A simple PHP class to check the validity of an identity card and to get some basic information like the age of the person.

IdentityCard.class.php

<?php
/**
 * PHP class to check the validity of an identity card and to get some basic information like the age of the person.
 *
 * @author  PHP-einfach.de <https://www.php-einfach.de/diverses/personalausweis-ueberpruefen/>
 * @author  Sebastian Krätzig <info@ts3-tools.info>
 */
class IdentityCard
{
    /**
     * Constructor
     */
    public function __construct()
    {
        // constructor
    }

    /**
     * Checks, if the identity card is a new type
     * 
     * @param  string    $identity_card_identifier Unique identity card identifier
     * @return boolean                             True, when the identity card is a new type, False when an old type
     * @throws Exception                           Returns an exception, when the type could not be identified
     */
    private function is_new_identity_card_type($identity_card_identifier = null)
    {
        if ($identity_card_identifier == null OR empty(trim($identity_card_identifier)))
        {
            throw new Exception("No unique identity card identifier was provided.");
        }

        // @todo Regex could be improved: https://de.wikipedia.org/wiki/Ausweisnummer
        if (!preg_match('/^[0-9A-Z]{10,11}\s[0-9]{7}\s[0-9A-Z]{7,8}\s[0-9]{1}$/', $identity_card_identifier))
        {
            throw new Exception("Unknown identity card type.");
        }

        $splits = explode(" ", strtoupper($identity_card_identifier));

        if (strlen($splits[0]) == 11 && strlen($splits[1]) == 7 && strlen($splits[2]) == 7 && strlen($splits[3]) == 1)
        {
            return false;
        }

        return true;
    }

    /**
     * Helper function to validate the identity card checksums
     *
     * @param   string  $id
     * @param   string  $checksum
     * @return  boolean True, when the checksum is valid
     */
    private function validate_checksum($id, $checknumber)
    {
        $p = 7;
        $sum = 0;

        for($i=0; $i < strlen($id); $i++)
        {
            $char = $id[$i];
            
            if ($char >= '0' && $char <= '9')
            {
                $int = intval($char);
            } else {
                $int = ord($char)-55;
            }

            $sum += $int*$p;
            
            if ($p==1)
            {
                $p=7;
            } elseif ($p==3) {
                $p=1;
            } elseif ($p==7) {
                $p=3;
            }
        }

        $last_number = substr(strval($sum), -1);
        
        if ($last_number != $checknumber)
        {
            return false;
        }

        return true;
    }
            
    /**
     * Checks, if the identity cards checksum is valid
     * 
     * @param  string    $identity_card_identifier Unique identity card identifier
     * @return boolean                             True, when the identity card checksum is valid, False when it's invalid
     * @throws Exception                           Returns an exception, when the type could not be identified
     */
    public function identity_card_checksum_is_valid($identity_card_identifier)
    {
        $splits = explode(" ", strtoupper($identity_card_identifier));

        $checksums = array();
        $checksums[] = array(substr($splits[0],0,9), substr($splits[0],9,1));
        $checksums[] = array(substr($splits[1],0,6), substr($splits[1],6,1));
        $checksums[] = array(substr($splits[2],0,6), substr($splits[2],6,1));
        $checksums[] = array(substr($splits[0],0,10).substr($splits[1],0,7).substr($splits[2],0,7), $splits[3]); 

        foreach($checksums as $checksum)
        {
            if (! $this->validate_checksum($checksum[0], $checksum[1]))
            {
                return false;
            }
        }

        return true;
    }

    /**
     * Checks, if the identity card is expired
     * 
     * @param  string  $identity_card_identifier Unique identity card identifier
     * @return boolean                           True, when the identity card is expired, False when it's still valid
     */
    public function identity_card_expired($identity_card_identifier)
    {
        $splits = explode(" ", $identity_card_identifier);
        
        $valid_until = mktime(0,0,0, substr($splits[2], 2, 2) , substr($splits[2], 4, 2) , "20".substr($splits[2], 0, 2));
      
        if (time() < $valid_until)
        {
            return false;
        }
      
        return true;
    }

    /**
     * Returns information about the person and identity card based on the unique identity card identifier
     * 
     * @param  string   $identity_card_identifier Unique identity card identifier
     * @return stdClass $data                     An object with information about the person (eg. birthday, identity card expiry date, country of origin, ...)
     * @throws Exception                          Returns an exception, when the type could not be identified
     */
    public function identity_card_info($identity_card_identifier)
    {
        $splits = explode(" ", $identity_card_identifier);

        $data = new stdClass();

        $data->birthday = new stdClass();
        $data->birthday->day = $splits[1][4].$splits[1][5];
        $data->birthday->month = $splits[1][2].$splits[1][3];
        $data->birthday->year = ($splits[1][0].$splits[1][1] > intval(date('y'))) ? '19'.$splits[1][0].$splits[1][1] : '20'.$splits[1][0].$splits[1][1];

        $data->identity_card = new stdClass();
        $data->identity_card->expiry = new stdClass();
        $data->identity_card->expiry->day = $splits[2][4].$splits[2][5];
        $data->identity_card->expiry->month = $splits[2][2].$splits[2][3];
        $data->identity_card->expiry->year = '20'.$splits[2][0].$splits[2][1];

        try {
            $is_new_identity_card_type = $this->is_new_identity_card_type($identity_card_identifier);
        } catch (Exception $exception) {
            throw new Exception($exception->getMessage());
        }

        if ($is_new_identity_card_type)
        {
            $data->country_of_origin = $splits[2][7];
        } else {
            $data->country_of_origin = $splits[0][10];
        }

        $data->authority_code = substr($splits[0], 0, 4);

        return $data;
    }
}

Example usage:

/**
 * New identity card since November 2010:
 * 
 * L1: IDD<<IdentityCardNumber<<<<<<<
 * L2: 5555<88888<<<<<<CheckNumber
 * 
 * Alter Personalausweis bis 2010:
 * 
 * L2: IdentityCardNumber<<5555<<88888<<<<<CheckNumber
 *
 * Required format for the PHP class: "IdentityCardNumber 5555 88888 CheckNumber" (divided by single spaces)
 */

// New identity card (Erika Mustermann)
$identity_card_identifier = "T220001293 6408125 2010315D 4";
// Old identity card (Erika Mustermann)
//$identity_card_identifier = "1220001297D 6408125 1710319 8";

$identity_card = new IdentityCard();

if(! $identity_card->identity_card_checksum_is_valid($identity_card_identifier))
{
    exit("Invalid identity card (checksum)!");
}

echo "Identity card information:<pre>";
try {
    $data = $identity_card->identity_card_info($identity_card_identifier);
} catch (Exception $exception) {
    exit("Error: ".$exception->getMessage());
}
print_r($data);

if($identity_card->identity_card_expired($identity_card_identifier))
{
    exit("Identity card expired!");
}