function _key_exchange()
{
if (!is_null($this->_key) || $this->_encryptMode == 0) {
return true;
}
$request = "phprpc_encrypt=true&phprpc_keylen={$this->_keylen}";
$result = $this->_post($request);
if (is_a($result, 'PHPRPC_Error')) {
return $result;
}
if (array_key_exists('phprpc_keylen', $result)) {
$this->_keylen = (int) $result['phprpc_keylen'];
} else {
$this->_keylen = 128;
}
if (array_key_exists('phprpc_encrypt', $result)) {
$encrypt = unserialize(base64_decode($result['phprpc_encrypt']));
PHPRPC::xxtea();
// require_once('xxtea.php');
$x = BigInt::random($this->_keylen - 1, true);
$key = BigInt::powmod(BigInt::dec2num($encrypt['y']), $x, BigInt::dec2num($encrypt['p']));
if ($this->_keylen == 128) {
$key = BigInt::num2str($key);
} else {
$key = pack('H*', md5(BigInt::num2dec($key)));
}
$this->_key = str_pad($key, 16, "", STR_PAD_LEFT);
$encrypt = BigInt::num2dec(BigInt::powmod(BigInt::dec2num($encrypt['g']), $x, BigInt::dec2num($encrypt['p'])));
$request = "phprpc_encrypt={$encrypt}";
$result = $this->_post($request);
if (is_a($result, 'PHPRPC_Error')) {
return $result;
}
} else {
$this->_key = NULL;
$this->_encryptMode = 0;
}
return true;
}