RustCrypto / RustCrypto/crypto-bigint

Expose bounded-stack schoolbook Montgomery operations

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Dominant language
Rust
Stars
309
Forks
95
Avg merge
1d 14h
Merged PRs (30d)
3

Description

mul::schoolbook, montgomery_multiply_inner, and friends exist but are pub(crate), so the only public 4096-bit multiply goes through karatsuba::wrapping_mul_fixed, whose fixed-size temporaries produce a ~25 KiB stack frame — unusable on 16 KiB-stack firmware (no_std, no-alloc env).

Request: public wrapping_mul_schoolbook-style entry points (or a precision-bounded vartime pow).

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Research direction

Start by reading the existing mul::schoolbook, montgomery_multiply_inner, and karatsuba::wrapping_mul_fixed entry points. Compare their stack requirements for 4096-bit multiplication in the no_std context. Done when a public schoolbook-style operation or precision-bounded vartime pow path avoids the roughly 25 KiB stack frame.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
cryptography, embedded-iot
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Active
Clarity
Mostly clear
Newbie friendliness
55/100

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