B777 First Officer reported encountering wake turbulence at FL330 from an A380 on descent into EDFF/FRA.

Narrative

The wake turbulence event began just after starting descent from FL350 between approximately FL344-FL325; lasted about 100 seconds and included 8 uncommanded rolling motions right and left that which took nearly 3/4 yoke deflection to counter. The maximum bank angle was about 7-10 degrees left and right with significant yaw motions noticed opposite to the roll. Also present was light-moderate-severe turbulence during the entire event. We experienced (1.7G-0.7G). No high/low speed limitations or excursions were felt or noticed. The engines performed flawlessly. We kept them out of idle; per the Captain's orders to prevent them from flaming out or compressor stalling. I was the flying pilot who noticed the wheel deflection first. I immediately brought this to the attention of the Captain. I then grabbed the control wheel and disengaged the autopilot. I was surprised how much deflection; and force it took to overcome the roll in an attempt to stay level. The Captain then joined me on the controls. After the first 2 rolling moments; it seemed to be dissipating; so I reengaged the autopilot only to have the event continue for 6 more cycles; but to a lesser degree. We both helped the autopilot stay engaged by adding input in the proper direction to keep the wings as level as possible. The speed was stable at approximately 286 knots during the entire event. After the event we slowed the aircraft to 250 knots and maintained that all the way to the airport in case we were having a flight control malfunction or some other airframe damage. We checked the positions several times on the MFD during the descent to verify flight control positions; all were showing normal and symmetrical. I disengaged the autopilot on downwind at 250 knots to verify the aircraft flight controls were functioning properly and that the aircraft flew normally. Everything seemed totally normal. I made a faster than normal approach to 25L; at the recommendation of the Captain. We asked for and received landing clearance to land on 25C. The landing was normal and we wrote up the event in the log book as having experienced a severe turbulence event. I now believe it was a severe wake turbulence event from an A380 or B747 which must have traveled through the SPI area minutes before we got there. Cause: There must have flown through the wake of either a SUPER A380 or B747 that passed through the SPI area either climbing out of FRA; or MUC or one passing by opposite direction. We were not following anyone into FRA. The Controllers never said anything and we never asked if there was anyone there before us with a super callsign since the language is always problematic. We hope to never experience the wake of a larger; heavier aircraft again as we felt barely able to keep our B777 from becoming uncontrollable.