SAML authentication: NullPointerException at JCEMapper.getJCEKeyAlgorithmFromURI

Problem

Using external authentication method with SAML protocol fails when returning back to Ubisecure SSO IDP with the following error message in Tomcat logs.

java.lang.NullPointerException

        at com.ubisecure.externals.apache.xml.security.algorithms.JCEMapper.getJCEKeyAlgorithmFromURI(JCEMapper.java:127)

Solution

This error is usually caused by the algorithm used to encrypt the authentication response not being supported by SSO. The external authenticator service must be configured to send the response using one of the supported algorithms.