Files
LithosAnanake/kernel/include/starkernel/scalar25519.h
T
rajamesandJunie a8b70e88d3 Reorganize source tree: kernel/, v3/, v4/ split and board infrastructure
Source tree reorganization:
- Move StarForth v3 engine to v3/ (src/, include/, Makefile)
- Move kernel to kernel/ (src/, include/, linker/, Makefile)
- Create v4/ skeleton for F18-ISA golden model (DECOMPOSITION.md, JUSTIFICATION.md)
- Move FABRIC-0..4.md to docs/fabric/
- Move ONTOLOGY.md and ROADMAP.md to docs/

Board infrastructure:
- Add boards/ser5/, boards/raspi/, boards/milkv/, boards/zynq7020/
- Each board has board.mk (ISA, CPU flags, boot recipe) and README.md
- Root Makefile becomes thin dispatcher: boot_image, all, clean, docs take TARGET
- make boot_image TARGET=SER5|RASPI|MILKV builds one GPT/MBR image per board
- ZYNQ7020 target exists but stops with clear error (ARMv7 port not built yet)
- scripts/mkdiskimage.sh builds disk images for all boards

Docs pipeline:
- docs/book/ with LaTeX master (main.tex) and Makefile
- pandoc converts Markdown to LaTeX at build time
- Two Lua filters: table-widths.lua (wide tables wrap), code-breaks.lua (inline code breaks)
- make docs builds single PDF (754 pages, 0 missing characters)
- make docs TARGET=<board> adds board appendix
- build/docs/<book|board>/meta.tex stamps git commit into PDF

Bug fixes:
- 42 include paths that only worked by accident now use correct relative paths
- clang-18 hardcode replaced with configurable CC variable (fixed aarch64 build)
- Pi 5: kernel_2712.img linked at 0x80000, .bss zeroed, memory reserved
- Doxyfile, .clang-tidy, README.md, Kconfig paths updated

Verified:
- Hosted v3 build passes 1012 tests, 0 failures
- SER5 image boots in QEMU (OVMF), POST passes, K exact (65536 = Q48_ONE)
- Milk-V image boots in QEMU (OpenSBI + U-Boot + bootefi), POST passes
- make clean TARGET=<board> removes only that board and its ISA objects
- make all builds all boards, hosted v3, and docs in one run

Co-authored-by: Junie <junie@jetbrains.com>
2026-10-01 15:40:09 -04:00

38 lines
1.7 KiB
C

/* scalar25519.h -- arithmetic mod L (the Ed25519 base point's order),
* for reducing SHA-512 output to a valid scalar and checking a
* signature's S component for the RFC 8032 malleability requirement
* (S < L, not just S < 2^256).
*
* Deliberately NOT the intricate hand-tuned "sc_reduce" reduction most
* reference implementations use (a bespoke Barrett-style reduction with
* constants specific to L, notoriously easy to transcribe wrong) --
* this is a plain binary long-division reduction, one bit at a time.
* O(512) steps per reduction; this is a verify-only, non-hot-path
* library (one reduction per signature check), so the simpler,
* more obviously-correct approach is the right tradeoff here.
*/
#ifndef SCALAR25519_H
#define SCALAR25519_H
#include <stdint.h>
/* 32-byte little-endian scalars, reduced mod L where noted. */
/* Reduce a 64-byte little-endian value (e.g. raw SHA-512 output) mod L,
* producing a 32-byte little-endian result < L. */
void scalar_reduce512(uint8_t out[32], const uint8_t in[64]);
/* 1 if the 32-byte little-endian scalar is < L (a well-formed,
* non-malleable signature component per RFC 8032), else 0. */
int scalar_lt_L(const uint8_t s[32]);
/* out = (a*b + c) mod L, all 32-byte little-endian scalars (a, b, c need
* not already be reduced mod L, though every caller in this codebase
* passes already-reduced inputs). Needed for EdDSA signing's
* S = (k*a + r) mod L step -- verify never needed scalar multiplication,
* only reduction, so this didn't exist until signing did. */
void scalar_muladd(uint8_t out[32], const uint8_t a[32], const uint8_t b[32],
const uint8_t c[32]);
#endif /* SCALAR25519_H */