openSSL rsa_padding_mode:pss be emulated with phpseclib: RSA - phpseclib

Question

How can this openSSL command be emulated with phpseclib: RSA
openssl pkeyutl -verify -in gfeHmac.bin -sigfile privkey2_140225_gfesig.bin -pubin -inkey pubkey2_140225.pem -pkeyopt digest:sha256 -pkeyopt rsa_padding_mode:pss -pkeyopt rsa_pss_saltlen:-1
Here is the basic php stub that fails to verify:
include('phpseclib0.3.6/Math/BigInteger.php');
include('phpseclib0.3.6/Crypt/Hash.php');
include('phpseclib0.3.6/Crypt/TripleDES.php');
include('phpseclib0.3.6/Crypt/RSA.php');
echo "<hr>Using: phpseclib0.3.6/Crypt/RSA.php<br>";
function getCrntRsaPbKey()
{
return "-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDmA6xcIcBo0UiVxzduHFjks511
R5Y+gsvn6rVyjIWSQZt0h8N8vJPreDCDcOybToFmJMnz8R8aohC6ipJ0nIaI644+
oXVQkKGEjaAFKn+L6AEUQSZKkkbmEjBqDSriq91q8U78Ky6xT5a5JpuHz+QEgGi2
SXf1t3EBec1vjgMycQIDAQAB
-----END PUBLIC KEY-----";
} // private function getCrntRsaPbKey($incoming)
$origData = "4hZpNOnmgAlqkCCLMJ8MKv1pC73aTReA7Pht4hnc4Os=";
echo "<hr>original base64 hash payLoad:";
var_dump ( $origData );
$signedUsePrv = "Rzwo6eiCDf/w7f69JcKuq7a0czlAXuLXsgJbat2GRc6Tvv3CH04/ccpOZoV2+NKA5tew1QH3Ic+M
qhYJkRA5l+bK6RIuEuxQ8Eo5qSpxBHmmup41INTiR4xRB2KSp+uNgj2Nw2+GAmfpK+nx53sXcxkD
ZnB+njlJTkuhx4iKmM8=";
echo "<hr>original signed digest base64 payLoad:";
var_dump ( $signedUsePrv );
$rsa = new Crypt_RSA();
//$rsa->setMGFHash('sha256');
$rsa->setHash('sha256');
//echo "<hr>\$rsa->setHash('sha256')";var_dump($tst);
//$rsa->setPublicKeyFormat(CRYPT_RSA_PUBLIC_FORMAT_PKCS1);
//$rsa->setPrivateKeyFormat(CRYPT_RSA_PRIVATE_FORMAT_PKCS1);
//$rsa->setSignatureMode(CRYPT_RSA_SIGNATURE_PSS);
//$rsa->setSaltLength(-1);
echo "<hr>\$rsa:";var_dump ( $rsa );
$pubKey = getCrntRsaPbKey();
echo ("<hr>publickeytest can load<br>" . $pubKey);
$rsaLoadKeyRslt = $rsa->loadKey(($pubKey));
echo "<br>\$rsa->loadKey(\$pubKey):";var_dump ( $rsaLoadKeyRslt );
$rsaVerifyRslt = $rsa->verify ( base64_decode ( $origData ), ( $signedUsePrv ) );
echo "<hr>\$rsa->verify with Eric provided public and signature file:";var_dump ( $rsaVerifyRslt );
if ($rsaVerifyRslt==1)
{
echo "<br>isSigned true , using Remotely Signed signature";
}

Answer 1

phpseclib uses PSS by default for signature verification and uses a salt length of -1 by default as well (well it uses a salt length equal to the hash length which is what the -1 means I think).
The only thing from that that's different than what phpseclib is doing by default is that it's using sha256 whereas phpseclib uses sha1 by default.
Anyway in light of that I think this'll do what you're wanting:
<?php
include('Crypt/RSA.php');
$rsa = new Crypt_RSA();
$rsa->loadKey(file_get_contents('privatekey.txt'));
$rsa->loadKey($rsa->getPublicKey());
$rsa->setHash('sha256');
$rsa->setMGFHash('sha256');
echo $rsa->verify(
file_get_contents('plaintext.txt'),
file_get_contents('signature.txt')
) ? 'verified' : 'unverified';