temporal state (currently tools for files decryption in JS do work

tgbotapi.core/src/jvmMain/kotlin/dev/inmo/tgbotapi/utils/passport/DecryptionContextRealization.kt

@@ -0,0 +1,40 @@
+package dev.inmo.tgbotapi.utils.passport
+
+import dev.inmo.micro_utils.crypto.decodeBase64
+import sun.security.rsa.RSAPublicKeyImpl
+import java.security.KeyFactory
+import java.security.interfaces.RSAPrivateKey
+import java.security.spec.PKCS8EncodedKeySpec
+import javax.crypto.Cipher
+
+private val regexToRemoveFromKey = Regex("(-----(BEGIN|END) ((?:.*? KEY)|CERTIFICATE)-----|[\\s])")
+
+private fun String.adaptKey() {
+    val replaced = replace(regexToRemoveFromKey, "")
+
+}
+
+/**
+ * @param key PKCS8
+ */
+actual class DecryptionContext actual constructor(key: String) {
+    private val privateKey: RSAPrivateKey = KeyFactory.getInstance("RSA").generatePrivate(
+        PKCS8EncodedKeySpec(key.replace(regexToRemoveFromKey, "").decodeBase64())
+    ) as RSAPrivateKey
+    private val chunkSize: Int = privateKey.modulus.bitLength() / 8
+
+    actual fun ByteArray.decrypt(): ByteArray {
+        return Cipher.getInstance("RSA/ECB/PKCS1Padding").run {
+            init(Cipher.DECRYPT_MODE, privateKey)
+            (0 until size step chunkSize).flatMap {
+                val firstIndex = it
+                val lastIndexExclusive = if (it + chunkSize > size) {
+                    size
+                } else {
+                    it + chunkSize
+                }
+                doFinal(copyOfRange(firstIndex, lastIndexExclusive)).toList()
+            }.toByteArray()
+        }
+    }
+}