I think it does stack if the perplexity filter is applied before the compression step, which relies on an underlying assumption that it's easier to secure the internet connection choke point rather than the entire data center.
I will try to continue the discussion here for simplicity.
The perplexity filter works best if the attacker doesn't have complete control of the entire data center, but instead limited access to some machines. An underlying assumption is that it's easier to secure the internet connection choke point, rather than everything going on inside the data center.
This can be stacked with compression by applying the perplexity filter before the compression step.
Assuming that the attacker has access to the perplexity filter model, it would still reduce the possible information density if they have to perform some sort of arithmetic encoding scheme that has low perplexity. I had coworkers working on exactly this problem of encoding information into natural language using arithmetic encoding and GPT-2 small, and there's a major trade-off between the perplexity of the language generated and the density of the encoded information, although I don't have numbers available to quantify this trade-off.
Another potential option (that could stack with text compression) is to filter outgoing data. In particular, if we only allow outgoing data to be language tokens, and we filter the outgoing data to have low perplexity as measured by a small, secret language model, then it could become very difficult to encode terabytes of model weights in a way that has low perplexity.
I discuss this idea more here.
Thanks for this comment, by the way! I added a paragraph to the beginning to make this post more clear.
The purpose of this proposal is to limit anyone from transferring model weights out of a data center. If someone wants to steal the weights and give them to China or another adversary, the model weights have to leave physically (hard drive out of the front door) or through the internet connection. If the facility has good physical security, then the weights have to leave through the internet connection.
If we also take steps to secure the internet connection, such as treating all outgoing data as language tokens and using a perplexity filter, then the model weights can be reasonably secure.
We don't even have to filter all outgoing data. If there was 1 Gigabyte of unfiltered bandwidth per day, it would take 2,000 days to transfer GPT-4's 2 terabytes of weights out (although this could be reduced by compression schemes).
I would guess that it would learn an exact algorithm rather than heuristics. The challenging part for OthelloGPT is that the naive algorithm to calculate board state from input tokens requires up to 60 sequential steps, and it only has 8 layers to calculate the board state and convert this to a probability distribution over legal moves.
I think it's pretty plausible that this is true, and that OthelloGPT is already doing something that's somewhat close to optimal within the constraints of its architecture. I have also spent time thinking about the optimal algorithm for next move prediction within the constraints of the OthelloGPT architecture, and "a bag of heuristics that promote / suppress information with attention to aggregate information across moves" seems like a very reasonable approach.
In Othello, pieces must be played next to existing pieces, and the game is initialized with 4 pieces in the center. Thus, it's impossible for the top left corner to be played within the first 5 moves, and extremely unlikely in the early portion of a randomly generated game.
I had the following results:
Stockfish level 2 vs Stockfish level 0, 0.01 seconds per move, 5k games:
0 random moves: win rate 81.2%
20 random moves: win rate 81.2%
40 random moves: 77.9%
95% confidence interval is about +- 1%
Stockfish level 15 vs level 9, 0.01 seconds per move, 5k games:
0 random moves: 65.5%
20 random moves: 72.8%
40 random moves: 67.5%
Once again, 95% confidence interval is about +- 1%
At 120 seconds per move, both of these level differences correspond to ~300 Elo: https://github.com/official-stockfish/Stockfish/commit/a08b8d4
This is 0.01 seconds per move. It appears that less search time lowers the Elo difference for level 15 vs level 9. A 65% win rate corresponds to a ~100 Elo difference, while a 81% win rate corresponds to a 250-300 Elo difference.
Honestly not too sure what to make of the results. One possible variable is that in every case, the higher level player is White. Starting in a game with a random position may favor the first to move. Level 2 vs level 0 seems most applicable to the Chess-GPT setting.
I agree. In particular, there's a huge advantage to the defender due to the scale of the model weights. All the defense has to do is raise the bar high enough that an adversary can't exfiltrate model weights during the lifetime of the model.
If the adversary gains access to the weak model, it still reduces the possible encoded information density, as I discuss here. I haven't done the experiments, but I would guess this reduction improves significantly if the adversary doesn't have access to the weak model.
Various ways of changing the weak model weights or retraining the weak model with new data could also increase the size of the defender's advantage.