My openstack temporary URL keeps being invalid - php

Question

I try to generate temporary URLs for my Openstack ObjectStorage in a PHP application.
I've followed their documentation but even their python example isn't working.
So far, here is my generator :
class TempUrlGenerator implements ITempUrlGenerator
{
//See https://docs.openstack.org/swift/latest/api/temporary_url_middleware.html for details.
public function generate(string $url, int $validity = 5): string
{
$timestamp = time() + ($validity * 60);
return sprintf(
'%s?temp_url_sig=%s&temp_url_expires=%s',
$url,
$this->generateSignature($url, $timestamp),
$timestamp
);
}
private function generateSignature(string $url, int $timestamp): string
{
$body = sprintf(
'%s\n%s\n%s',
'GET',
$timestamp,
$this->getPath($url)
);
return hash_hmac('sha1', $body, trim(getenv('OPENSTACK_TEMPURL_KEY')));
}
private function getPath(string $url): string
{
$exploded = explode('/v1/', $url);
return sprintf('/v1/%s', $exploded[1]);
}
}
URL is the whole, complete URL (https://myserver.host.com/v1/...), validity is the number of minutes I want to keep my URL valid.
Beside that, the env variable is my secret key. I've already checked using a HEAD call on my account and my containers that the key is, indeed, uploaded on them with the good header. (X-Account-Meta-Temp-URL-Key and X-Container-Meta-Temp-URL-Key).
I've also checked multiple examples and implementations.
Yet I keep getting 401 invalid temp url when I try them.
Do you have any clue why or how I can troubleshot that ? Maybe is there some kind of setting on our server to check ?
Regards,