Add support for AES-GCM #179

Skywalker-11 · 2019-09-24T16:16:52Z

simplsamlphp currently does not support AES in GCM mode.

If an IDP uses AES-GCM for encryption of the ssertions eg:

<saml2:EncryptedAssertion xmlns:saml2="urn:oasis:names:tc:SAML:2.0:assertion">
  ....
  <xenc:EncryptionMethod Algorithm="http://www.w3.org/2009/xmlenc11#aes128-gcm" xmlns:xenc="http://www.w3.org/2001/04/xmlenc#"/> 
   ....

this creates an error in form of the following message on a SP running simplesamlphp:

simplesamlphp: 3  Decryption failed: Could not locate key algorithm in encrypted data.
simplesamlphp: 3  SimpleSAML\Error\Error: UNHANDLEDEXCEPTION
simplesamlphp: 3  Backtrace:
simplesamlphp: 3  1 /opt/simplesamlphp/www/_include.php:17 (SimpleSAML_exception_handler)
simplesamlphp: 3  0  (N/A)
simplesamlphp: 3  Caused by: Exception: Failed to decrypt XML element.
simplesamlphp: 3  Backtrace:
simplesamlphp: 3  7 /opt/simplesamlphp/vendor/simplesamlphp/saml2/src/SAML2/Utils.php:575 (SAML2\Utils::decryptElement)
simplesamlphp: 3  6 /opt/simplesamlphp/vendor/simplesamlphp/saml2/src/SAML2/EncryptedAssertion.php:98 (SAML2\EncryptedAssertion::getAssertion)
simplesamlphp: 3  5 /opt/simplesamlphp/modules/saml/lib/Message.php:391 (SimpleSAML\Module\saml\Message::decryptAssertion)
simplesamlphp: 3  4 /opt/simplesamlphp/modules/saml/lib/Message.php:647 (SimpleSAML\Module\saml\Message::processAssertion)
simplesamlphp: 3  3 /opt/simplesamlphp/modules/saml/lib/Message.php:614 (SimpleSAML\Module\saml\Message::processResponse)
simplesamlphp: 3  2 /opt/simplesamlphp/modules/saml/www/sp/saml2-acs.php:134 (require)
simplesamlphp: 3  1 /opt/simplesamlphp/lib/SimpleSAML/Module.php:236 (SimpleSAML\Module::process)
simplesamlphp: 3  0 /opt/simplesamlphp/www/module.php:9 (N/A)

Depending on change in library xmlseclibs (robrichards/xmlseclibs#134)

The text was updated successfully, but these errors were encountered:

blai-cartera · 2020-03-16T19:38:25Z

@Skywalker-11 have you found any alternatives to simplesamlphp or a way to include 3rd party support of aes-gcm for simplesamlphp users?

Skywalker-11 · 2020-03-16T20:03:43Z

I am not using simplesaml myself but noticed the error when interacting with 3rd party SPs

melanger · 2020-05-27T09:35:35Z

AES-GCM is the default in Shibboleth 4.0, so missing support breaks compatibility of SimpleSAMLphp with a growing number of IdPs.

tvdijen · 2020-05-27T09:54:53Z

@melanger The issue here is not SimpleSAMLphp, but two dependency-levels down in the xmlseclibs library.. So, unless you can open up a can of crypto-savvy PHP developers, this is really out of our control.

melanger · 2020-05-27T10:19:43Z

@tvdijen There is an open issue in the library as well, robrichards/xmlseclibs#134, but it seems that the support was actually added in 3.1 https://github.com/robrichards/xmlseclibs/releases/tag/3.1.0

melanger · 2020-05-27T10:21:25Z

Requires PHP 7.1+, but SimpleSAML already requires 7.2+ on master

jaimeperez · 2020-05-27T10:24:15Z

I might be mistaken here, but I would say this is just a matter of updating the xmlseclibs dependency, since 3.1.0 implements support for AES-GCM.

