java - The best way to encrypt a SAML assertion in Java without using the OpenSAML library

Question

I have a SAML assertion in an XML file. What I need to do is to encrypt it to match the EncryptedAssertion specification of the SAML2.0.

Now I cannot use the OpenSAML library which would make the life easier. I will need to write something myself from the scratch.

I am not getting any tutorial on how to encrypt an XML (e.g. the SAML assertion) file in Java that will follow the xmlenc specification.

Any help will be highly appreciated.

Thanks in advance.

Ripul