The mailing list for users of the eduroam Configuration Assistant Tool (CAT)

[Matthew Slowe <Matthew.Slowe AT jisc.ac.uk>]

> On 6 Aug 2020, at 10:08, Alan Cox - UKRI <Alan.Cox AT ukri.org> wrote:
> 
> I've just experienced what seems to be the same error, though with a 
> Shibboleth 3.4.6 IdP - https://nerckwshibba.nerc.ac.uk/idp/shibboleth.

Our 3.4.6 IdP is also now seeing the same thing - as is the new v4 IdP.

Comparing the assertion for CAT with a "known good" assertion (against an SP 
which doesn't assert any algorithm requirements), I note these differences:

--- ref.xml     2020-08-06 10:38:45.000000000 +0100
+++ cat.xml     2020-08-06 10:38:56.000000000 +0100
@@ -4,8 +4,9 @@
     <xenc:EncryptionMethod xmlns:xenc="http://www.w3.org/2001/04/xmlenc#"; 
Algorithm="http://www.w3.org/2001/04/xmlenc#aes128-cbc"/>
     <ds:KeyInfo xmlns:ds="http://www.w3.org/2000/09/xmldsig#";>
       <xenc:EncryptedKey xmlns:xenc="http://www.w3.org/2001/04/xmlenc#"; 
Id="id" Recipient="sp-entityid">
-        <xenc:EncryptionMethod 
xmlns:xenc="http://www.w3.org/2001/04/xmlenc#"; 
Algorithm="http://www.w3.org/2001/04/xmlenc#rsa-oaep-mgf1p";>
+        <xenc:EncryptionMethod 
xmlns:xenc="http://www.w3.org/2001/04/xmlenc#"; 
Algorithm="http://www.w3.org/2009/xmlenc11#rsa-oaep";>
           <ds:DigestMethod xmlns:ds="http://www.w3.org/2000/09/xmldsig#"; 
Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
+          <xenc11:MGF xmlns:xenc11="http://www.w3.org/2009/xmlenc11#"; 
Algorithm="http://www.w3.org/2009/xmlenc11#mgf1sha1"/>
         </xenc:EncryptionMethod>
       </xenc:EncryptedKey>
     </ds:KeyInfo>


I don't know a huge amount about the inner workings of the different 
algorithms, but I do wonder if SimpleSAMLphp doesn't support "rsa-oaep" but 
does support "rsa-oaep-mgf1p" but, because the first one is listed first it's 
using that? 

-- 
Matthew Slowe
Technical Specialist - Trust & Identity, Jisc

Direct: 07442 097185
Team: 0300 300 2212, option 2
Lumen House, Library Avenue, Harwell Oxford, Didcot, OX11 0SG