convert value to hex for storage and back for display

<?php

// http://www.gravityhelp.com/forums/topic/input-on-single-line-text-is-cut-off-after
// this handles converting the entered value to hex for storage
//
// strtohex and hextostr functions lifted from here:
// http://www.php.net/manual/en/function.hexdec.php#100578
//
// change the 60 here to your form ID
add_filter('gform_pre_submission_filter_60', 'ch_strtohex');
function ch_strtohex($form) {
    // input 4 is the form field I want to convert to hex
    $x = rgpost('input_4');
    $s='';
    // convert the submitted string to hex
    foreach(str_split($x) as $c)
        $s .= sprintf('%02X',ord($c));
    // assign the hex value to the POST field
    $_POST['input_4'] = $s;
    // return the form
    return $form;
}

// http://www.gravityhelp.com/forums/topic/input-on-single-line-text-is-cut-off-after
// retrieve hex and convert before displaying in the admin: single entry view
add_filter('gform_entry_field_value', 'ch_hextostr_single', 10, 4);
function ch_hextostr_single($x, $field, $lead, $form) {
    // run this code on form 60, field 4 only
    // change to match your form values
    if ($form['id'] == 60 && $field['id'] == 4) {
        $s='';
        foreach(explode("\n",trim(chunk_split($x,2))) as $h) {
            $s .= chr(hexdec($h));
        }
        // prevent rendering anything that looks like HTML as HTML
        return htmlspecialchars($s);
    }
    else {
        // not (form 60 and field 4), return the original value
        return $x;
    }
}

// http://www.gravityhelp.com/forums/topic/input-on-single-line-text-is-cut-off-after
// retrieve hex and convert before displaying in the admin: entry list view
// note the different filter name here "entries"
add_filter('gform_entries_field_value', 'ch_hextostr_list', 10, 3);
function ch_hextostr_list($x, $form_id, $field_id) {
    // run this code on form 60, field 4 only
    // change to match your form values
    if ($form_id == 60 && $field_id == 4) {
        $s='';
        foreach(explode("\n",trim(chunk_split($x,2))) as $h) {
            $s .= chr(hexdec($h));
        }
        // prevent rendering anything that looks like HTML as HTML
        return htmlspecialchars($s);
    }
    else {
        // not (form 60 and field 4), return the original value
        return $x;
    }
}