--- old/src/jdk.crypto.ec/share/classes/sun/security/ec/XDHKeyAgreement.java	2018-08-30 11:09:24.985608001 -0400
+++ new/src/jdk.crypto.ec/share/classes/sun/security/ec/XDHKeyAgreement.java	2018-08-30 11:09:24.081608001 -0400
@@ -38,8 +38,11 @@
 import javax.crypto.KeyAgreementSpi;
 import javax.crypto.SecretKey;
 import javax.crypto.ShortBufferException;
+import javax.crypto.spec.SecretKeySpec;
 import java.util.function.Function;
 
+import sun.security.util.XECParameters;
+
 public class XDHKeyAgreement extends KeyAgreementSpi {
 
     private byte[] privateKey;
@@ -202,7 +205,14 @@
             throws IllegalStateException, NoSuchAlgorithmException,
             InvalidKeyException {
 
-        throw new NoSuchAlgorithmException("Not supported");
+        if (algorithm == null) {
+            throw new NoSuchAlgorithmException("Algorithm must not be null");
+        }
+        if (!(algorithm.equals("TlsPremasterSecret"))) {
+            throw new NoSuchAlgorithmException
+                ("Only supported for algorithm TlsPremasterSecret");
+        }
+        return new SecretKeySpec(engineGenerateSecret(), "TlsPremasterSecret");
     }
 
     static class X25519 extends XDHKeyAgreement {