RustCrypto / RustCrypto/crypto-bigint
A tighter bound on `sqrt()` iterations
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- Dominant language
- Rust
- Stars
- 309
- Forks
- 95
- Avg merge
- 1d 14h
- Merged PRs (30d)
- 3
Description
Currently, as prescribed by Hast, "Note on computation of integer square roots" (https://github.com/RustCrypto/crypto-bigint/files/12600669/ct_sqrt.pdf), we are performing floor(log2(BITS)) + 2 iterations in Uint::sqrt() (to get x_n and x_{n+1}, where n = floor(log2(BITS)) + 1). But the tests indicate that it may be enough to only do floor(log2(BITS)) iterations. Need to check.
cc @HastD
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First steps
- Read the whole issue, then the project's contributing guide.
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- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reading the linked Hast note and inspecting Uint::sqrt() together with the existing tests that cover its iteration count. Establish whether floor(log2(BITS)) iterations are sufficient, then update the bound and tests only if the result is proven across the supported sizes.
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Assessment
- Tech stack
- rust
- Domain
- cryptography
- Issue type
- Refactor
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 42/100