сб, 14 дек. 2024 г. в 19:15, Matt Borland via Boost
The review of Hash2 by Peter Dimov and Christian Mazakas begins today Saturday, December 7th through Sunday December 15th, 2024.
This is my review of the proposed Hash2 library. Before the review I want to state that I am affiliated with the C++ Alliance.
- What is your evaluation of the design?
I read the paper on which the library is based on years ago and was very fond of the design outlined in it. It's great to see it finally realised. The library has a few innovations with regards to the original paper and after reading all of the review I consider those innovations useful.
- What is your evaluation of the implementation?
I only glanced at the implementation.
- What is your evaluation of the documentation?
I think, the documentation should be much more explicit about the implications of the design choices it made. After reading other people's comments and reviews it is clear to me that many people have not considered that the implications of the requirements of the HashAlgorithm concept are deliberate and not a mistake. Also, it will probably be good to explicitly state that no vetting by crypto experts or certifications by relevant agencies was done for any of the hashers provided by the library.
- What is your evaluation of the potential usefulness of the library? Do you already use it in industry?
I think that the library achieves what it tried to achieve (see below). And I consider that very useful.
- Did you try to use the library? With which compiler(s)? Did you have any problems?
In order to review Hash2 I experimented with integrating it into Boost.JSON. Hashing is used in 2 places in Boost.JSON. One of the uses is boost:: and std::hash support for JSON containers. Rewriting the existing code with Hash2 was very straightforward, as it is extremely similar to the existing usage of ContainerHash. The benefit of using Hash2 is exactly the one outlined in the original paper: ease of switching hashing algorithms. The second use of hashing in Boost.JSON is hashing of object keys. Rewriting the existing hashing function to become a HashAlgorithm was very straightforward (although, this could be because our algorithm is so simple). After that I experimented with changing the hashing algorithm with several of the ones provided by Hash2. This was extremely easy: changing an include line and changing the hash object type. This ability to trivially change hashing algorithms is as far as I can tell the main objective of the library. That is the reason for the requirements of HashAlgorithm. While those requirements may exclude many of the algorithms provided by the existing libraries today, I hope that maintainers of those libraries will see the utility of these additional operations and will provide them.
- How much effort did you put into your evaluation? A glance? A quick reading? In-depth study?
With reading documentation, all reviews and comments, and trying the library out, I've spent around 5 hours.
- Are you knowledgeable about the problem domain?
I'm not an expert on either hashing or cryptography. I suggest we ACCEPT the library into Boost.