IDP-initiated Logout not working

Login and sp-initiated logout seems working, although I can see some errors related with mcrypt in the log:
Function mcrypt_module_open() is deprecated at
/var/www/html/nextcloud/apps/user_saml/3rdparty/vendor/onelogin/php-saml/extlib/xmlseclibs/xmlseclibs.php#319

IDP-initiated Logout is not working.

How is affecting the mcrypt errors? is there some workaround, or is it going to be solved?

Thanks

Steps to reproduce

1. Log in with SSO/SAML
2. Start a IDP-initiated Logout
3. Check logout is effective

Expected behaviour

Logout initiated from idp should result in a correct logout from the SP ( nextcloud ) server.

Actual behaviour

logout message is not processed correctly by user_saml at SP ( nextcloud ) server

Server configuration

Operating system:
CentOS Linux release 7.4.1708 (Core)

Web server:
httpd-2.4.6-67.el7.centos.2.x86_64

Database:
mariadb-server-5.5.56-2.el7.x86_64

PHP version:
php71w-mysqlnd-7.1.9-2.w7.x86_64
mod_php71w-7.1.9-2.w7.x86_64
php71w-imap-7.1.9-2.w7.x86_64
php71w-pecl-imagick-3.4.3-1.w7.x86_64
php71w-pdo-7.1.9-2.w7.x86_64
php71w-mcrypt-7.1.9-2.w7.x86_64
php71w-cli-7.1.9-2.w7.x86_64
php71w-mbstring-7.1.9-2.w7.x86_64
php71w-pspell-7.1.9-2.w7.x86_64
php71w-ldap-7.1.9-2.w7.x86_64
php71w-pear-1.10.4-1.w7.noarch
php71w-common-7.1.9-2.w7.x86_64
php71w-xml-7.1.9-2.w7.x86_64
php71w-gd-7.1.9-2.w7.x86_64
php71w-process-7.1.9-2.w7.x86_64

Nextcloud version: (see Nextcloud admin page)

• version: 12.0.3.3

Where did you install Nextcloud from:
https://download.nextcloud.com/server/releases/nextcloud-12.0.3.zip

List of activated apps:

If you have access to your command line run e.g.:
sudo -u www-data php occ app:list
from within your Nextcloud installation folder

Enabled:

• activity: 2.5.2
• bruteforcesettings: 1.0.2
• calendar: 1.5.5
• comments: 1.2.0
• dav: 1.3.0
• federatedfilesharing: 1.2.0
• federation: 1.2.0
• files: 1.7.2
• files_pdfviewer: 1.1.1
• files_sharing: 1.4.0
• files_texteditor: 2.4.1
• files_trashbin: 1.2.0
• files_versions: 1.5.0
• files_videoplayer: 1.1.0
• firstrunwizard: 2.1
• gallery: 17.0.0
• groupfolders: 1.1.0
• logreader: 2.0.0
• lookup_server_connector: 1.0.0
• nextcloud_announcements: 1.1
• notifications: 2.0.0
• oauth2: 1.0.5
• password_policy: 1.2.2
• provisioning_api: 1.2.0
• serverinfo: 1.2.0
• sharebymail: 1.2.0
• survey_client: 1.0.0
• systemtags: 1.2.0
• theming: 1.3.0
• twofactor_backupcodes: 1.1.1
• updatenotification: 1.2.0
• user_saml: 1.4.0
• workflowengine: 1.2.0
  Disabled:
• admin_audit
• encryption
• files_external
• user_external
• user_ldap

Nextcloud configuration:

If you have access to your command line run e.g.:
sudo -u www-data php occ config:list system
from within your Nextcloud installation folder

or

Insert your config.php content here
Make sure to remove all sensitive content such as passwords. (e.g. database password, passwordsalt, secret, smtp password, …)

{
"system": {
"instanceid": "oceiqlv2uuy3",
"passwordsalt": "REMOVED SENSITIVE VALUE",
"secret": "REMOVED SENSITIVE VALUE",
"trusted_domains": [
"ibox.ific.uv.es",
"triki.ific.uv.es",
"wn158.ific.uv.es",
"kantele.ific.uv.es"
],
"log_type": "owncloud",
"logfile": "nextcloud.log",
"loglevel": "0",
"datadirectory": "/var/www/html/nextcloud/data",
"overwrite.cli.url": "http://ibox.ific.uv.es/nextcloud",
"dbtype": "mysql",
"version": "12.0.3.3",
"dbname": "nextcloud",
"dbhost": "localhost",
"dbport": "",
"dbtableprefix": "oc_",
"dbuser": "REMOVED SENSITIVE VALUE",
"dbpassword": "REMOVED SENSITIVE VALUE",
"installed": true
}
}

