diff --git a/CHANGELOG.md b/CHANGELOG.md
index 15bb1b1f..bda29706 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@
     * CHANGED: Avoid `SUPER` privilege for setting the `sql_mode` for MariaDB/MySQL (#919)
     * FIXED: Revert to CREATE INDEX without IF NOT EXISTS clauses, to support MySQL (#943)
     * FIXED: Apply table prefix to indexes as well, to support multiple instances sharing a single database (#943)
+    * ADDED: S3 Storage backend (#994)
   * **1.4 (2022-04-09)**
     * ADDED: Translations for Corsican, Estonian, Finnish and Lojban
     * ADDED: new HTTP headers improving security (#765)
diff --git a/CREDITS.md b/CREDITS.md
index c0be0ad2..d0035077 100644
--- a/CREDITS.md
+++ b/CREDITS.md
@@ -29,6 +29,7 @@
 * rodehoed - option to exempt ips from the rate-limiter
 * Mark van Holsteijn - Google Cloud Storage backend
 * Austin Huang - Oracle database support
+* Felix J. Ogris - S3 Storage backend
 
 ## Translations
 * Hexalyse - French
@@ -58,4 +59,4 @@
 * Markus Mikkonen - Finnish
 * Emir Ensar Rahmanlar - Turkish
 * Stevo984 - Slovak
-* Christos Karamolegkos - Greek
\ No newline at end of file
+* Christos Karamolegkos - Greek
diff --git a/INSTALL.md b/INSTALL.md
index 615ce56e..f35d68bf 100644
--- a/INSTALL.md
+++ b/INSTALL.md
@@ -232,3 +232,42 @@ Platform using Google Cloud Run is easy and cheap.
 
 To use the Google Cloud Storage backend you have to install the suggested
 library using the command `composer require google/cloud-storage`.
+
+#### Using S3 Storage
+Similar to Google Cloud Storage, you can choose S3 as storage backend. It uses
+the AWS SDK for PHP, but can also talk to a Rados gateway as part of a CEPH
+cluster. To use this backend, you first have to install the SDK in the
+document root of PrivateBin: `composer require aws/aws-sdk-php`. You have to
+create the S3 bucket on the CEPH cluster before using the S3 backend.
+
+In the `[model]` section of cfg/conf.php, set `class` to `S3Storage`.
+
+You can set any combination of the following options in the `[model_options]`
+section:
+
+  * region
+  * version
+  * endpoint
+  * bucket
+  * prefix
+  * accesskey
+  * secretkey
+  * use_path_style_endpoint
+
+By default, prefix is empty. If set, the S3 backend will place all PrivateBin
+data beneath this prefix.
+
+For AWS, you have to provide at least `region`, `bucket`, `accesskey`, and
+`secretkey`.
