php - Supplied key param cannot be coerced into a private key with Google APIs

Question

I'm trying to test this example that I found here so that I can do a direct upload on the client side without having the user login using Google Cloud Storage.

All of the constants expressed have their correct values, and the path is correct and does not have an empty contents.

The error I'm getting:

openssl_sign(): supplied key param cannot be coerced into a private key

My function implemented is:

public static function storageURL( $id, $method = 'GET', $duration = 10 ) {
    $key = file_get_contents(self::KEY_FILE);
    $pkey = openssl_get_privatekey($key, 'notasecret');
    $expires = time( ) + $duration;
    $content_type = ($method == 'PUT') ? 'application/x-www-form-urlencoded' : ''; 
    $to_sign = ($method . "
" . 
    /* Content-MD5 */ "
" . 
    $content_type . "
" . 
    $expires . "
" . 
    '/'.self::BUCKET_NAME.'/' . $id); 
    $signature = '*Signature will go here*';
    if (!openssl_sign( $to_sign, $signature, $pkey, 'sha256' ))
    { 
        error_log( 'openssl_sign failed!' );
        $signature = '<failed>'; 
    } else { 
        $signature = urlencode( base64_encode( $signature ) ); 
    } 
    return ('https://'.self::BUCKET_NAME.'.commondatastorage.googleapis.com/' .
        $id .
        '?GoogleAccessId=' . self::SERVICE_ACCOUNT_NAME .
        '&Expires=' . $expires . '&Signature=' . $signature);
    }

Answer 1

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