I did a bunch of protocol level design in the 90's and one of the handful of things that taught me was _ALWAYS_ use at least a CRC with a standard polynomial. Its just not worth it, in the 2000's I relearned the lesson when it comes to data at rest (on disk/etc). If nothing else both of those will catch "bugs" rather than silently corrupting things and leading to mysteries long after the initial data was corrupted.

I just had this discussion (about why TCP's checksum was a huge mistake) a couple days ago. That link is going to be useful next time it comes up.