diff --git a/lib/constants.js b/lib/constants.js
index <HASH>..<HASH> 100644
--- a/lib/constants.js
+++ b/lib/constants.js
@@ -21,6 +21,8 @@ module.exports = {
     authentication: 'authentication',
     capabilityDelegation: 'capabilityDelegation',
     capabilityInvocation: 'capabilityInvocation',
-    assertionMethod: 'assertionMethod'
+    assertionMethod: 'assertionMethod',
+    keyAgreement: 'keyAgreement',
+    contractAgreement: 'contractAgreement'
   }
 };
Add more proof purposes to constants.