Access Denied for ListObjects AWS STS and S3 Client - php

Question

I am unable to use the method ListObjects to access AWS S3 using the Secure Token Service.
The documentation states a bucket and it's object can be private, while we can use AWS STS to gain temporary credentials to access the S3 objects.
I am attempting to create a Graphics Server. I have a separate service that you can query. During the response, my plan is to use AWS STS to expose the images in my S3 bucket.
use Aws\Sts\StsClient;
use Aws\S3\S3Client;
use Aws\S3\Exception\S3Exception;
$bucket = 'bucket_name';
// the security credentials that you use to obtain temporary security credentials.
$stsClient = StsClient::factory(array(
'credentials' => array(
'secret' => 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX',
'key' => 'YYYYYYYYYYYYYYYYYYYYYYYYY'
),
'region'=>'us-east-1',
'version'=>'latest'
));
// Fetch the federated credentials.
$sessionToken = $stsClient->getFederationToken([
'Name' => 'IAM-Username',
'DurationSeconds' => '3600',
'PolicyName' => 'my-policy'
]);
// The following will be part of your less trusted code. You provide temporary
// security credentials so the code can send authenticated requests to Amazon S3.
$s3 = new S3Client([
'region' => 'us-east-1',
'version' => 'latest',
'credentials' => [
'key' => $sessionToken['Credentials']['AccessKeyId'],
'secret' => $sessionToken['Credentials']['SecretAccessKey'],
'token' => $sessionToken['Credentials']['SessionToken']
]
]);
print_r($sessionToken);
echo "<br/>";
echo "<br/>";
try {
$result = $s3->listObjects([
'Bucket' => $bucket
]);
} catch (S3Exception $e) {
echo $e->getMessage() . PHP_EOL;
}
I was expecting a list of S3 Object Keys. But instead I get an error message:
Error executing "ListObjects" on "https://s3.amazonaws.com/bucket_name?encoding-type=url"; AWS HTTP error: Client error: GET
https://s3.amazonaws.com/bucket_name?encoding-type=url resulted in a 403 >Forbidden response: AccessDeniedAccess Denied AccessDenied (client): >Access Denied - AccessDeniedAccess Denied XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Answer 1

found my answer. I was calling the wrong method.
I changed this:
$sessionToken = $stsClient->getFederationToken([
'Name' => 'IAM-Username',
'DurationSeconds' => '3600',
'PolicyName' => 'my-policy'
]);
to this:
$sessionToken = $stsClient->getSessionToken([
'Name' => 'IAM-Username',
'DurationSeconds' => '3600',
'PolicyName' => 'my-policy'
]);
use getSessionToken instead of getFederationToken, which is kinda obvious.