IlariExove · 2020-07-31T15:09:20Z

I see Shibboleth 4.0 IdPs using http://www.w3.org/2009/xmlenc11#aes128-gcm algorithm for encryption. This is a rising concern as 4.0 went GA in March. IdPs are rolling out v4 to production soon.

tvdijen · 2020-07-31T15:41:21Z

If you're using SimpleSAMLphp:

On 1.18 you can get this working by running composer require robrichards/xmlseclibs:^3.1.
1.19 will officially include this.

If you're using this library directly:

Use v4.1.8 of the libary

s0rin · 2020-09-01T10:32:54Z

The workaround in SSP 1.18.7 to install manually xmlseclibs 3.1.0 over the existent 3.0.8 didn't work for me, the error "Failed to decrypt XML element" still occur. How to check the xmlseclibs installed version?

tvdijen · 2020-09-01T15:49:17Z

You can check the installed version in the composer.lock file
Also, what's your PHP-version? xmlseclibs will not process aes-128-gcm on PHP <7.1

s0rin · 2020-09-03T07:47:38Z

The PHP version is right:

# php -v
PHP 7.2.33 (cli) (built: Sep  1 2020 05:35:29) ( NTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.2.0, Copyright (c) 1998-2018 Zend Technologies
    with Zend OPcache v7.2.33, Copyright (c) 1999-2018, by Zend Technologies

but the xmlseclibs is not:

# cat /var/simplesamlphp/composer.lock | grep xmlseclibs
                "robrichards/xmlseclibs": "^3.0.4",

Note. With the newer SSP 1.18.8 is no change :-(

In conclusion the workaround for 1.18.x to install xmlseclibs with composer manually is not working (maybe some steps are missing, i.e. to edit composer.lock?). I will rather wait for 1.19...

tvdijen · 2020-09-03T08:01:24Z

1.18.8 has the right one;
https://github.com/simplesamlphp/simplesamlphp/blob/simplesamlphp-1.18/composer.lock#L419

So it must be something else...

s0rin · 2020-09-03T08:26:45Z

and here? https://github.com/simplesamlphp/simplesamlphp/blob/simplesamlphp-1.18/composer.lock#L509

tvdijen · 2020-09-03T08:52:56Z

That one's not relevant.. The one I tagged is the one actually installed & packaged...
I'll see if I can run a few tests with aes-gcm encrypted assertions this weekend. and see if I can figure this out..
Reopening this so I won't forget

s0rin · 2020-09-04T07:48:45Z

I've retested 1.18.8 today and AES-GCM is still not working :-(

tvdijen · 2020-09-04T09:34:41Z

That doesn't surprise me, because nothing has changed in SimpleSAMLphp or the saml2 library..
I just need to find the time to work out a test-setup with AES-GCM encrypted assertions so I can reproduce your issue and see what changes we may need to get this working..

tvdijen · 2020-09-05T11:45:02Z

OK, I got it working now.. I got off on the wrong foot last night a bit..

You need: robrichards/xmlseclibs#213 and 1f0c32f
And then in SimpleSAMLphp set https://github.com/simplesamlphp/simplesamlphp/blob/e4246a2a0286e553f7544e20f0fd246aeea3d5df/modules/saml/lib/Message.php#L312 to the right algo and you're all set!

I don't think it makes much sense to tag a new saml2-release until xmlseclibs is fixed, so I'm keeping this open and in the meanwhile I can try and work on making the algorithm configurable in SSP. I've also asked Rob for a bugfix release on xmlsec and that's about as much as I can for you do right now

s0rin · 2020-09-14T12:07:35Z

Retesting with 1.19-rc1 but still not working.

