Ctf Osint
ljagiello/ctf-skills
Provides open source intelligence techniques for CTF challenges.
Reconstruct CTF key, serial, and flag verifiers using known plaintext, repeating XOR, encoded constants, bytecode replacement, hash constraints, SMT, and bounded brute force.
Install Ctf Key Recovery
$ npx skills add manyuegong33/r0crawl_skills --skill ctf-key-recovery -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install manyuegong33/r0crawl_skills ctf-key-recovery --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/manyuegong33/r0crawl_skills.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/ctf-key-recovery .claude/skills/ctf-key-recovery && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "ctf-key-recovery" agent skill from https://github.com/manyuegong33/r0crawl_skills/tree/main/skills/ctf-key-recovery into .claude/skills/ctf-key-recovery/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ctf-key-recovery", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/manyuegong33/r0crawl_skills/tree/main/skills/ctf-key-recoveryType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add manyuegong33/r0crawl_skills --skill ctf-key-recovery -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install manyuegong33/r0crawl_skills ctf-key-recovery --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/manyuegong33/r0crawl_skills.git skills-src && mkdir -p .agents/skills && cp -r skills-src/skills/ctf-key-recovery .agents/skills/ctf-key-recovery && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "ctf-key-recovery" agent skill from https://github.com/manyuegong33/r0crawl_skills/tree/main/skills/ctf-key-recovery into .agents/skills/ctf-key-recovery/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ctf-key-recovery", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add manyuegong33/r0crawl_skills --skill ctf-key-recovery -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install manyuegong33/r0crawl_skills ctf-key-recovery --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/manyuegong33/r0crawl_skills.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/skills/ctf-key-recovery .cursor/skills/ctf-key-recovery && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "ctf-key-recovery" agent skill from https://github.com/manyuegong33/r0crawl_skills/tree/main/skills/ctf-key-recovery into .cursor/skills/ctf-key-recovery/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ctf-key-recovery", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/manyuegong33/r0crawl_skills.git --path skills/ctf-key-recovery--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add manyuegong33/r0crawl_skills --skill ctf-key-recovery -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install manyuegong33/r0crawl_skills ctf-key-recovery --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/manyuegong33/r0crawl_skills.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/skills/ctf-key-recovery .gemini/skills/ctf-key-recovery && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "ctf-key-recovery" agent skill from https://github.com/manyuegong33/r0crawl_skills/tree/main/skills/ctf-key-recovery into .gemini/skills/ctf-key-recovery/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ctf-key-recovery", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install manyuegong33/r0crawl_skills ctf-key-recoveryInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add manyuegong33/r0crawl_skills --skill ctf-key-recovery -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/manyuegong33/r0crawl_skills.git skills-src && mkdir -p .github/skills && cp -r skills-src/skills/ctf-key-recovery .github/skills/ctf-key-recovery && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "ctf-key-recovery" agent skill from https://github.com/manyuegong33/r0crawl_skills/tree/main/skills/ctf-key-recovery into .github/skills/ctf-key-recovery/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ctf-key-recovery", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add manyuegong33/r0crawl_skills --skill ctf-key-recovery -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install manyuegong33/r0crawl_skills ctf-key-recovery --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/manyuegong33/r0crawl_skills.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/skills/ctf-key-recovery .opencode/skills/ctf-key-recovery && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "ctf-key-recovery" agent skill from https://github.com/manyuegong33/r0crawl_skills/tree/main/skills/ctf-key-recovery into .opencode/skills/ctf-key-recovery/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ctf-key-recovery", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
ctf-key-recovery- GitHub stars
- 312
- Token cost
- ~434 tokens
- SKILL.md length
- 166 words
- Files
- 4 (incl. scripts, references)
- Skills in repo
- 9
- Repo updated
- First seen
- Licence
- None found
At a glance
Reconstruct CTF key, serial, and flag verifiers using known plaintext, repeating XOR, encoded constants, bytecode replacement, hash constraints, SMT, and bounded brute force.
- Works in 5 steps: algebraic inversion → known-plaintext constraints → printable/format constraints → …
- A reverse challenge requests a key
- SKILL.md covers Reconstruct the exact verifier, Use the cheapest invertible…, Validate twice and Quality gates
- Runs Python scripts from its folder
What it does
Ctf Key Recovery is an agent skill from manyuegong33/r0crawl_skills. Reconstruct CTF key, serial, and flag verifiers using known plaintext, repeating XOR, encoded constants, bytecode replacement, hash constraints, SMT, and bounded brute force. Use when a reverse challenge requests a key or serial and the verifier or encrypted target bytes can be recovered statically or dynamically.
Its SKILL.md is about 430 tokens, which your agent loads only when the skill is triggered. The skill folder holds 6 other files, including scripts and reference files (for example `agents/openai.yaml`, `references/verifier-checklist.md` and `scripts/recover_repeating_xor.py`).
It sits in Security, covering Capture the flag. The repository describes itself as: r0crawlskills is a massive reverse-engineering skill arsenal for web, Android, iOS, Frida, native binaries, protocols, malware, firmware, and anti-analysis—built for beginners…
When your agent uses it
- A reverse challenge requests a key
- Serial and the verifier
- Encrypted target bytes can be recovered statically
Example prompts
- “/ctf-key-recovery”
Requirements
- Python 3
Workflow steps
5 steps, taken from the first numbered list in SKILL.md.
