Ctf Key Recovery

Community

manyuegong33

ctf-key-recovery

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.

Overview

Publisher	manyuegong33
Repository	`r0crawl_skills`
Skill name	`ctf-key-recovery`
Stars	340
Forks	120
Bundled files	3
Links	Skill source Repository

Markdown instructions
A SKILL.md file the model loads on demand, so it only costs tokens when a request actually matches.
Works with any LLM
AI skills are plain Markdown, not provider-specific code, so this works with GPT, Claude, Gemini, Grok, or a local model.
3 bundled files
Scripts, templates, and references the model can read while it works. Files are read-only and never executed.
Open source
Published by manyuegong33 on GitHub. Read the source before you install it.

Installation

Install the Ctf Key Recovery AI skill in TypingMind to use it with any LLM, or drop it into another agent that reads SKILL.md.

Install in TypingMind

TypingMind installs a skill straight from its GitHub folder — it reads SKILL.md, bundles the resource files, and stores the result locally.

Open the app and go to Plugins → Skills.
Choose "Install from GitHub".
Paste the skill folder URL below and confirm.
https://github.com/manyuegong33/r0crawl_skills/tree/main/skills/ctf-key-recovery
Enable the skill in any chat where you want it available.

Plugins → Skills → Add skill → From GitHub URL, then paste the folder URL and press Continue.

Install in another agent

Any agent that reads the Agent Skills format can use this skill — copy the folder into that agent's skills directory.

Claude Code — .claude/skills

git clone --depth 1 https://github.com/manyuegong33/r0crawl_skills.git /tmp/r0crawl_skills
mkdir -p .claude/skills
cp -r /tmp/r0crawl_skills/skills/ctf-key-recovery .claude/skills/ctf-key-recovery

Restart Claude Code after copying so it picks up the new skill.

Use it in TypingMind

Enable Ctf Key Recovery in any TypingMind chat and the model takes it from there. Its name and description sit in the system prompt, and the moment a request matches, the model loads the full instructions itself — you never invoke it by hand, and it costs no tokens until it is actually used.

The model loads Ctf Key Recovery on its own as soon as a request matches it.

Works with any AI model

AI skills are plain Markdown instructions rather than provider-specific code, so Ctf Key Recovery is not tied to the model it was written for. Install it once in TypingMind and use it with GPT-5, Claude, Gemini, Grok, DeepSeek, Mistral, Llama, or a local model you run yourself — all on your own API keys.

Loaded only when it is needed
The system prompt carries just the name and description. The instructions are fetched on the first matching request, so an idle skill costs nothing.
Switch models mid-chat
Because the skill is instructions rather than code, changing model does not break it — the next model reads the same SKILL.md.

Skill instructions

This is the SKILL.md content the model loads. Read it before installing — a skill is instructions your model will follow.

CTF Key Recovery

Reconstruct the exact verifier

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.

Use the cheapest invertible relation

For repeating XOR with period p:

text
cipher[i] = plain[i] XOR key[i mod p]
key[i mod p] = cipher[i] XOR plain[i]

Recover every key position from known plaintext and reject inconsistent positions. Run scripts/recover_repeating_xor.py for a reproducible derivation.

Escalate only as needed:

algebraic inversion
known-plaintext constraints
printable/format constraints
SMT solver
bounded brute force

See references/verifier-checklist.md before declaring success.

Validate twice

Re-encrypt or replay the recovered key against the reconstructed verifier.
Run the original challenge through its real input path and observe the success branch.

Record the raw key separately from any platform wrapper such as flag{...}.

Quality gates

Do not treat a plaintext-looking substring as the answer without verifier parity.
Do not mix display constants with comparison constants.
Preserve byte order, signedness, encoding, and terminators.
Test wrong length, one-byte mutation, and the recovered key.

Bundled files

The model reads these on demand while the skill is loaded. They are exposed as readable files and are never executed.

Frequently asked questions

What does the Ctf Key Recovery AI skill do?

Why use Ctf Key Recovery on TypingMind?

Because you install it once and use it with any model. Ctf Key Recovery is plain Markdown rather than provider-specific code, so the same skill runs on GPT-5, Claude, Gemini, Grok, or a local model — and you can switch model mid-chat without it breaking. TypingMind runs on your own API keys, so you pay providers directly instead of a per-seat subscription, and your skills and chats stay in your own storage.

How do I install Ctf Key Recovery in TypingMind?

Open Plugins → Skills → Install from GitHub in TypingMind and paste https://github.com/manyuegong33/r0crawl_skills/tree/main/skills/ctf-key-recovery. TypingMind reads its SKILL.md and bundles its files and installs it as a skill you can enable per chat.

Which AI models can use Ctf Key Recovery?

Any model you connect in TypingMind. AI skills are plain Markdown instructions rather than provider-specific code, so GPT, Claude, Gemini, Grok, and local models can all load this skill when a request matches it.

How many AI models can I use with Ctf Key Recovery?

As many as you like. As long as a model supports skills, you can use Ctf Key Recovery with it — GPT, Claude, Gemini, Grok, DeepSeek, Mistral, Llama and more — all on TypingMind with your own API keys.

Is the Ctf Key Recovery AI skill free?

It is published on GitHub by manyuegong33. Check the repository for licensing terms. You only pay your own AI provider for the tokens you use.

What are AI skills?

An AI skill is a reusable instruction bundle that teaches an AI model how to do one specific task. It follows the open Agent Skills format: a SKILL.md file with a name and description, plus any scripts, templates or reference files the model may need. The model reads the instructions only when your request matches the skill, so an installed skill costs nothing until it is used.

How are AI skills different from plugins or MCP servers?

A plugin or MCP server gives a model new tools to call — code that runs somewhere and returns a result. An AI skill gives the model knowledge and process instead: how to approach a task, which steps to follow, what good output looks like. Skills are plain Markdown, so they need no server, no API key and no runtime, and they work with any model.

View all

Test Audit

openclaw

OrganizationPopular

Invoke whenever writing, changing, reviewing, or sweeping tests. Authoring gate for new tests plus audit workflow for low-value, implementation-coupled, or duplicative tests and the test-only…

Feishu Perm

Feishu collaborator and permission workflows. Activate when the user explicitly asks to inspect or change sharing, permissions, or collaborators.

Block Kit

Use proactively for structured or interactive Slack replies, and when asked to author or validate native Slack Block Kit JSON.

1password

Set up and use 1Password CLI for sign-in, desktop integration, and reading or injecting secrets.

Overview

Installation

Install in TypingMind

Install in another agent

Use it in TypingMind

Works with any AI model

Skill instructions

CTF Key Recovery

Reconstruct the exact verifier

Use the cheapest invertible relation

Validate twice

Quality gates

Bundled files

Frequently asked questions

Related AI Skills

Set up your own AI workspace now