Why signature need in SAML request for ADFS?

Question

Following is the SAML request send to ADFS

<?xml version="1.0" encoding="UTF-8"?>
<samlp:AuthnRequest xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol" ID="_84e533b7-4310-41de-8ec7-0af7afeb7979" Version="2.0" IssueInstant="2015-12-02T09:44:30Z" ProtocolBinding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST" Destination="https://XXXX.YYYY.ZZZZ/adfs/ls/" AssertionConsumerServiceURL="http://PPP.QQQ.RRR/SPDemo/Consume.aspx">
   <saml:Issuer xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion">http://XXXX.YYYY.ZZZZ/adfs/services/trust</saml:Issuer>
</samlp:AuthnRequest>

After compressing and converting to Base64String it is redirected to ADFS. URL shown below with SAML request

https://XXXX.YYYY.ZZZZ/adfs/ls/?SAMLRequest=hZHNbsIwEIRfJfLdsfODAhZEouVQJKpGJO2hl8okS7Ga2KnXoTx%2bA0kluNCjrflmZ3bnKJu6FcvOHfQWvjtA561XC%2fIxjWESRbuExlHAaRxUQKdQJpTLfSL3sEtmyYx4b2BRGb0goc%2bJt0bsYK3RSe36Lx5MaBBSHhZ8JuJYRPydeJk1zpSmflC6UvpzQTqrhZGoUGjZAApXinz5vBG9o9gNIhRPRZHR7CUviLfqIyot3WXswbkWBWMaj%2fQn%2fAo5n9rQr6zqNX5tSlkzWe2R1ciIt0QEe%2bYejcauAZuDPaoSXrebwak3GtAjba2pgujWKc9W0Bg20r7E9kS8U1NrFJct3u%2fSjsVJOj%2brxWVZ9oq%2fj8u%2f8CQdo%2f7XGYd2yJzt0M3Z1dR0eN3ePf0F

But I am getting following error

Checking for detail error in Event Viewer I got

It seems that the server required the signed SAML request but I haven't mentioned anywhere that signed SAML request is required. Also SignedSamlRequestsRequired property is set to false

So, Why ADFS 2.0 is asking for signed SAML request ?

Is there anything that is needed to be done so that signed SAML request is not required or if required what will be the value of signature that will signed the SAML request?

Answer 1

I am able to solved it.

The problem was with wrong setting of issuer in SAML request.

After setting the appropriate issuer,ie http://PPP.QQQ.RRR/SPDemo , as shown in following SAML Request I am able to do SP-Initiated login without any ADFS error

<?xml version="1.0" encoding="UTF-8"?>
<samlp:AuthnRequest xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol" ID="_bd613bda-e506-4747-91c7-96a4d75c67fc" Version="2.0" IssueInstant="2015-12-03T05:51:52Z" ProtocolBinding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST" Destination="https://XXXX.YYYY.ZZZZ/adfs/ls/" AssertionConsumerServiceURL="https://PPP.QQQ.RRR/SPDemo//Consume.aspx">
   <saml:Issuer xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion">http://PPP.QQQ.RRR/SPDemo</saml:Issuer>
</samlp:AuthnRequest>

Previously used wrong issuer was http://XXXX.YYYY.ZZZZ/adfs/services/trust