ctf-crypto SKILL.md skillA

ctf-crypto from ljagiello/ctf-skills is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.

Install it, pinned

mdr add ljagiello/ctf-skills/ctf-crypto@git:20261027.2388a3b

Pins git:20261027.2388a3b in mdr.lock. Pin the fingerprint instead.

Audit grade: A, 17 of 17 checks passed
Kind: SKILL.md skill
Repository: ljagiello/ctf-skills
Path: ctf-crypto/SKILL.md
Versions recorded: 6
Latest version: git:20261027.2388a3b, committed Oct 27, 2026
First version recorded: Apr 3, 2026
Size: 42,070 bytes
Repository stars: 3,657
License: MIT

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.

Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.

What the file says

# CTF Cryptography

Quick reference for crypto CTF challenges. Each technique has a one-liner here; see supporting files for full details with code.

## Prerequisites

**Python packages (all platforms):**
```bash
pip install pycryptodome z3-solver sympy gmpy2 hashpumpy fpylll py_ecc
# Coppersmith (optional): pip install coppersmith
# Alternative Coppersmith lib: git clone https://github.com/jvdsn/crypto-attacks ~/.ctf-tools/crypto-attacks && pip install -r ~/.ctf-tools/crypto-attacks/requirements.txt
```

**Linux (apt):**
```bash
apt install hashcat
```

**macOS (Homebrew):**
```bash
brew install hashcat
```

**Manual install:**
- SageMath (optional — only for legacy Sage fallback snippets (collapsed sections)) — Linux: `apt install sagemath`, macOS: `brew install --cask sage`
- RsaCtfTool — `git clone https://github.com/RsaCtfTool/RsaCtfTool` (automated RSA attacks)
- crypto-attacks (Coppersmith) — `git clone https://github.com/jvdsn/crypto-attacks ~/.ctf-tools/crypto-attacks` + `pip install -r ~/.ctf-tools/crypto-attacks/requirements.txt` (alternative to `pip install coppersmith`)

> **Note:** `gmpy2` requires libgmp — Linux: `apt install libgmp-dev`, macOS: `brew install gmp`.
…

Read the whole file at its exact version.

How to install

The exact contents, by fingerprint

mdr add ljagiello/ctf-skills/ctf-crypto@sha256:cf87a3ed7fbb7758

The line at the top of this page pins the label git:20261027.2388a3b, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.

Badge

[![mdr](https://markdownregistry.com/badge/art_u42qk5tnkhgdxkcr.svg)](https://markdownregistry.com/a/art_u42qk5tnkhgdxkcr)

4 badge image fetches in 30 days. What the badge shows.

Versions

The registry has recorded 6 versions of this file, between Apr 3, 2026 and Oct 27, 2026, about one every 41 days.

version	committed	commit	size	audit
git:20261027.2388a3b latest	2026-10-27	2388a3b	42,070 B	A	view · diff
git:20260912.61c2efe	2026-09-12	61c2efe	42,044 B	A	view · diff
git:20260417.b80ec3f	2026-04-17	b80ec3f	38,930 B	A	view · diff
git:20260414.2fddcde	2026-04-14	2fddcde	38,918 B	A	view · diff
git:20260413.730d82f	2026-04-13	730d82f	37,951 B	A	view · diff
git:20260403.008fb99	2026-04-03	008fb99	37,685 B	A	view

Audit of the latest version

A 17 of 17 checks passed. Fixed automatic checks with no AI involved, so the same checks give the same answer every run.

pass: Frontmatter block present
pass: Frontmatter declares a name
pass: Frontmatter declares a description
pass: Size between 200 bytes and 200 KB (42070 bytes)
pass: No zero-width or bidi control characters
pass: No instruction hidden inside an HTML comment
pass: No link to an exfiltration or paste host
pass: No credential-shaped string
pass: No instruction to send local credentials anywhere
pass: No text hidden with inline styles
pass: No prompt-injection phrasing
pass: No curl or wget piped into a shell
pass: No recursive delete of root, home or parent
pass: No instruction to read or print local credentials
pass: No base64 blob over 200 characters
pass: No link to a raw IP address
pass: No script tag

Source

GitHub

ljagiello/ctf-skills · 3,657 stars · license MIT · pushed 2026-11-06 · branch main

API

GET https://markdownregistry.com/api/v1/artifacts/art_u42qk5tnkhgdxkcr
GET https://markdownregistry.com/api/v1/resolve?ref=ljagiello/ctf-skills/ctf-crypto
GET https://markdownregistry.com/api/v1/blob/cf87a3ed7fbb77585506546788025a43ff7f53dec99cab6d803a0134e17a4589

Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.

Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.

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