wpa_write.php

<?php 

$ssid = "my_ssid";
$network['passphrase'] = "my_passphrase";
$wpa_file = fopen('/tmp/wifidata', 'w');

if (strlen($network['passphrase']) >=8 && strlen($network['passphrase']) <= 63) {
    unset($wpa_passphrase);
    unset($line);
    exec('wpa_passphrase '. ssid2utf8( escapeshellarg($ssid) ) . ' ' . escapeshellarg($network['passphrase']), $wpa_passphrase);
    foreach ($wpa_passphrase as $line) {
        if (preg_match('/^\s*}\s*$/', $line)) {
            if (array_key_exists('priority', $network)) {
                fwrite($wpa_file, "\tpriority=".$network['priority'].PHP_EOL);
            }
            fwrite($wpa_file, $line.PHP_EOL);
        } else {
            if ( preg_match('/\\\\x[0-9A-Fa-f]{2}/',$ssid) && strpos($line, "ssid=\"") !== false ) {
                 fwrite($wpa_file, "\tssid=P\"".$ssid."\"".PHP_EOL);
            } else {
                 fwrite($wpa_file, $line.PHP_EOL);
            }
        }
    }
} else {
    echo 'WPA passphrase must be between 8 and 63 characters';
}

/*
 * Replace escaped bytes (hex) by binary - assume UTF8 encoding
 *
 * @param string $ssid
 */
function ssid2utf8($ssid)
{
    return  evalHexSequence($ssid);
}

// Sanitizes a string for QR encoding
// @param string $str
// @return string
function qr_encode($str)
{
    return preg_replace('/(?<!\\\)([\":;,])/', '\\\\\1', $str);
}

function evalHexSequence($string)
{
    $evaluator = function ($input) {
	return hex2bin($input[1]);
    };
    return preg_replace_callback('/\\\x(..)/', $evaluator, $string);
}
?>