The ideas behind SIV are pretty straightforward, and I don't suspect many in the field think it's not an obvious idea. The hard work is in finding a way to bui

The ideas behind SIV are pretty straightforward, and I don't suspect many in the field think it's not an obvious idea. The hard work is in finding a way to build a mode that minimizes the downsides as much as possible (so it can be used widely) and in proving that the construct doesn't violate any expectations or guarantees of the mode it's replacing. A lot of cryptography required a stroke of brilliance to come up with an idea and see it through. AES-GCM-SIV just required putting in the hard, tedious work (this is very much not meant to undersell the effort involved, just to emphasize that the hard part here was labor, not ideas).