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Jason Gerfen wrote:
> Daniel Brown wrote:
>> On Dec 19, 2007 2:41 AM, Keith Spiller <larentium@xxxxxxxxxxxx> wrote:
>>> Ok I've done some research and some thinking. What about storing orders in
>>> the database (product info and customer info) and then using GnuPG or PGP to
>>> send the credit card info to the merchant? This way the credit card
>>> information is not stored on the server or in the database but only in
>>> printed format by the merchant. Since my client processes all of the credit
>>> card orders by hand this seems like an ideal solution.
>> I had a client that did offline (manual) processing of credit card
>> orders as well. With liability issues and the problems that others
>> have already pointed out, storing the credit card information was not
>> an option, yet my client still needed some way of having the data
>> available offline.
>
>> Consider the following:
>
>> ISSUER LENGTH
>> Diner's Club/Carte Blanche 14
>> American Express 15
>> VISA 13 or 16
>> MasterCard 16
>> Discover 16
>
>> Security checks aside (like making sure they selected the type of
>> card and that it matched the algorithm - VISA beginning with 4 and
>> being strlen($_POST['cardnum']) == 13 or 16, MasterCard being 16,
>> beginning with 51xx to 55xx, et cetera), I then had a hybrid of
>> storage and delivery.
>
>> Mail the first <? rand(4,6); ?> digits to the sales email
>> address(es) on file. Three addresses on two domains were used for
>> redundancy in this case. Store the remaining digits in the database.
>> You could write your own encryption algorithm or use one that is
>> publicly-available and reversible (Blowfish is what I was using, at
>> 128, key length of 56 lower ASCII characters, padded with 7 on the key
>> and four on the output - MD5, SHA1, et al are NOT options here).
>
>> The sales department then received the first digits of the credit
>> card number via email, which stated it was an order key. Again, in my
>
> Using the order number as the key is bad practice. Here is a random key
> generator that you could use for your public/private keys and still use
> the blowfish cipher as your method of encrypting:
>
> <?PHP
> function ReadFolder( $folder )
> {
> if( ( empty( $folder ) ) || ( !is_dir( $folder ) ) ) {
> $rand_image = GenerateError( "Couldn't open directory" );
> } else {
> $rand_image = array();
> if( $handle = opendir( $folder ) ) {
> while( false !== ( $file = readdir( $handle ) ) ) {
> if( $file != "." && $file != ".." && $file != "index.html" &&
> !is_dir( $file ) ) {
> $rand_image[] = $file;
> }
> }
> closedir( $handle );
> }
> }
> return $rand_image;
> }
>
> function MakeSuperRandom()
> {
> return srand( ( double ) microtime( time() ) * 100000 );
> }
>
> function PickRandomImages( $array )
> {
> $num1 = count( $array );
> $num1 = $num1 - 1;
> MakeSuperRandom();
>
> $img_num = rand( 3, $num1 );
> $image[] = $array[$img_num];
>
> $num2 = count( $array );
> $num2 = $num2 - 1;
> MakeSuperRandom();
>
> $img_num = rand( 3, $num2 );
> $image[] = $array[$img_num];
>
> $num3 = count( $array );
> $num3 = $num3 - 1;
> MakeSuperRandom();
>
> $img_num = rand( 3, $num3 );
> $image[] = $array[$img_num];
> return $image;
> }
>
> function ChkArray( $array )
> {
> if( ( empty( $array ) ) || ( count( $array ) > 3 ) ) {
> $data = 1;
> } else {
> $data = 0;
> }
> return $data;
> }
>
> function GeneratePrivKey( $array )
> {
> if( empty( $array ) ) {
> $data = GenerateError( "Missing data for GeneratePrivKey function." );
> } else {
> for( $x = 0; $x < count( $array ); $x++ ) {
> $keys[] = mhash( MHASH_SHA1, sha1( $array[$x] ) );
> }
> for( $y = 0; $y < count( $keys ); $y++ ) {
> if( count( $keys ) == $keys[$y] ) {
> $data .= $keys[$y];
> } else {
> $data .= $keys[$y] . ":";
> }
> }
> }
> return $data;
> }
>
> function GeneratePubKey( $data )
> {
> return md5( $data );
> }
>
> function EncData( $data, $key )
> {
> $td = mcrypt_module_open( 'rijndael-256', '', 'ofb', '' );
> $iv = mcrypt_create_iv( mcrypt_enc_get_iv_size( $td ), MCRYPT_DEV_RANDOM );
> $ks = mcrypt_enc_get_key_size( $td );
> @mcrypt_generic_init( $td, $key, $iv );
> $encrypted = mcrypt_generic( $td, $data );
> echo "<br><b>Ciphered Text using Random Image Hash as Key:</b><pre> " .
