigest.getInstance("SHA-256")
        val hashBytes = digest.digest(input.toByteArray(Charsets.UTF_8))
-        val hex = hashBytes.joinToString("") { "%02x".format(it) }
+        val hex = hashBytes.toHex()
        return Signature(signature = hex, time = timestamp.toString())
    }

--- a/src/en/hexawatch/src/eu/kanade/tachiyomi/animeextension/en/hexawatch/HexaWatch.kt
+++ b/src/en/hexawatch/src/eu/kanade/tachiyomi/animeextension/en/hexawatch/HexaWatch.kt
@@ -24,6 +24,7 @@ import keiyoushi.utils.getPreferencesLazy
 import keiyoushi.utils.parallelFlatMap
 import keiyoushi.utils.parallelMapNotNull
 import keiyoushi.utils.parseAs
+import keiyoushi.utils.toHex
 import keiyoushi.utils.toJsonRequestBody
 import keiyoushi.utils.toJsonString
 import kotlinx.coroutines.CancellationException
@@ -516,7 +517,7 @@ class HexaWatch :
    private class HosterData(val requestUrl: String, val server: String, val key: String, val url: String?)

    private fun randomHex(bytes: Int) = ByteArray(bytes).also(SECURE_RANDOM::nextBytes)
-        .joinToString("") { "%02x".format(it) }
+        .toHex()

    // Stands in for the site's hashed screen/UA/canvas fingerprint; only needs to be stable.
    private val clientFingerprint by lazy { randomHex(4).toLong(16).toString(36) }
--- a/src/en/kayoanime/src/eu/kanade/tachiyomi/animeextension/en/kayoanime/Kayoanime.kt
+++ b/src/en/kayoanime/src/eu/kanade/tachiyomi/animeextension/en/kayoanime/Kayoanime.kt
@@ -18,6 +18,7 @@ import keiyoushi.utils.ParsedAnimeHttpLegacySource
 import keiyoushi.utils.formatBytes
 import keiyoushi.utils.getPreferencesLazy
 import keiyoushi.utils.parseAs
+import keiyoushi.utils.toHex
 import kotlinx.serialization.Serializable
 import kotlinx.serialization.json.Json
 import okhttp3.FormBody
@@ -455,7 +456,7 @@ class Kayoanime :
        val sapisidhash = MessageDigest
            .getInstance("SHA-1")
            .digest("$timeNow $SAPISID $origin".toByteArray())
-            .joinToString("") { "%02x".format(it) }
+            .toHex()
        return "SAPISIDHASH ${timeNow}_$sapisidhash"
    }

--- a/src/en/kickassanime/src/eu/kanade/tachiyomi/animeextension/en/kickassanime/extractors/KickAssAnimeExtractor.kt
+++ b/src/en/kickassanime/src/eu/kanade/tachiyomi/animeextension/en/kickassanime/extractors/KickAssAnimeExtractor.kt
@@ -9,6 +9,7 @@ import eu.kanade.tachiyomi.network.awaitSuccess
 import keiyoushi.lib.cryptoaes.CryptoAES
 import keiyoushi.utils.bodyString
 import keiyoushi.utils.decodeHex
+import keiyoushi.utils.toHex
 import kotlinx.serialization.json.Json
 import okhttp3.Headers
 import okhttp3.HttpUrl.Companion.toHttpUrl
@@ -254,7 +255,7 @@ class KickAssAnimeExtractor(
    private fun sha1sum(value: String): String = try {
        val md = MessageDigest.getInstance("SHA-1")
        val bytes = md.digest(value.toByteArray())
-        bytes.joinToString("") { "%02x".format(it) }
+        bytes.toHex()
    } catch (_: Exception) {
        throw Exception("Attempt to create the signature failed.")
    }
--- a/src/en/uniquestream/src/eu/kanade/tachiyomi/animeextension/en/uniquestream/UniqueStreamHlsServer.kt
+++ b/src/en/uniquestream/src/eu/kanade/tachiyomi/animeextension/en/uniquestream/UniqueStreamHlsServer.kt
@@ -1,6 +1,7 @@
 package eu.kanade.tachiyomi.animeextension.en.uniquestream

 import android.util.Base64
+import keiyoushi.utils.decodeHex
 import okhttp3.Dns
 import okhttp3.HttpUrl
 import okhttp3.HttpUrl.Companion.toHttpUrlOrNull
@@ -258,18 +259,22 @@ object UniqueStreamHlsServer : NanoHTTPD("127.0.0.1", 0) {
            throw IOException("Invalid AES-128 key length: ${key.size}")
        }

