I have coded a simple test, but it sent me: "Unverified", I guess because I am using the whole certificate instead of the public key. What method gives me public key?
$rsa = new Crypt_RSA();
$rsa->setPassword('here I include password');
$rsa->loadKey(file_get_contents('i.pem')); // private key
$plaintext = 'abc';
$rsa->setSignatureMode(CRYPT_RSA_SIGNATURE_PKCS1);
$signature = $rsa->sign($plaintext);
//now the verification
$rsa->loadKey(file_get_contents('instancia_ope.crt')); //here maybe WRONG
echo $rsa->verify($plaintext, $signature) ? 'Verified' : 'Unverified';