openssl_verify , Warning: openssl_verify(): suppli

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Supplied key param cannot be coerced into a private key with Google APIs 2 answers

I have this error with this file:

<?php
// $data and $signature are assumed to contain the data and the signature

$signature = null;
$toSign = "C:/Users/User/Desktop/xampp/htdocs/docum.docx";

$fp = fopen("key.pem", "r");
$priv_key = fread($fp, 8192);
fclose($fp);
$pkeyid = openssl_get_privatekey($priv_key);

openssl_sign($toSign, $signature, $pkeyid);

openssl_free_key($pkeyid);
echo($signature);
// fetch public key from certificate and ready it
$fp = fopen("C:/Users/User/Desktop/xampp/htdocs/pubkey.der", "r");
$cert = fread($fp, 8192);
fclose($fp);
$pubkeyid = openssl_get_publickey($cert);

// state whether signature is okay or not
$ok = openssl_verify($toSign, $signature, $pubkeyid);
if ($ok == 1) {
    echo "good";
} elseif ($ok == 0) {
    echo "bad";
} else {
    echo "ugly, error checking signature";
}
// free the key from memory
openssl_free_key($pubkeyid);
?>

how can I fix this error ?`... I calculated the signature with the private key to the document, now I want to test it. at first I created two php files , the first one that signed the document , the second occurred ke me signing . I just do not know how to take the signature from the first documento.Ho decided to put it all together to try ... How can I fix ?

Are you absolutely certain that your public key file is shorter than 8192 bytes? If you're just looking to read a file into a variable use file_get_contents(), it's far simpler.
What did openssl_get_publickey($cert) return?
Based on the error you got it looks like OpenSSL expects PEM formatted keys, so you'll need to convert it.

Try:

function der2pem($der_data) {
   $pem = chunk_split(base64_encode($der_data), 64, "\n");
   $pem = "-----BEGIN CERTIFICATE-----\n".$pem."-----END CERTIFICATE-----\n";
   return $pem;
}

$cert = der2pem(file_get_contents('C:/Users/User/Desktop/xampp/htdocs/pubkey.der'));

if( ! $pubkeyid = openssl_get_publickey($cert) ) {
    throw new \Exception(openssl_error_string());
}