Problem creating LTI Tool Consumer

Blog Post created by bwalker99 on Aug 25, 2016

In the past, I've successfully created java LTI Tool Providers (using Blackboard's BLTI-Sandwich) which have been working nicely for a few years.  The TPs are an integral part of our BB courses, and are called from many places.

Now I'm trying to create a java-based LTI Tool Consumer with the same library, but the signature process doesn't seem to be working.


BLTIMessage msg = new BLTIMessage( "ConsumerKey" );

// fill in parameters...

BLTIConsumer consumer = new BLTIConsumer( "POST", launchsite,msg );


List<Map.Entry<String, String>> launchParams = consumer.getParameters();

// then autopost a form with the parameters embedded.


The error on the TP webserver is: 

net.oauth.OAuthProblemException: signature_invalid

        at net.oauth.signature.OAuthSignatureMethod.validate(

        at net.oauth.SimpleOAuthValidator.validateSignature(

        at net.oauth.SimpleOAuthValidator.validateMessage( 


(I've double checked everything, and can connect to the TP from other TCs, including Blackboard).

Any ideas?

Thanks, bob