ctf-crypto

ljagiello/ctf-skills Security

ctf-crypto is a skill in ljagiello/ctf-skills, last changed 26 Oct 2026. It can handle money, run shell commands, reach the network, name web addresses and pre-approve tools — read the findings before installing.

From the author

Provides cryptography attack techniques for CTF challenges. Use when attacking encryption, hashing, signatures, ZKP, PRNG, or mathematical crypto problems involving RSA, AES, ECC, lattices, LWE, CVP, number theory, Coppersmith, Pollard, Wiener, padding oracle, GCM, key derivation, or stream/block cipher weaknesses.

What it can touch

Handles money
Runs shell commands
Reaches the network
Names web addresses
Pre-approves tools
+2 more
- Names web addresses
- Pre-approves tools

How much a skill can do, not whether it is risky.

Pattern check

1 item to review

Broad tools pre-approved in allowed-tools

R34 · High · SKILL.md:6

Commit a6106aa · 3 Nov 2026

How the check works

Pattern check:1 item to reviewSee it

Install

Each tab says whether it installs commit a6106aa, the one we checked, or the latest version.

OpenCode also looks in .agents/skills/ and ~/.agents/skills/, so use the Any agent steps.

Goose also looks in .agents/skills/ and ~/.agents/skills/, so use the Any agent steps.

Windsurf (Devin Desktop) also looks in .agents/skills/ and ~/.agents/skills/, so use the Any agent steps.

Zed also looks in .agents/skills/ and ~/.agents/skills/, so use the Any agent steps.

Roo Code also looks in .agents/skills/ and ~/.agents/skills/, so use the Any agent steps.

Factory Droid also looks in .agents/skills/ and ~/.agents/skills/, so use the Any agent steps.

Junie also looks in .agents/skills/ and ~/.agents/skills/, so use the Any agent steps.

Amp also looks in .agents/skills/ and ~/.agents/skills/, so use the Any agent steps.

No install command here reaches Kiro. Copy the skill's folder into .kiro/skills/ in your project, or ~/.kiro/skills/ for all your projects. ljagiello/ctf-skills/ctf-crypto (opens in a new tab)

Antigravity also looks in .agents/skills/, so the Any agent steps reach it with This project. For All projects, see where Antigravity looks.

Cline also looks in .claude/skills/, so the Claude Code steps reach it with This project. For All projects, see where Cline looks.

No tab for your agent? Use Any agent for OpenCode, Goose, Windsurf (Devin Desktop), Zed, Roo Code, Factory Droid, Junie and Amp. With This project, Any agent also reaches Antigravity and Claude Code reaches Cline. Kiro needs the folder copied by hand.

Read this before installing: Broad tools pre-approved in allowed-tools — SKILL.md:6

Pinned to commit a6106aa, the one we checked.

From your project's root folder:

tmp="$(mktemp -d)" &&git clone -q --depth 1 --filter=blob:none --no-checkout https://github.com/ljagiello/ctf-skills.git "$tmp" &&git -C "$tmp" fetch -q --depth 1 origin a6106aaf5f1f4eeb6b95908f11c2314c7150dfac &&git -C "$tmp" sparse-checkout set -- ctf-crypto &&git -C "$tmp" checkout -q a6106aaf5f1f4eeb6b95908f11c2314c7150dfac &&mkdir -p .claude/skills &&mkdir .claude/skills/ctf-crypto &&cp -R "$tmp"/ctf-crypto/. .claude/skills/ctf-crypto/ &&rm -rf "$tmp"

If Claude Code was already running and this created the skills folder, run /reload-skills.

Claude Code docs

Pinned to commit a6106aa, the one we checked.

Skills in the Claude apps belong to your account rather than to a project.

Make ctf-crypto.zip, with the skill folder at the top level:

tmp="$(mktemp -d)" &&git clone -q --depth 1 --filter=blob:none --no-checkout https://github.com/ljagiello/ctf-skills.git "$tmp" &&git -C "$tmp" fetch -q --depth 1 origin a6106aaf5f1f4eeb6b95908f11c2314c7150dfac &&git -C "$tmp" sparse-checkout set -- ctf-crypto &&git -C "$tmp" checkout -q a6106aaf5f1f4eeb6b95908f11c2314c7150dfac &&out="$(mktemp -d)" &&cp -R "$tmp"/ctf-crypto "$out"/ctf-crypto &&(cd "$out" && zip -qr - ctf-crypto) > ctf-crypto.zip &&rm -rf "$tmp" "$out"

In Claude, open Customize > Skills, select +, then + Create skill > Upload a skill, and choose ctf-crypto.zip.

On Free, Pro and Max plans, turn on Code execution and file creation (Create and edit files in newer settings) under Settings > Capabilities.

Claude apps docs

Pinned to commit a6106aa, the one we checked.

