diff --git a/app/src/main/java/us/beckmeyer/vvmsmsreceiver/SmsReceiver.kt b/app/src/main/java/us/beckmeyer/vvmsmsreceiver/SmsReceiver.kt
index 496fb9f..35b9da0 100644
--- a/app/src/main/java/us/beckmeyer/vvmsmsreceiver/SmsReceiver.kt
+++ b/app/src/main/java/us/beckmeyer/vvmsmsreceiver/SmsReceiver.kt
@@ -3,20 +3,24 @@ package us.beckmeyer.vvmsmsreceiver
 import android.content.BroadcastReceiver
 import android.content.Context
 import android.content.Intent
+import android.net.Uri
 import android.os.Bundle
 import android.provider.Telephony
 import android.telephony.SmsMessage
 import android.util.Log
+import kotlin.io.encoding.Base64
+import kotlin.io.encoding.ExperimentalEncodingApi
 
 
 class SmsReceiver : BroadcastReceiver() {
 
     private val TAG = "SmsReceiver"
 
-    @OptIn(ExperimentalStdlibApi::class)
+    @OptIn(ExperimentalStdlibApi::class, ExperimentalEncodingApi::class)
     override fun onReceive(context: Context, intent: Intent) {
         if (intent.action == Telephony.Sms.Intents.SMS_RECEIVED_ACTION ||
-            intent.action == Telephony.Sms.Intents.DATA_SMS_RECEIVED_ACTION) {
+            intent.action == Telephony.Sms.Intents.DATA_SMS_RECEIVED_ACTION
+        ) {
             val bundle: Bundle? = intent.extras
             bundle?.let {
                 val pdus = bundle.get("pdus") as Array<ByteArray>
@@ -26,6 +30,13 @@ class SmsReceiver : BroadcastReceiver() {
                     smsMessage?.let {
                         if (intent.action == Telephony.Sms.Intents.DATA_SMS_RECEIVED_ACTION) {
                             Log.d(TAG, "Data SMS received on port 5499")
+                            val bodyUri = Uri.parse("advvm://" + smsMessage.messageBody)
+                            bodyUri.getQueryParameter("p")?.let { p ->
+                                val ciphertext = Base64.decode(p).toString(Charsets.US_ASCII)
+                                Log.d(TAG, "ciphertext = $ciphertext")
+                                val password = decode(ciphertext, "8107308422")
+                                Log.d(TAG, "password = $password")
+                            }
                         }
                         val messageBody = smsMessage.messageBody
                         Log.d(TAG, "Message body: $messageBody")
@@ -36,4 +47,29 @@ class SmsReceiver : BroadcastReceiver() {
             }
         }
     }
+
+    private fun stripPrefix(char: Char): Int {
+        return char.code and 0x0F
+    }
+
+    private fun getStripped(text: String): ByteArray {
+        val stripped = text.map { stripPrefix(it).toByte() }
+        return stripped.toByteArray()
+    }
+
+    fun decode(cipher: String, phoneNumber: String): String {
+        val cipherStripped = getStripped(cipher)
+        val phoneNumberStripped = getStripped(phoneNumber)
+        val secret = byteArrayOf(12, 5, 3, 11, 9, 4, 5, 3, 8, 14)
+
+        val text = cipherStripped.zip(phoneNumberStripped)
+            .zip(secret.asIterable()) { (c, p), s -> (c.toInt() xor p.toInt() xor s.toInt()).toByte() }
+            .toMutableList()
+
+        if (cipherStripped.size > 10) {
+            text.addAll(cipherStripped.slice(10 until cipherStripped.size).toMutableList())
+        }
+
+        return text.toByteArray().map { (it + 0x30).toChar() }.joinToString("")
+    }
 }
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