SimpleSAML\Error\Error: UNHANDLEDEXCEPTION

Backtrace:
1 www/_include.php:17 (SimpleSAML_exception_handler)
0 [builtin] (N/A)
Caused by: Exception: Failed to decrypt XML element.
Backtrace:
7 vendor/simplesamlphp/saml2/src/SAML2/Utils.php:537 (SAML2\Utils::decryptElement)
6 vendor/simplesamlphp/saml2/src/SAML2/EncryptedAssertion.php:119 (SAML2\EncryptedAssertion::getAssertion)
5 modules/saml/lib/Message.php:413 (SimpleSAML\Module\saml\Message::decryptAssertion)
4 modules/saml/lib/Message.php:674 (SimpleSAML\Module\saml\Message::processAssertion)
3 modules/saml/lib/Message.php:642 (SimpleSAML\Module\saml\Message::processResponse)
2 modules/saml/www/sp/saml2-acs.php:145 (require)
1 lib/SimpleSAML/Module.php:266 (SimpleSAML\Module::process)
0 www/module.php:10 (N/A)

tvdijen · 2020-09-14T13:46:57Z

Maybe because 1.19-rc1 is ten days old and I got it working only 9 days ago?
For it to work, you still need the manual changes as I described..

back-2-95 · 2020-10-01T08:18:49Z

Seems that robrichards/xmlseclibs 3.1.1 includes the needed change:
robrichards/xmlseclibs@3.1.0...3.1.1

And when updating with Composer:
composer update --with-dependencies simplesamlphp/simplesamlphp
it updates robrichards/xmlseclibs to 3.1.1

SimpleSAMLphp also seems to have this change https://github.com/simplesamlphp/simplesamlphp/blob/e4246a2a0286e553f7544e20f0fd246aeea3d5df/modules/saml/lib/Message.php#L312 in https://github.com/simplesamlphp/simplesamlphp/blob/v1.18.8/modules/saml/lib/Message.php#L310.

tvdijen · 2020-10-01T08:33:37Z

There's one PR for that which will land in 1.19; simplesamlphp/simplesamlphp#1377

back-2-95 · 2020-10-01T09:04:36Z

I just got word from my university contact handling the Shibboleth 4:

Changing encryption from GCM (default in Shibboleth 4) to CBC made it work with both:

SSP 1.18.6 (we had this before Shibboleth was updated)
SSP 1.18.8 (works also with GCM)

JanOppolzer · 2020-11-26T19:46:31Z

I can confirm that SimpleSAMLphp 1.18.8 with updated xmlseclibs to 3.1.1 and updates to EncryptedAssertion.php and Message.php according to #179 (comment) makes it working with an Shibboleth IdP 4.0.1 using AES-GCM encryption.

Looking forward to see AES-GCM support in 1.19 out of the box.

tvdijen · 2020-11-26T19:54:03Z

Thanks @JanOppolzer ! There's some discussion on the changes to SSP 1.19, but the next RC should ease all of your problems.

This is required to support AES-GCM. See also simplesamlphp/saml2#179 (comment)

Shib4 IdP now uses AES-GCM keys by default, adding two patches following simplesamlphp/saml2#179 (comment) With 1.19 this should no longer be necessary.

tvdijen closed this as completed Jul 31, 2020

tvdijen reopened this Sep 3, 2020

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This was referenced Sep 5, 2020

Configurable symmetric key algorithm simplesamlphp/simplesamlphp#1376

Closed

Configurable symmetric encryption algorithm simplesamlphp/simplesamlphp#1377

Merged

tvdijen closed this as completed in simplesamlphp/simplesamlphp#1377 Dec 15, 2020

NicolasLiampotis added a commit to rciam/simplesamlphp that referenced this issue Jan 11, 2021

Bump robrichards/xmlseclibs dependency to 3.1.1

461b13f

This is required to support AES-GCM. See also simplesamlphp/saml2#179 (comment)

msalle added a commit to rcauth-eu/aarc-ansible-wayf that referenced this issue Jan 18, 2021

Add two patches for Shib4 IdP support

e26b642

Shib4 IdP now uses AES-GCM keys by default, adding two patches following simplesamlphp/saml2#179 (comment) With 1.19 this should no longer be necessary.

lselanne mentioned this issue Jul 2, 2021

GCMEncryption catalyst/moodle-auth_saml2#582

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Add support for AES-GCM #179

Add support for AES-GCM #179

Skywalker-11 commented Sep 24, 2019 •

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Add support for AES-GCM #179

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