when(dc.toString()).thenReturn("LARGEDC");

            NtlmChallenge nc = new NtlmChallenge(challenge, dc);
            String result = nc.toString();

            // Should contain hex representation of 0-15
            assertTrue(result.contains("0x"));
            assertTrue(result.contains("dc=LARGEDC"));
            // The hex string should be 32 chars long (16 bytes * 2)