Two points:
- The point of using a binary search is specifically to avoid doing an end-to-end search of the entire tree. However, it's only of value if the data in the subordinate hashes are collectively in sorted order. I'm betting they're not.
- Off the top of my head, I can't think of a way to shorten the search if those sub-hashes aren't in sorted order. I think you're in for a hash-tree variant of an old-fashioned sequential search.
Which, unfortunately, has you back where you started.
- Steve