From your project's root folder:

tmp="$(mktemp -d)" &&git clone -q --depth 1 --filter=blob:none --no-checkout https://github.com/ljagiello/ctf-skills.git "$tmp" &&git -C "$tmp" fetch -q --depth 1 origin a6106aaf5f1f4eeb6b95908f11c2314c7150dfac &&git -C "$tmp" sparse-checkout set -- ctf-crypto &&git -C "$tmp" checkout -q a6106aaf5f1f4eeb6b95908f11c2314c7150dfac &&mkdir -p .agents/skills &&mkdir .agents/skills/ctf-crypto &&cp -R "$tmp"/ctf-crypto/. .agents/skills/ctf-crypto/ &&rm -rf "$tmp"

Codex picks up new skills on its own; restart it if this one does not appear.

Codex docs

Pinned to commit a6106aa, the one we checked.

From your project's root folder:

tmp="$(mktemp -d)" &&git clone -q --depth 1 --filter=blob:none --no-checkout https://github.com/ljagiello/ctf-skills.git "$tmp" &&git -C "$tmp" fetch -q --depth 1 origin a6106aaf5f1f4eeb6b95908f11c2314c7150dfac &&git -C "$tmp" sparse-checkout set -- ctf-crypto &&git -C "$tmp" checkout -q a6106aaf5f1f4eeb6b95908f11c2314c7150dfac &&mkdir -p .cursor/skills &&mkdir .cursor/skills/ctf-crypto &&cp -R "$tmp"/ctf-crypto/. .cursor/skills/ctf-crypto/ &&rm -rf "$tmp"

Cursor docs

Pinned to commit a6106aa, the one we checked.

From your project's root folder:

tmp="$(mktemp -d)" &&git clone -q --depth 1 --filter=blob:none --no-checkout https://github.com/ljagiello/ctf-skills.git "$tmp" &&git -C "$tmp" fetch -q --depth 1 origin a6106aaf5f1f4eeb6b95908f11c2314c7150dfac &&git -C "$tmp" sparse-checkout set -- ctf-crypto &&git -C "$tmp" checkout -q a6106aaf5f1f4eeb6b95908f11c2314c7150dfac &&mkdir -p .github/skills &&mkdir .github/skills/ctf-crypto &&cp -R "$tmp"/ctf-crypto/. .github/skills/ctf-crypto/ &&rm -rf "$tmp"

In a running Copilot CLI session, run /skills reload.

Or install it with gh skill, which also installs the commit we checked. Needs GitHub CLI 2.90 or later.

gh skill install ljagiello/ctf-skills ctf-crypto/SKILL.md@a6106aaf5f1f4eeb6b95908f11c2314c7150dfac --agent github-copilot --scope project

Copilot & VS Code docs

Pinned to commit a6106aa, the one we checked.

From your project's root folder:

tmp="$(mktemp -d)" &&git clone -q --depth 1 --filter=blob:none --no-checkout https://github.com/ljagiello/ctf-skills.git "$tmp" &&git -C "$tmp" fetch -q --depth 1 origin a6106aaf5f1f4eeb6b95908f11c2314c7150dfac &&git -C "$tmp" sparse-checkout set -- ctf-crypto &&git -C "$tmp" checkout -q a6106aaf5f1f4eeb6b95908f11c2314c7150dfac &&mkdir -p .gemini/skills &&mkdir .gemini/skills/ctf-crypto &&cp -R "$tmp"/ctf-crypto/. .gemini/skills/ctf-crypto/ &&rm -rf "$tmp"

In a running session, run /skills reload.

Or use Gemini CLI’s own installer. Installs the latest version, not the one we checked.

gemini skills install https://github.com/ljagiello/ctf-skills.git --path ctf-crypto --scope workspace

Gemini CLI docs

Pinned to commit a6106aa, the one we checked.

OpenCode, Goose, Windsurf (Devin Desktop), Zed, Roo Code, Factory Droid, Junie, Amp and Antigravity read .agents/skills in a project.

From your project's root folder:

tmp="$(mktemp -d)" &&git clone -q --depth 1 --filter=blob:none --no-checkout https://github.com/ljagiello/ctf-skills.git "$tmp" &&git -C "$tmp" fetch -q --depth 1 origin a6106aaf5f1f4eeb6b95908f11c2314c7150dfac &&git -C "$tmp" sparse-checkout set -- ctf-crypto &&git -C "$tmp" checkout -q a6106aaf5f1f4eeb6b95908f11c2314c7150dfac &&mkdir -p .agents/skills &&mkdir .agents/skills/ctf-crypto &&cp -R "$tmp"/ctf-crypto/. .agents/skills/ctf-crypto/ &&rm -rf "$tmp"

Or use the skills CLI from skills.sh. Installs the latest version, not the one we checked. The skills CLI reports installs to skills.sh unless you set DISABLE_TELEMETRY=1.

npx skills@1.7.4 add ljagiello/ctf-skills --skill ctf-crypto

Agent Skills docs

Read SKILL.md first

MIT

Licence

3.6k

Repo stars

Folder last changed

Publisher

Files

Checked

3 Nov 2026

What it can touch

From the files and frontmatter at commit a6106aa. This is how much a skill can do, not whether it is risky.