> $encrypted . "</pre><br>";
> @mcrypt_generic_deinit( $td );
> @mcrypt_generic_init( $td, $key, $iv );
> $decrypted = mdecrypt_generic( $td, $encrypted );
> echo "<br><b>De-Ciphered Text using Random Image Hash as Key:</b><pre>"
> . $decrypted . "</pre>";
> @mcrypt_generic_deinit( $td );
> @mcrypt_module_close( $td );
> }
>
> // to use functions
> $x = ReadFolder( "images/" );
> $y = PickRandomImages( $x );
> $b = GeneratePrivKey( $y );
> echo "<b>Private Key data:</b><pre>" . $b . "</pre>";
> $data = "<br>" . GeneratePubKey( $b );
> echo "<b>Public Key data:</b><pre>"; print_r( $data ); echo "</pre>";
> echo EncData( $credit_card_data, $b );
>
> ?>
>
> With that code you will have to re-write the 'EncData()' function to
> perform ONLY encryption as of right now it encrypts and decrypts for
> demonstration purposes only.
>
> And on another note why not use a different delivery method altogether
> such as using java-script to encrypt the data prior to transmission,
> store the private key inside the local network, use the public key and
> associate it with the purchase within the database and develop a method
> of authentication for the users to retrieve the data and then, and only
> then use the private key to decrypt the data.
>
My apologies, I just noticed you did mention a database for storage. SSL
would probably work better then java-script. Hell if you really wanted
to secure the data prior to transmission using flash might help obscure
the data and give you a good method of assigning a unique private/public
key as well as passing it through your cipher prior to transmission.
The kerberos authentication protocol does a similar method prior to
sending the data which is always the most secure against eves droppers
and man in the middle attacks.
> Just a thought.
>
>> case, I wrote an algorithm that would encrypt these digits prior to
>> sending, using the actual order number as a key. The accounting
>> software I wrote (all in PHP) would then retrieve the latter half of
>> the credit card number from the database, decrypt the first part of
>> the credit card number from the email (entered by the sales team on an
>> SSL-encrypted page), and the credit card number would be displayed in
>> full on the screen, to print, process, or verify.
>
>> The downside is that, if there are any problems with email and
>> delivery, the first $n digits of the card might not be received by the
>> sales department. While, to date, I'm not aware of this having been a
>> problem for my client (knock on wood), it's still a possibility. For
>> this reason, you need to be sure to either have the email address
>> confirmed prior to processing the order, or require a valid telephone
>> number, so that you can reach the customer in the event of a failure.
>> To assure the customer that you are calling legitimately, you will
>> still have the last digits of the credit card, as well as the
>> expiration data and CVV number (also stored in the database), the
>> billing address, and the date and time the order was placed.
>
>> It may not work for you, but that's how I created the system for
>> my client in 2004, and it's still being used today, with almost $8
>> Million in online sales. [pats self on back] ;-P
>
>> Now if I could just go back and renegotiate my contract for that gig....
>
>
>
- --
Jason Gerfen
"I practice my religion
while stepping on your
toes..."
~The Ditty Bops
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