+        val ivBytes = try {
+            iv.decodeHex()
+        } catch (e: IllegalArgumentException) {
+            throw IOException("Invalid AES-128 IV", e)
+        }
+
        return try {
            val cipher = Cipher.getInstance("AES/CBC/PKCS5Padding")
            cipher.init(
                Cipher.DECRYPT_MODE,
                SecretKeySpec(key, "AES"),
-                IvParameterSpec(iv.hexToByteArray()),
+                IvParameterSpec(ivBytes),
            )
            cipher.doFinal(data)
        } catch (e: GeneralSecurityException) {
            throw IOException("Failed to decrypt AES-128 segment", e)
-        } catch (e: IllegalArgumentException) {
-            throw IOException("Invalid AES-128 IV", e)
        }
    }

@@ -352,8 +357,4 @@ object UniqueStreamHlsServer : NanoHTTPD("127.0.0.1", 0) {
    private fun String.normalizeHlsIv(): String = removePrefix("0x").removePrefix("0X").padStart(32, '0')

    private fun encode(value: String): String = URLEncoder.encode(value, Charsets.UTF_8.name())
-
-    private fun String.hexToByteArray(): ByteArray = ByteArray(length / 2) { index ->
-        substring(index * 2, index * 2 + 2).toInt(16).toByte()
-    }
 }
--- a/src/es/tioanimeh/src/eu/kanade/tachiyomi/animeextension/es/tioanimeh/extractors/VidGuardExtractor.kt
+++ b/src/es/tioanimeh/src/eu/kanade/tachiyomi/animeextension/es/tioanimeh/extractors/VidGuardExtractor.kt
@@ -11,6 +11,7 @@ import android.webkit.WebViewClient
 import eu.kanade.tachiyomi.animesource.model.Video
 import eu.kanade.tachiyomi.network.GET
 import eu.kanade.tachiyomi.util.asJsoup
+import keiyoushi.utils.decodeHex
 import okhttp3.Headers
 import okhttp3.HttpUrl.Companion.toHttpUrl
 import okhttp3.OkHttpClient
@@ -105,8 +106,8 @@ class VidGuardExtractor(private val client: OkHttpClient) {
    private fun fixUrl(url: String): String {
        val httpUrl = url.toHttpUrl()
        val originalSign = httpUrl.queryParameter("sig")!!
-        val newSign = originalSign.chunked(2).joinToString("") {
-            Char(it.toInt(16) xor 2).toString()
+        val newSign = originalSign.decodeHex().joinToString("") {
+            Char((it.toInt() and 0xFF) xor 2).toString()
        }
            .let { String(Base64.decode(it, Base64.DEFAULT)) }
            .substring(5)
--- a/src/pt/funanimetv/src/eu/kanade/tachiyomi/animeextension/pt/funanimetv/FunAnimeTV.kt
+++ b/src/pt/funanimetv/src/eu/kanade/tachiyomi/animeextension/pt/funanimetv/FunAnimeTV.kt
@@ -19,6 +19,7 @@ import keiyoushi.network.rateLimit
 import keiyoushi.utils.AnimeHttpLegacySource
 import keiyoushi.utils.getPreferencesLazy
 import keiyoushi.utils.parseAs
+import keiyoushi.utils.toHex
 import keiyoushi.utils.toJsonString
 import kotlinx.coroutines.runBlocking
 import kotlinx.serialization.json.JsonObject
@@ -334,7 +335,7 @@ class FunAnimeTV :
    fun md5(input: String): String {
        val md = MessageDigest.getInstance("MD5")
        val digest = md.digest(input.toByteArray(Charsets.UTF_8))
-        return digest.joinToString(separator = "") { "%02x".format(it) }
+        return digest.toHex()
    }

    private fun createRequestJson(
--- a/src/pt/funanimetv/src/eu/kanade/tachiyomi/animeextension/pt/funanimetv/dto/FunAnimeTVDto.kt
+++ b/src/pt/funanimetv/src/eu/kanade/tachiyomi/animeextension/pt/funanimetv/dto/FunAnimeTVDto.kt
@@ -1,6 +1,7 @@
 package eu.kanade.tachiyomi.animeextension.pt.funanimetv.dto

 import android.util.Base64
+import keiyoushi.utils.toHex
 import kotlinx.serialization.SerialName
 import kotlinx.serialization.Serializable
 import kotlinx.serialization.Transient
@@ -24,9 +25,7 @@ class FunAnimeTVRequest(
    val sign: String = run {
        MessageDigest.getInstance("MD5")
            .digest("$singsalt$salt".toByteArray(Charsets.UTF_8))
-            .joinToString("") {
-                "%02x".format(it)
-            }
+            .toHex()
    }