Handles money
It handles wallets, seed phrases, token approvals, trading keys or referral links.
exotic-crypto-2.md:276 (opens in a new tab)
Runs shell commands
Its instructions or files give the agent commands to run on your computer.
Reaches the network
It sends or fetches data over the internet, for example with curl, an HTTP library or a package install.
Names web addresses
It mentions outside web addresses the agent may visit. We list them but don't follow them.
Outside links we did not follow
Pre-approves tools
Its allowed-tools field lists tools the agent may use without asking you first, in agents that honour it.
SKILL.md:6 (opens in a new tab)

Pattern check

Pattern check: 1 item to review · commit a6106aa · 3 Nov 2026

R34 · HighBroad tools pre-approved in allowed-tools
SKILL.md:6 (opens in a new tab)
```
allowed-tools: Bash Read Write Edit Glob Grep Task WebFetch WebSearch
```

We checked every text file in this skill, at commit a6106aa on 3 Nov 2026, against 45 published patterns such as download-and-run commands, hidden text and credential access. We don't run the skill, we don't read the web pages it points to, and we can't judge everything its instructions might lead an agent to do. In published tests, pattern checks like this one missed most malicious skills. Read the skill before you install it — especially anything it asks you to download or run.

How the check works Report an incorrect finding

Show 4 more

http://target/reset/
https://gitlab.com/jix/neca.git
https://github.com/crocs-muni/roca
https://github.com/resilar/crchack

Format check

Each agent reads SKILL.md a little differently. We check the file against each one's published rules; we don't run the skill in any agent.

Agent Skills specPasses with warnings
The open format from agentskills.io, held to the strictest version of each rule among the agents we check.
- Warning
  The body is about 10,347 tokens (approx.); the spec suggests under 5,000. B2
  Fix: Move detail into reference files that the agent reads only when needed.
Claude CodePasses with warnings
Claude Code reads its own extra fields, ignores unknown ones, and still loads a skill whose frontmatter is broken, without its fields.
- Warning
  metadata reuses field names: user-invocable. Claude Code asks that metadata keys not repeat fields such as paths. O4
  Fix: Rename those keys, for example with your organisation as a prefix.
- Note
  The body is about 10,347 tokens (approx.); the spec suggests under 5,000. After compaction Claude Code keeps only the first 5,000 tokens of a skill. B2
  Fix: Move detail into reference files that the agent reads only when needed.
Claude apps & API uploadPasses
Uploading to claude.ai or the Claude API, or packaging with Anthropic's script, accepts only the six spec fields and stops on anything else.
- Note
  The description is 316 characters. The claude.ai Help Center says 200 at most, though Anthropic's API docs and validator allow 1,024. D4
  Fix: If the claude.ai upload refuses it, trim the description to 200 characters.
- Note
  The body is about 10,347 tokens (approx.); the spec suggests under 5,000. Anthropic's guidance says the same. B2
  Fix: Move detail into reference files that the agent reads only when needed.
OpenAI (Codex & API)Passes
VS Code & CopilotPasses

SKILL.md

Read SKILL.md on GitHub

Files

20 files

Path	Size
SKILL.md (opens in a new tab)	41.1 KB
advanced-math.md (opens in a new tab)	40.4 KB
classic-ciphers.md (opens in a new tab)	28.5 KB
dh-attacks.md (opens in a new tab)	6.3 KB
ecc-attacks.md (opens in a new tab)	40.9 KB
exotic-crypto-2.md (opens in a new tab)	19.6 KB
exotic-crypto.md (opens in a new tab)	36.8 KB
historical.md (opens in a new tab)	4.5 KB
lattice-and-lwe.md (opens in a new tab)	33.1 KB
modern-ciphers-2.md (opens in a new tab)	29.2 KB
modern-ciphers-3.md (opens in a new tab)	27.2 KB
modern-ciphers-4.md (opens in a new tab)	24.2 KB
modern-ciphers.md (opens in a new tab)	35.5 KB
post-quantum.md (opens in a new tab)	4.2 KB
prng-attacks.md (opens in a new tab)	12.2 KB
prng.md (opens in a new tab)	42.5 KB
rsa-attacks-2.md (opens in a new tab)	46.1 KB
rsa-attacks.md (opens in a new tab)	57.3 KB
stream-ciphers.md (opens in a new tab)	33.2 KB
zkp-and-advanced.md (opens in a new tab)	20.7 KB

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At a glance

What it can touch

Pattern check

Install

Claude Code

Claude apps

Codex

Cursor

Copilot & VS Code

Gemini CLI

Any agent

What it can touch

Pattern check

Outside links we did not follow

Format check

SKILL.md

Files

More from ljagiello/ctf-skills

Other Security skills