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ctf-crypto
76 / 100 · Review before installing
Check before installing. Some of what it can do is expected: a coding skill usually runs build and test commands.
By ljagiello/ctf-skills (GitHub) · coding · 3,679 stars · scanned at commit e79be29
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.
Works with any agent that supports SKILL.md skills.
What this skill can do
Downloads and installs other software
This is disclosed by the author in the skill's SKILL.md or README.
Found in 12 places.
Show 9 more
- ctf-crypto/SKILL.md, line 36
- SageMath (optional — only for legacy Sage fallback snippets (collapsed sections)) — Linux: `apt install sagemath`, macOS: `brew install --cask sage` - ctf-crypto/SKILL.md, line 38
- crypto-attacks (Coppersmith) — `git clone https://github.com/jvdsn/crypto-attacks ~/.ctf-tools/crypto-attacks` + `pip install -r ~/.ctf-tools/crypto-attacks/r - ctf-crypto/SKILL.md, line 40
> **Note:** `gmpy2` requires libgmp — Linux: `apt install libgmp-dev`, macOS: `brew install gmp`. - ctf-crypto/SKILL.md, line 330
- **Python:** `pip install pycryptodome z3-solver sympy gmpy2` - ctf-crypto/advanced-math.md, line 376
Pure-Python Coppersmith -- same `fplll` as Sage, `uv` only. Keep `X` explicit, `beta=0.5`, monic check `lc==1` else `inv_lc`. `flatter` optional for `dim>100` ( - ctf-crypto/rsa-attacks-2.md, line 586
pip install roca-detect - ctf-crypto/rsa-attacks.md, line 134
**When to use:** Very large `e` (close to `n`) often indicates small `d`. Also try `owiener` Python package: `pip install owiener`. - ctf-crypto/rsa-attacks.md, line 487
raise ImportError("fpylll not installed; pip install fpylll or use tiny X brute-force") from e - ctf-crypto/rsa-attacks.md, line 1029
raise ImportError("fpylll not installed; pip install fpylll") from e
Runs commands on your computer
This is disclosed by the author in the skill's SKILL.md or README. Expected for a coding skill.
Found in 7 places.
Show 4 more
- ctf-crypto/SKILL.md, line 78
python3 -c "from Crypto.Util.number import *; n=<N>; print(f'bits={n.bit_length()}')" - ctf-crypto/classic-ciphers.md, line 526
result = subprocess.run(['file', 'decrypted.pdf'], capture_output=True, text=True) - ctf-crypto/ecc-attacks.md, line 874
subprocess.run(["fastcoll", "-p", prefix_file, "-o", "col1", "col2"]) - ctf-crypto/rsa-attacks-2.md, line 1000
cmd = subprocess.check_output(['./crchack/crchack', '/tmp/cmd', hex(target_crc)])
Changes files outside its own folder
The author does not mention this.
Found in 1 place.
Connects to the internet
This is disclosed by the author in the skill's SKILL.md or README.
Found in 2 places.
Safer alternatives
Low-risk skills in the same category (coding) that look related. Check that one does what you need.
Install
Paste this into your terminal. It downloads exactly the version we scanned, not whatever is newest.
if [ -e ~/.agents/skills/'ctf-crypto' ] || [ -L ~/.agents/skills/'ctf-crypto' ]; then echo 'A skill folder named ctf-crypto already exists — not replacing it' >&2; false; else d=$(mktemp -d) && git clone --quiet --filter=blob:none --no-checkout 'https://github.com/ljagiello/ctf-skills' "$d" && git -C "$d" checkout --quiet 'e79be2925d1612e8a97070d6201e300286672370' -- 'ctf-crypto' && mkdir -p ~/.agents/skills && cp -R "$d"/'ctf-crypto' ~/.agents/skills/'ctf-crypto' && rm -rf "$d"; fi
Codex reads ~/.agents/skills directly. For Claude Code, Cursor, Copilot, Gemini CLI, Antigravity or OpenCode, also link it. For Claude Code: ln -s ~/.agents/skills/'ctf-crypto' ~/.claude/skills/'ctf-crypto' (other agents: ~/.cursor/skills, ~/.copilot/skills, ~/.gemini/skills, ~/.gemini/config/skills, ~/.config/opencode/skills). Or install through the finder skill, which does both.
Badge for your README
The badge for ljagiello/ctf-skills shows the score of its lowest-scoring skill.
[](https://zalavijaysinh.github.io/skilltrust/repos/ljagiello/ctf-skills/)
Score history
| Date | Version | Score |
|---|
| 2026-11-11 | e79be29 | 76 |
| 2026-11-08 | 2ad85d3 | 76 |
| 2026-11-07 | 2ad85d3 | 56 |