+
+For CEPH, follow this example:
+
+```
+region = ""
+version = "2006-03-01"
+endpoint = "https://s3.my-ceph.invalid"
+use_path_style_endpoint = true
+bucket = "my-bucket"
+accesskey = "my-rados-user"
+secretkey = "my-rados-pass"
+```
diff --git a/cfg/conf.sample.php b/cfg/conf.sample.php
index ab37da7b..cf465980 100644
--- a/cfg/conf.sample.php
+++ b/cfg/conf.sample.php
@@ -205,3 +205,25 @@ dir = PATH "data"
 ;usr = "privatebin"
 ;pwd = "Z3r0P4ss"
 ;opt[12] = true    ; PDO::ATTR_PERSISTENT
+
+;[model]
+; example of S3 configuration for Rados gateway / CEPH
+;class = S3Storage
+;[model_options]
+;region = ""
+;version = "2006-03-01"
+;endpoint = "https://s3.my-ceph.invalid"
+;use_path_style_endpoint = true
+;bucket = "my-bucket"
+;accesskey = "my-rados-user"
+;secretkey = "my-rados-pass"
+
+;[model]
+; example of S3 configuration for AWS
+;class = S3Storage
+;[model_options]
+;region = "eu-central-1"
+;version = "latest"
+;bucket = "my-bucket"
+;accesskey = "access key id"
+;secretkey = "secret access key"
diff --git a/composer.json b/composer.json
index 0fd34559..01d384f2 100644
--- a/composer.json
+++ b/composer.json
@@ -30,7 +30,8 @@
 		"mlocati/ip-lib" : "1.18.0"
 	},
 	"suggest" : {
-		"google/cloud-storage" : "1.26.1"
+		"google/cloud-storage" : "1.26.1",
+		"aws/aws-sdk-php" : "3.239.0"
 	},
 	"require-dev" : {
 		"phpunit/phpunit" : "^4.6 || ^5.0"
diff --git a/lib/Configuration.php b/lib/Configuration.php
index 9f4e35f7..fad44a27 100644
--- a/lib/Configuration.php
+++ b/lib/Configuration.php
@@ -157,6 +157,22 @@ class Configuration
                     'prefix'     => 'pastes',
                     'uniformacl' => false,
                 );
+            } elseif (
+                $section == 'model_options' && in_array(
+                    $this->_configuration['model']['class'],
+                    array('S3Storage')
+                )
+            ) {
+                $values = array(
+                    'region'                  => null,
+                    'version'                 => null,
+                    'endpoint'                => null,
+                    'accesskey'               => null,
+                    'secretkey'               => null,
+                    'use_path_style_endpoint' => null,
+                    'bucket'                  => null,
+                    'prefix'                  => '',
+                );
             }
 
             // "*_options" sections don't require all defaults to be set
diff --git a/lib/Data/S3Storage.php b/lib/Data/S3Storage.php
new file mode 100644
index 00000000..d741e099
--- /dev/null
+++ b/lib/Data/S3Storage.php
@@ -0,0 +1,464 @@
+<?php
+/**
+ * S3.php
+ *
+ * an S3 compatible data backend for PrivateBin with CEPH/RadosGW in mind
+ * see https://docs.ceph.com/en/latest/radosgw/s3/php/
+ * based on lib/Data/GoogleCloudStorage.php from PrivateBin version 1.4.0
+ *
+ * @link      https://github.com/PrivateBin/PrivateBin
+ * @copyright 2022 Felix J. Ogris (https://ogris.de/)
+ * @license   https://www.opensource.org/licenses/zlib-license.php The zlib/libpng License
+ * @version   1.4.1
+ *
+ * Installation:
+ *   1. Make sure you have composer.lock and composer.json in the document root of your PasteBin
+ *   2. If not, grab a copy from https://github.com/PrivateBin/PrivateBin
+ *   3. As non-root user, install the AWS SDK for PHP:
+ *      composer require aws/aws-sdk-php
+ *      (On FreeBSD, install devel/php-composer2 prior, e.g.: make -C /usr/ports/devel/php-composer2 install clean)
+ *   4. In cfg/conf.php, comment out all [model] and [model_options] settings
+ *   5. Still in cfg/conf.php, add a new [model] section:
+ *      [model]
+ *      class = S3Storage
+ *   6. Add a new [model_options] as well, e.g. for a Rados gateway as part of your CEPH cluster:
+ *      [model_options]
+ *      region = ""
+ *      version = "2006-03-01"
+ *      endpoint = "https://s3.my-ceph.invalid"
+ *      use_path_style_endpoint = true
+ *      bucket = "my-bucket"
+ *      prefix = "privatebin"  (place all PrivateBin data beneath this prefix)
+ *      accesskey = "my-rados-user"
+ *      secretkey = "my-rados-pass"
+ */
+
+namespace PrivateBin\Data;
+
+use Aws\S3\Exception\S3Exception;
+use Aws\S3\S3Client;
+use PrivateBin\Json;
+
+class S3Storage extends AbstractData
+{
+    /**
+     * S3 client
+     *
+     * @access private
+     * @static
+     * @var    S3Client
+     */
+    private static $_client = null;
+
+    /**
+     * S3 client options
+     *
+     * @access private
+     * @static
+     * @var    array
+     */
+    private static $_options = array();
+
+    /**
+     * S3 bucket
+     *
+     * @access private
+     * @static
+     * @var    string
+     */
+    private static $_bucket = null;
+
+    /**
+     * S3 prefix for all PrivateBin data in this bucket
+     *
+     * @access private
+     * @static
+     * @var    string
+     */
+    private static $_prefix = '';
+
+    /**
+     * returns an S3 data backend.
