What is sm3 CLAUDE.md?

A set of project instructions for building SM3, a cryptographic hash function, as a Swift package. It describes the required Swift version, implementation limits, and official algorithm details.

Use it when developing or reviewing an all-Swift SM3 implementation, including its 256-bit hash output and standard-defined constants.

It gives the coding agent the rules needed to keep the implementation compatible with the SM3 standard and the project's technical requirements.

How ekscrypto/sm3 configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to ekscrypto/sm3. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/ekscrypto/sm3/main/CLAUDE.md

Clone the repo

git clone --depth 1 https://github.com/ekscrypto/sm3

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

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Your own site

<a href="https://agentmods.dev/instructions/ekscrypto/sm3/claude-md"><img src="https://agentmods.dev/badge/instructions/ekscrypto/sm3/claude-md/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

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Per session 3,860 This file is loaded in full into every session.

When invoked 3,860 The same file — it is already loaded in full.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.03860	$0.03860
Opus 5.5	$0.01544	$0.01544
Sonnet 5.5	$0.00772	$0.00772
Haiku 4.5	$0.00386	$0.00386

Measured 2mo ago against content hash 7f8c30a899fe, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

sm3 CLAUDE.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

CLAUDE.md · 436 lines

How it starts

The opening of the file, as written. The whole thing — 436 lines — stays where its author put it; the contents beside it link to each section on GitHub.

SM3 Swift Implementation Project

Project Description

This project implements the ShangMi 3 (SM3) cryptographic hash algorithm as a Swift Package. The implementation must:

Use Swift 6.2
Be entirely implemented in Swift (no C or Objective-C)
No third-party libraries
Produce 256-bit hash values
Be compatible with official SM3 specifications

SM3 Algorithm Overview

SM3 is a cryptographic hash function published by the Chinese National Cryptography Administration on 2010-12-17 as GM/T 0004-2012: SM3 cryptographic hash algorithm. It is also standardized in:

GB/T 32905-2016 (Chinese standard)
ISO/IEC 10118-3:2018 (International standard)
IETF Draft: draft-sca-cfrg-sm3

Key Characteristics

Output Size: 256 bits (32 bytes)
Block Size: 512 bits (64 bytes)
Input Limit: Messages up to 2^64 bits
Construction: Merkle-Damgård with Davies-Meyer compression function
Security Level: Similar to SHA-256

Technical Specification

Constants

Initial Hash Value (IV)

0x7380166f, 0x4914b2b9, 0x172442d7, 0xda8a0600,
0xa96f30bc, 0x163138aa, 0xe38dee4d, 0xb0fb0e4e

Step Constants (T_j)

For j = 0 to 15: 0x79cc4519
For j = 16 to 63: 0x7a879d8a

Boolean Functions

FF_j (Message Schedule Function)

For j = 0 to 15: FF_j(X,Y,Z) = X ⊕ Y ⊕ Z
For j = 16 to 63: FF_j(X,Y,Z) = (X ∧ Y) ∨ (X ∧ Z) ∨ (Y ∧ Z)

GG_j (Compression Function)

For j = 0 to 15: GG_j(X,Y,Z) = X ⊕ Y ⊕ Z
For j = 16 to 63: GG_j(X,Y,Z) = (X ∧ Y) ∨ (¬X ∧ Z)

Permutation Functions

P₀(X)

P₀(X) = X ⊕ (X <<< 9) ⊕ (X <<< 17)

Where <<< denotes circular left shift (rotate left).

P₁(X)

P₁(X) = X ⊕ (X <<< 15) ⊕ (X <<< 23)

Algorithm Steps

1. Message Padding

Given a message M of length l bits:

Append a single "1" bit to the message
Append k "0" bits where k is the smallest non-negative solution to:
```
l + 1 + k ≡ 448 (mod 512)
```
Append the 64-bit big-endian representation of l
Result: padded message with length ≡ 0 (mod 512)

Read the full file on GitHub · 436 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

2mo ago First seen · 436 lines · 3,860 tokens per session scan A 7f8c30a899fe

Subscribe to this mod's changes

sm3 CLAUDE.md is an instructions file published in the GitHub repository ekscrypto/sm3 (10 stars, last pushed 12mo ago), licensed MIT. It adds 3,860 tokens to every session, about $0.0154 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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sm3: Instructions file for Claude Code