RustCrypto / RustCrypto/universal-hashes
Add backend for 32 bit targets with wide multiplication?
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- Dominant language
- Rust
- Stars
- 39
- Forks
- 23
- Avg merge
- 1h 57m
- Merged PRs (30d)
- 2
Description
Currently polyval (and thus crates built on top of it) uses 32-bit soft backend which was written with targets without wide multiplication in mind. However, this code can be quite inefficient for targets which do support wide multiplication, such as:
- WASM32:
u32s can be extended to 64 bits and multiplied usingi64.mul. - RISC-V: wide multiplication is implemented by combining
MULHUandMULoperations (hardware may fuse them later into a single instruction).
Also it may be worth to add a soft backend for 64-bit targets without wide multiplication? Though right now I can't name a target for which it could be useful.
Contributor guide
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First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by inspecting the existing 32-bit soft backend used by polyval, then compare how WASM32 and RISC-V expose wide multiplication. Determine the backend boundary and target conditions needed for the proposed implementation, and verify that the resulting backend preserves polyval behavior while improving support for targets with wide multiplication.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust, wasm
- Domain
- cryptography
- Issue type
- Feature
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100