public function DKIM_Sign($signHeader)
{
if (!defined('PKCS7_TEXT')) {
if ($this->exceptions) {
throw new phpmailerException($this->lang('extension_missing') . 'openssl');
}
return '';
}
$privKeyStr = !empty($this->DKIM_private_string) ? $this->DKIM_private_string : file_get_contents($this->DKIM_private);
if ('' != $this->DKIM_passphrase) {
$privKey = openssl_pkey_get_private($privKeyStr, $this->DKIM_passphrase);
} else {
$privKey = openssl_pkey_get_private($privKeyStr);
}
//Workaround for missing digest algorithms in old PHP & OpenSSL versions
//@link http://stackoverflow.com/a/11117338/333340
if (version_compare(PHP_VERSION, '5.3.0') >= 0 and in_array('sha256WithRSAEncryption', openssl_get_md_methods(true))) {
if (openssl_sign($signHeader, $signature, $privKey, 'sha256WithRSAEncryption')) {
openssl_pkey_free($privKey);
return base64_encode($signature);
}
} else {
$pinfo = openssl_pkey_get_details($privKey);
$hash = hash('sha256', $signHeader);
//'Magic' constant for SHA256 from RFC3447
//@link https://tools.ietf.org/html/rfc3447#page-43
$t = '3031300d060960864801650304020105000420' . $hash;
$pslen = $pinfo['bits'] / 8 - (strlen($t) / 2 + 3);
$eb = pack('H*', '0001' . str_repeat('FF', $pslen) . '00' . $t);
if (openssl_private_encrypt($eb, $signature, $privKey, OPENSSL_NO_PADDING)) {
openssl_pkey_free($privKey);
return base64_encode($signature);
}
}
openssl_pkey_free($privKey);
return '';
}