how to force idp v3 to sign saml assertion

[Jehan Procaccia]

hello,

we have a software developer that tries to enable shbboleth SSO with our 
federation based on shibboleth IDPs

Although everything works fine with our shibd or simplesamlphp SPs. This 
one uses https://github.com/lightSAML/lightSAML

the problem is that the lightSaml SP complains that the IDP doesn't sign 
SAML assertions, it misses element <ds:Signature> within the decrypted 
assertion .

indeeed , lightsaml needs signed SAML assetions according to 
https://github.com/lightSAML/lightSAML/issues/27

could it be a feature or parameter in my IDP (v 3.2.1) that isn't set 
correctly in order to force singing SAML assertions ?

Thanks for your help .