Working on designs for better chunking. Having a hard time finding a way to totally obscure file sizes, but otherwise a good design seems to be coming together. I particularly like that the new design puts the chunk count in the Key (which is then encrypted for special remotes, rather than having it be some special extension.

While thinking through chunking, I realized that the current chunking method can fail if two repositories have different chunksize settings for the same special remote and both upload the same key at the same time. Arn't races fun? The new design will eliminate this problem; in the meantime updated the docs to recommend never changing a remote's chunksize setting.