+     *
+     * @access public
+     * @static
+     * @param array $options
+     * @return S3Storage
+     */
+    public static function getInstance(array $options)
+    {
+        // if needed initialize the singleton
+        if (!(self::$_instance instanceof self)) {
+            self::$_instance = new self;
+        }
+
+        self::$_options                = array();
+        self::$_options['credentials'] = array();
+
+        if (is_array($options) && array_key_exists('region', $options)) {
+            self::$_options['region'] = $options['region'];
+        }
+        if (is_array($options) && array_key_exists('version', $options)) {
+            self::$_options['version'] = $options['version'];
+        }
+        if (is_array($options) && array_key_exists('endpoint', $options)) {
+            self::$_options['endpoint'] = $options['endpoint'];
+        }
+        if (is_array($options) && array_key_exists('accesskey', $options)) {
+            self::$_options['credentials']['key'] = $options['accesskey'];
+        }
+        if (is_array($options) && array_key_exists('secretkey', $options)) {
+            self::$_options['credentials']['secret'] = $options['secretkey'];
+        }
+        if (is_array($options) && array_key_exists('use_path_style_endpoint', $options)) {
+            self::$_options['use_path_style_endpoint'] = filter_var($options['use_path_style_endpoint'], FILTER_VALIDATE_BOOLEAN);
+        }
+        if (is_array($options) && array_key_exists('bucket', $options)) {
+            self::$_bucket = $options['bucket'];
+        }
+        if (is_array($options) && array_key_exists('prefix', $options)) {
+            self::$_prefix = $options['prefix'];
+        }
+
+        if (empty(self::$_client)) {
+            self::$_client = new S3Client(self::$_options);
+        }
+
+        return self::$_instance;
+    }
+
+    /**
+     * returns all objects in the given prefix.
+     *
+     * @access private
+     * @param $prefix string with prefix
+     * @return array all objects in the given prefix
+     */
+    private function _listAllObjects($prefix)
+    {
+        $allObjects = array();
+        $options    = array(
+            'Bucket' => self::$_bucket,
+            'Prefix' => $prefix,
+        );
+
+        do {
+            $objectsListResponse = self::$_client->listObjects($options);
+            $objects             = $objectsListResponse['Contents'] ?? array();
+            foreach ($objects as $object) {
+                $allObjects[]      = $object;
+                $options['Marker'] = $object['Key'];
+            }
+        } while ($objectsListResponse['IsTruncated']);
+
+        return $allObjects;
+    }
+
+    /**
+     * returns the S3 storage object key for $pasteid in self::$_bucket.
+     *
+     * @access private
+     * @param $pasteid string to get the key for
+     * @return string
+     */
+    private function _getKey($pasteid)
+    {
+        if (self::$_prefix != '') {
+            return self::$_prefix . '/' . $pasteid;
+        }
+        return $pasteid;
+    }
+
+    /**
+     * Uploads the payload in the self::$_bucket under the specified key.
+     * The entire payload is stored as a JSON document. The metadata is replicated
+     * as the S3 object's metadata except for the fields attachment, attachmentname
+     * and salt.
+     *
+     * @param $key string to store the payload under
+     * @param $payload array to store
+     * @return bool true if successful, otherwise false.
