random.nextBytes(entropy);
Keypair pair2=Curve.createKeypair(entropy);
System.out.println("pair2: "+pair2);
Key session1=pair1.session(pair2.getPublic());
System.out.println("session1: "+session1);
Key session2=pair2.session(pair1.getPublic());
System.out.println("session1: "+session2);
}