<?php
// Benötigte Variablen
$iv = str_repeat("\x00", 16); // 16 Bytes Null-Initialisierungsvektor
$key = str_repeat("\x00", 16); // 16 Bytes Null-Schlüssel
$picc = "CACDEC6C5455EE52BB1DA40470963113"; // Eingabewert
//       112233445566778899
// AES-Entschlüsselung im CBC-Modus
$encrypted_data = hex2bin($picc); // Konvertiert den Hex-String in Binärdaten
$decrypted_data = openssl_decrypt($encrypted_data, 'aes-128-cbc', $key, OPENSSL_RAW_DATA, $iv);
 
 
// Extrahieren des Zählerwerts
$byte9 = ord($picc[9]); // 10. Byte (Index 9)
$byte8 = ord($picc[8]); // 9. Byte (Index 8)
$counter = ($byte9 << 8) | $byte8; // Zusammenfügen der Bytes (Big-Endian)
 
echo "$decrypted_data\n";
echo "$picc\n";
echo "Counter: $counter\n";
?>
 

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