+     */
+    private function _upload($key, $payload)
+    {
+        $metadata = array_key_exists('meta', $payload) ? $payload['meta'] : array();
+        unset($metadata['attachment'], $metadata['attachmentname'], $metadata['salt']);
+        foreach ($metadata as $k => $v) {
+            $metadata[$k] = strval($v);
+        }
+        try {
+            self::$_client->putObject(array(
+                'Bucket'      => self::$_bucket,
+                'Key'         => $key,
+                'Body'        => Json::encode($payload),
+                'ContentType' => 'application/json',
+                'Metadata'    => $metadata,
+            ));
+        } catch (S3Exception $e) {
+            error_log('failed to upload ' . $key . ' to ' . self::$_bucket . ', ' .
+                trim(preg_replace('/\s\s+/', ' ', $e->getMessage())));
+            return false;
+        }
+        return true;
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function create($pasteid, array $paste)
+    {
+        if ($this->exists($pasteid)) {
+            return false;
+        }
+
+        return $this->_upload($this->_getKey($pasteid), $paste);
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function read($pasteid)
+    {
+        try {
+            $object = self::$_client->getObject(array(
+                'Bucket' => self::$_bucket,
+                'Key'    => $this->_getKey($pasteid),
+            ));
+            $data = $object['Body']->getContents();
+            return Json::decode($data);
+        } catch (S3Exception $e) {
+            error_log('failed to read ' . $pasteid . ' from ' . self::$_bucket . ', ' .
+                trim(preg_replace('/\s\s+/', ' ', $e->getMessage())));
+            return false;
+        }
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function delete($pasteid)
+    {
+        $name = $this->_getKey($pasteid);
+
+        try {
+            $comments = $this->_listAllObjects($name . '/discussion/');
+            foreach ($comments as $comment) {
+                try {
+                    self::$_client->deleteObject(array(
+                        'Bucket' => self::$_bucket,
+                        'Key'    => $comment['Key'],
+                    ));
+                } catch (S3Exception $e) {
+                    // ignore if already deleted.
+                }
+            }
+        } catch (S3Exception $e) {
+            // there are no discussions associated with the paste
+        }
+
+        try {
+            self::$_client->deleteObject(array(
+                'Bucket' => self::$_bucket,
+                'Key'    => $name,
+            ));
+        } catch (S3Exception $e) {
+            // ignore if already deleted
+        }
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function exists($pasteid)
+    {
+        return self::$_client->doesObjectExistV2(self::$_bucket, $this->_getKey($pasteid));
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function createComment($pasteid, $parentid, $commentid, array $comment)
+    {
+        if ($this->existsComment($pasteid, $parentid, $commentid)) {
+            return false;
+        }
+        $key = $this->_getKey($pasteid) . '/discussion/' . $parentid . '/' . $commentid;
+        return $this->_upload($key, $comment);
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function readComments($pasteid)
+    {
+        $comments = array();
+        $prefix   = $this->_getKey($pasteid) . '/discussion/';
+        try {
+            $entries = $this->_listAllObjects($prefix);
+            foreach ($entries as $entry) {
+                $object = self::$_client->getObject(array(
+                    'Bucket' => self::$_bucket,
+                    'Key'    => $entry['Key'],
+                ));
+                $body             = JSON::decode($object['Body']->getContents());
+                $items            = explode('/', $entry['Key']);
+                $body['id']       = $items[3];
+                $body['parentid'] = $items[2];
+                $slot             = $this->getOpenSlot($comments, (int) $object['Metadata']['created']);
+                $comments[$slot]  = $body;
+            }
+        } catch (S3Exception $e) {
+            // no comments found
+        }
+        return $comments;
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function existsComment($pasteid, $parentid, $commentid)
+    {
+        $name = $this->_getKey($pasteid) . '/discussion/' . $parentid . '/' . $commentid;
+        return self::$_client->doesObjectExistV2(self::$_bucket, $name);
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function purgeValues($namespace, $time)
+    {
+        $path = self::$_prefix;
+        if ($path != '') {
+            $path .= '/';
+        }
+        $path .= 'config/' . $namespace;
+
+        try {
+            foreach ($this->_listAllObjects($path) as $object) {
+                $name = $object['Key'];
+                if (strlen($name) > strlen($path) && substr($name, strlen($path), 1) !== '/') {
+                    continue;
+                }
+                $head = self::$_client->headObject(array(
+                    'Bucket' => self::$_bucket,
+                    'Key'    => $name,
+                ));
+                if (array_key_exists('Metadata', $head) && array_key_exists('value', $head['Metadata'])) {
+                    $value = $head['Metadata']['value'];
+                    if (is_numeric($value) && intval($value) < $time) {
+                        try {
+                            self::$_client->deleteObject(array(
+                                'Bucket' => self::$_bucket,
+                                'Key'    => $name,
+                            ));
+                        } catch (S3Exception $e) {
+                            // deleted by another instance.