    fun toBase64(json: Json): String = Base64.encodeToString(json.encodeToString(this).toByteArray(), Base64.NO_PADDING)
--- a/src/tr/tranimeizle/src/eu/kanade/tachiyomi/animeextension/tr/tranimeizle/ShittyCaptchaInterceptor.kt
+++ b/src/tr/tranimeizle/src/eu/kanade/tachiyomi/animeextension/tr/tranimeizle/ShittyCaptchaInterceptor.kt
@@ -2,6 +2,7 @@ package eu.kanade.tachiyomi.animeextension.tr.tranimeizle

 import eu.kanade.tachiyomi.network.GET
 import eu.kanade.tachiyomi.network.POST
+import keiyoushi.utils.toHex
 import okhttp3.FormBody
 import okhttp3.Headers
 import okhttp3.Interceptor
@@ -65,5 +66,5 @@ class ShittyCaptchaInterceptor(private val baseUrl: String, private val headers:

    private fun md5Hash(byteArray: ByteArray) = MessageDigest.getInstance("MD5")
        .digest(byteArray)
-        .joinToString("") { "%02x".format(it) } // create hex
+        .toHex()
 }
--- a/src/zh/cycity/src/eu/kanade/tachiyomi/animeextension/zh/cycity/Cycity.kt
+++ b/src/zh/cycity/src/eu/kanade/tachiyomi/animeextension/zh/cycity/Cycity.kt
@@ -17,6 +17,7 @@ import keiyoushi.lib.cryptoaes.CryptoAES
 import keiyoushi.utils.AnimeHttpLegacySource
 import keiyoushi.utils.getPreferencesLazy
 import keiyoushi.utils.parseAs
+import keiyoushi.utils.toHex
 import okhttp3.HttpUrl.Companion.toHttpUrl
 import okhttp3.Request
 import okhttp3.Response
@@ -75,7 +76,7 @@ class Cycity :
        val prefix = CharArray(k2.length)
        k1.indices.forEach { prefix[k1[it] - '0'] = k2[it] }
        val txt = "${prefix.joinToString("")}YLwJVbXw77pk2eOrAnFdBo2c3mWkLtodMni2wk81GCnP94ZltW"
-        val a = md5.digest(txt.toByteArray()).joinToString("") { "%02x".format(it) }
+        val a = md5.digest(txt.toByteArray()).toHex()
        val ivBytes = a.take(16).toByteArray(Charsets.UTF_8)
        val keyBytes = a.substring(16).toByteArray(Charsets.UTF_8)
        return CryptoAES.decrypt(url, keyBytes, ivBytes)
--- a/src/zh/iyf/src/eu/kanade/tachiyomi/animeextension/zh/iyf/Iyf.kt
+++ b/src/zh/iyf/src/eu/kanade/tachiyomi/animeextension/zh/iyf/Iyf.kt
@@ -10,6 +10,7 @@ import eu.kanade.tachiyomi.network.POST
 import eu.kanade.tachiyomi.util.asJsoup
 import keiyoushi.utils.AnimeHttpLegacySource
 import keiyoushi.utils.parseAs
+import keiyoushi.utils.toHex
 import kotlinx.serialization.json.Json
 import kotlinx.serialization.json.JsonElement
 import kotlinx.serialization.json.jsonArray
@@ -237,7 +238,7 @@ class Iyf : AnimeHttpLegacySource() {
    private fun signature(query: String, pConfig: PConfig): String {
        val s = "${pConfig.publicKey}&${query.lowercase()}&${pConfig.privateKey}"
        return MessageDigest.getInstance("MD5").digest(s.toByteArray())
-            .joinToString(separator = "") { "%02x".format(it) }
+            .toHex()
    }

    override fun getFilterList(): AnimeFilterList = AnimeFilterList(
--- a/src/zh/xfani/src/eu/kanade/tachiyomi/animeextension/zh/xfani/Signature.kt
+++ b/src/zh/xfani/src/eu/kanade/tachiyomi/animeextension/zh/xfani/Signature.kt
@@ -1,5 +1,6 @@
 package eu.kanade.tachiyomi.animeextension.zh.xfani

+import keiyoushi.utils.toHex
 import java.security.MessageDigest

 private const val UID = "DCC147D11943AF75"
@@ -9,5 +10,5 @@ internal fun generateKey(time: Long): String = "DS${time}$UID".md5()
 internal fun String.md5(): String {
    val md = MessageDigest.getInstance("MD5")
    val digest = md.digest(this.toByteArray())
-    return digest.joinToString(separator = "") { eachByte -> "%02x".format(eachByte) }
+    return digest.toHex()
 }