Client configuration

Browser:
Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:55.0) Gecko/20100101 Firefox/55.0

Operating system:
Ubuntu 16.04.3 LTS (GNU/Linux 4.4.0-93-generic x86_64)

Logs

Nextcloud log (data/owncloud.log)

Insert your Nextcloud log here

{"reqId":"WdIWtNeZC9@lWzos0mnQzQAAAA8","level":3,"time":"2017-10-02T10:36:36+00:00","remoteAddr":"147.156.52.141","user":"--","app":"PHP","method":"POST","url":"/nextcloud/index.php/apps/user_saml/saml/acs","message":"Function mcrypt_enc_get_iv_size() is deprecated at /var/www/html/nextcloud/apps/user_saml/3rdparty/vendor/onelogin/php-saml/extlib/xmlseclibs/xmlseclibs.php#320","userAgent":"Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:55.0) Gecko/20100101 Firefox/55.0","version":"12.0.3.3"}
{"reqId":"WdIWtNeZC9@lWzos0mnQzQAAAA8","level":3,"time":"2017-10-02T10:36:36+00:00","remoteAddr":"147.156.52.141","user":"--","app":"PHP","method":"POST","url":"/nextcloud/index.php/apps/user_saml/saml/acs","message":"Function mcrypt_generic_init() is deprecated at /var/www/html/nextcloud/apps/user_saml/3rdparty/vendor/onelogin/php-saml/extlib/xmlseclibs/xmlseclibs.php#325","userAgent":"Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:55.0) Gecko/20100101 Firefox/55.0","version":"12.0.3.3"}
{"reqId":"WdIWtNeZC9@lWzos0mnQzQAAAA8","level":3,"time":"2017-10-02T10:36:36+00:00","remoteAddr":"147.156.52.141","user":"--","app":"PHP","method":"POST","url":"/nextcloud/index.php/apps/user_saml/saml/acs","message":"Function mdecrypt_generic() is deprecated at /var/www/html/nextcloud/apps/user_saml/3rdparty/vendor/onelogin/php-saml/extlib/xmlseclibs/xmlseclibs.php#326","userAgent":"Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:55.0) Gecko/20100101 Firefox/55.0","version":"12.0.3.3"}
{"reqId":"WdIWtNeZC9@lWzos0mnQzQAAAA8","level":3,"time":"2017-10-02T10:36:36+00:00","remoteAddr":"147.156.52.141","user":"--","app":"PHP","method":"POST","url":"/nextcloud/index.php/apps/user_saml/saml/acs","message":"Function mcrypt_generic_deinit() is deprecated at /var/www/html/nextcloud/apps/user_saml/3rdparty/vendor/onelogin/php-saml/extlib/xmlseclibs/xmlseclibs.php#327","userAgent":"Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:55.0) Gecko/20100101 Firefox/55.0","version":"12.0.3.3"}
{"reqId":"WdIWtNeZC9@lWzos0mnQzQAAAA8","level":3,"time":"2017-10-02T10:36:36+00:00","remoteAddr":"147.156.52.141","user":"--","app":"PHP","method":"POST","url":"/nextcloud/index.php/apps/user_saml/saml/acs","message":"Function mcrypt_module_close() is deprecated at /var/www/html/nextcloud/apps/user_saml/3rdparty/vendor/onelogin/php-saml/extlib/xmlseclibs/xmlseclibs.php#328","userAgent":"Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:55.0) Gecko/20100101 Firefox/55.0","version":"12.0.3.3"}

Browser log

Insert your browser log here, this could for example include:

a) The javascript console log
b) The network log
c) ...

Reproduce the three listed SSO and logout steps on the reported Nextcloud 12.0.3.3 and inspect the user_saml SAML flow, starting with the referenced 3rdparty/vendor/onelogin/php-saml/extlib/xmlseclibs/xmlseclibs.php and the logged ACS requests. Done means an IDP-initiated logout correctly logs the user out of Nextcloud and the relationship between the mcrypt warnings and the failure is documented or resolved.