CODEWITHSUNDEEP
phpmysqlsecurityencryption
Andrew Cassidy
Andrew Cassidy

Reputation: 255

Encrypting the value of an ID presented on a barcode being used for a ticketing system

I'm building a fairly simple ticketing system in PHP where when a user purchases a ticket, they're emailed a PDF with a barcode attached, the barcode contains their order ID, which when scanned at the event, matches the ID of the order in the database and validates the ticket.

However, I don't want the order id to presented in plain text in the barcode, as somebody could simply create a barcode with one digit higher or lower than their own and then have a valid ticket. I've looked at MD5 and some other encryption algorithms, but they produce 64 bit alphanumeric strings, which aren't ideal, as there is a possibility of the need to type the number in rather than scanning it.

Ideally, an id would convert from something like 123 to 864374357, so it's still fairly simple for a human to type.

Any ideas on what the best method of creating a simple encryption like this would be?

Upvotes: 1

Views: 982

Answers (2)

Gergo Erdosi
Gergo Erdosi

Reputation: 42063

You could generate a short unique number which is then stored in a separate column in the database. You could write a function like:

function generate_random_number($length) {
    $random = '';

    for($i = 0; $i < $length; $i++) {
        $random .= rand(0, 9);
    }

    return $random;
}

And generate a unique number:

do {
    $unique = generate_random_number(10);
    $sql = "SELECT COUNT(*) FROM example_table WHERE unique_id = $unique";
    $res = $conn->query($sql);
} while($res->fetchColumn() > 0);

echo $unique;

Upvotes: 0

Chris Barcroft
Chris Barcroft

Reputation: 572

Take a look at this question here, I think it will give you what you need!

Basically, just take the MD5 (or any algorithm) hash and then run a little extra processing on it to convert it to a numeric format, or limit its length.

Upvotes: 1

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