+                        }
+                    }
+                }
+            }
+        } catch (S3Exception $e) {
+            // no objects in the bucket yet
+        }
+    }
+
+    /**
+     * For S3, the value will also be stored in the metadata for the
+     * namespaces traffic_limiter and purge_limiter.
+     * @inheritDoc
+     */
+    public function setValue($value, $namespace, $key = '')
+    {
+        $prefix = self::$_prefix;
+        if ($prefix != '') {
+            $prefix .= '/';
+        }
+
+        if ($key === '') {
+            $key = $prefix . 'config/' . $namespace;
+        } else {
+            $key = $prefix . 'config/' . $namespace . '/' . $key;
+        }
+
+        $metadata = array('namespace' => $namespace);
+        if ($namespace != 'salt') {
+            $metadata['value'] = strval($value);
+        }
+        try {
+            self::$_client->putObject(array(
+                'Bucket'      => self::$_bucket,
+                'Key'         => $key,
+                'Body'        => $value,
+                'ContentType' => 'application/json',
+                'Metadata'    => $metadata,
+            ));
+        } catch (S3Exception $e) {
+            error_log('failed to set key ' . $key . ' to ' . self::$_bucket . ', ' .
+                trim(preg_replace('/\s\s+/', ' ', $e->getMessage())));
+            return false;
+        }
+        return true;
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function getValue($namespace, $key = '')
+    {
+        $prefix = self::$_prefix;
+        if ($prefix != '') {
+            $prefix .= '/';
+        }
+
+        if ($key === '') {
+            $key = $prefix . 'config/' . $namespace;
+        } else {
+            $key = $prefix . 'config/' . $namespace . '/' . $key;
+        }
+
+        try {
+            $object = self::$_client->getObject(array(
+                'Bucket' => self::$_bucket,
+                'Key'    => $key,
+            ));
+            return $object['Body']->getContents();
+        } catch (S3Exception $e) {
+            return '';
+        }
+    }
+
+    /**
+     * @inheritDoc
+     */
+    protected function _getExpiredPastes($batchsize)
+    {
+        $expired = array();
+        $now     = time();
+        $prefix  = self::$_prefix;
+        if ($prefix != '') {
+            $prefix .= '/';
+        }
+
+        try {
+            foreach ($this->_listAllObjects($prefix) as $object) {
+                $head = self::$_client->headObject(array(
+                    'Bucket' => self::$_bucket,
+                    'Key'    => $object['Key'],
+                ));
+                if (array_key_exists('Metadata', $head) && array_key_exists('expire_date', $head['Metadata'])) {
+                    $expire_at = intval($head['Metadata']['expire_date']);
+                    if ($expire_at != 0 && $expire_at < $now) {
+                        array_push($expired, $object['Key']);
+                    }
+                }
+
+                if (count($expired) > $batchsize) {
+                    break;
+                }
+            }
+        } catch (S3Exception $e) {
+            // no objects in the bucket yet
+        }
+        return $expired;
+    }
+}