vector-forge — Claude Code skill for crypto test vectors
This skill uses mutation testing to find gaps in tests for cryptographic implementations and propose vectors for uncovered cases. Use it to assess an existing test suite.
npx skills add trailofbits/skills --skill vector-forge -a claude-codeWhat vector-forge does
vector-forge helps identify parts of a cryptographic implementation that current test vectors do not exercise. The agent finds implementations of an algorithm or protocol, prepares a test harness, and runs mutation testing. It then examines mutants that survive the tests and creates vectors aimed at those cases.
After adding vectors, the tests run again and the results are compared with the baseline. This shows whether the new vectors changed how many mutations the suite detects. The project needs an implementation, a harness that feeds it vectors, and a mutation testing framework for its language. trailmark is also required. Without an implementation, there is no code to mutate.
What it helps with
- find implementation paths missed by existing test vectors
- assess a test suite with mutation testing
- inspect mutants that survive the current tests
- create vectors for uncovered cases
- compare mutation results before and after adding vectors
Example prompts for the agent
- Check which parts of this implementation the current test vectors miss.
- Find mutants that survive the tests and suggest vectors to exercise those cases.
- Compare mutation testing results before and after adding new test vectors.
How to install vector-forge
1Skills CLI (Vercel)
npx skills add trailofbits/skills --skill vector-forge -a claude-code2Manually: put the files in place
~/.claude/skills/vector-forge/SKILL.mdCopy the whole skill folder; for one project use .claude/skills/vector-forge/
1Skills CLI (Vercel)
npx skills add trailofbits/skills --skill vector-forge -a codex2Manually: put the files in place
.agents/skills/vector-forge/SKILL.mdFor all projects use ~/.agents/skills/
1Skills CLI (Vercel)
npx skills add trailofbits/skills --skill vector-forge -a cursor2Manually: put the files in place
.cursor/skills/vector-forge/SKILL.mdCursor also reads .agents/skills/ and .claude/skills/
1GitHub CLI
gh skill install trailofbits/skills vector-forge2Manually: put the files in place
.github/skills/vector-forge/SKILL.md1Skills CLI (Vercel)
npx skills add trailofbits/skills --skill vector-forge -a gemini-cli2Platform CLI
gemini skills install https://github.com/trailofbits/skills --path plugins/trailmark/skills/vector-forgeManually: put the files in place
.devin/skills/vector-forge/SKILL.mdThe legacy .windsurf/skills/ path still works
Skills CLI (Vercel)
npx skills add trailofbits/skills --skill vector-forge -a opencodeClaude.ai
Zip the folder and upload it in Settings → Capabilities → Skills
Step by step, with commands for each platform: How to install skills in Claude Code: five ways
Questions about vector-forge
How do I install vector-forge in Claude Code?
Run npx skills add trailofbits/skills --skill vector-forge -a claude-code. The skill file is placed at ~/.claude/skills/vector-forge/SKILL.md.
What does vector-forge do?
It uses mutation testing to find gaps in tests for cryptographic implementations, then creates vectors aimed at those gaps. It compares results before and after adding the vectors.
What does vector-forge need to run?
You need an implementation of the target algorithm, a harness that feeds it test vectors, and a mutation testing framework for its language. trailmark is also required.
