Derive seed for MurmurHash64A automatically#6
Merged
Merged
Conversation
Given the hash of the empty string for the root directory entry we can deterministically derive the seed used for MurmurHash64A. Mathematically, this is possible due to how all three steps (xor, mul, xor) of hashing an empty string with this algorithm are invertible. As we don't know what algorithm could be used in the future the code has a safeguard in that it validates the computed seed against the hash of the next non-empty directory path rep.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Given the hash of the empty string for the root directory entry we can deterministically derive the seed used for MurmurHash64A.
Mathematically, this is possible due to how all three steps (xor, mul, xor) of hashing an empty string with this algorithm are invertible.
As we don't know what algorithm could be used in the future the code has a safeguard in that it validates the computed seed against the hash of the next non-empty directory path rep.