- algebraic inversion
- known-plaintext constraints
- printable/format constraints
- SMT solver
- bounded brute force
What it can do on your machine
Read from SKILL.md and the folder at commit b9eb545. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
Ships 1 file in scripts/ (Python), which the agent can run.
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Context cost
Ctf Key Recovery loads about 434 tokens when it runs, and up to ~568 if it reads all its reference files. Until then it costs about 83 tokens; SKILL.md has 166 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
Safety
Auto-check passed
The automated check found no risky patterns in SKILL.md.
Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); the scripts in this folder are not scanned.
SKILL.md
Without a licence we can't republish the file, so here is its outline and opening line. It has 166 words (~434 tokens).
“Write down input normalization, encoding, required length, transforms, comparison bytes, success condition, and retry behavior. Separate presentation decoding from authentication logic; similar XOR loops may use different keys.”
- name
- ctf-key-recovery
Files
SKILL.md and 3 other files (scripts, references) in skills/ctf-key-recovery of manyuegong33/r0crawl_skills.
- SKILL.md
- agents/openai.yaml
- references/verifier-checklist.md
- scripts/recover_repeating_xor.py
Open the folder on GitHubat commit b9eb545
Compare with similar skills
Ctf Key Recovery next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| Ctf Key Recovery this skillmanyuegong33/r0crawl_skills | 312 | — | ~434 | Automated safety check: Pass | None | |
| Ctf Osintljagiello/ctf-skills | 3.4k | 1 repos | ~2.3k | Automated safety check: Notes | MIT | |
| Helloctf SkillProbiusOfficial/Hello-CTF | 4.2k | — | ~387 | Automated safety check: Pass | GPL-3.0 | |
| Secknowledge SkillPa55w0rd/secknowledge-skill | 425 | — | ~2.7k | Automated safety check: Pass | None | |
| Vuln Researchtanweai/xianzhi-research | 185 | — | ~847 | Automated safety check: Pass | None | |
| Alibabacloud Ecs Sec Kernelaliyun/alibabacloud-ecs-troubleshoot-skills | 148 | — | ~2.4k | Automated safety check: Notes | Apache-2.0 |
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Related
Categories
Questions about Ctf Key Recovery
What does Ctf Key Recovery do?
Reconstruct CTF key, serial, and flag verifiers using known plaintext, repeating XOR, encoded constants, bytecode replacement, hash constraints, SMT, and bounded brute force. Ctf Key Recovery is an agent skill from manyuegong33/r0crawl_skills. Reconstruct CTF key, serial, and flag verifiers using known plaintext, repeating XOR, encoded constants, bytecode replacement, hash constraints, SMT, and bounded brute force.
When should I use Ctf Key Recovery?
Ctf Key Recovery fits situations like: A reverse challenge requests a key; serial and the verifier; encrypted target bytes can be recovered statically.
How do I install Ctf Key Recovery in Claude Code?
Run `npx skills add manyuegong33/r0crawl_skills --skill ctf-key-recovery -a claude-code`. Or copy the skill folder (skills/ctf-key-recovery in manyuegong33/r0crawl_skills) into .claude/skills/ctf-key-recovery in your project. Claude Code loads it when a task matches its description.
How do I install Ctf Key Recovery in Codex?
Run `npx skills add manyuegong33/r0crawl_skills --skill ctf-key-recovery -a codex`. Or copy the skill folder (skills/ctf-key-recovery in manyuegong33/r0crawl_skills) into .agents/skills/ctf-key-recovery in your project. Codex loads it when a task matches its description.
Can I use Ctf Key Recovery in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add manyuegong33/r0crawl_skills --skill ctf-key-recovery -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/ctf-key-recovery, .gemini/skills/ctf-key-recovery, .github/skills/ctf-key-recovery and .opencode/skills/ctf-key-recovery in your project.
What does Ctf Key Recovery need to run?
Going by SKILL.md and its folder, Ctf Key Recovery needs Python for the scripts in its folder. Our summary lists: Python 3.
Does Ctf Key Recovery access the network?
SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.
Is Ctf Key Recovery safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. The check reads SKILL.md only: the scripts in the folder are not scanned, so read them before running anything.
What licence does Ctf Key Recovery use?
No licence was found for Ctf Key Recovery or its repository. Without one, default copyright applies: ask the author before reusing or redistributing it.
How many tokens does Ctf Key Recovery use?
About 434 tokens (SKILL.md is roughly 1.7k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 134 tokens, read only when the agent opens those files.
What are the alternatives to Ctf Key Recovery?
Skills that share tags, products or a category with Ctf Key Recovery: Ctf Osint (ljagiello/ctf-skills, 3.4k stars), Helloctf Skill (ProbiusOfficial/Hello-CTF, 4.2k stars), Secknowledge Skill (Pa55w0rd/secknowledge-skill, 425 stars) and Vuln Research (tanweai/xianzhi-research, 185 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Ctf Key Recovery?
manyuegong33 (a GitHub user) maintains it in manyuegong33/r0crawl_skills, which has 312 GitHub stars. The repository holds 9 skills in this directory. The repository was last updated on September 20, 2026.
Source: manyuegong33/r0crawl_skills on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.