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ctf-crypto SKILL.md skillA

This file is byte-identical to the first copy the registry indexed, one of 3 indexed copies. Same content hash, so the same checks give both the same grade.

ctf-crypto from cyr1s-dev/lynceus is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.

Install it, pinned

mdr add cyr1s-dev/lynceus/ctf-crypto@git:20260929.223300f

Pins git:20260929.223300f in mdr.lock. Pin the fingerprint instead.

Audit grade: A, 17 of 17 checks passed
Kind: SKILL.md skill
Repository: cyr1s-dev/lynceus
Path: resources/skills/ctf-crypto/SKILL.md
Versions recorded: 1
Latest version: git:20260929.223300f, committed Sep 29, 2026
Size: 42,044 bytes
Repository stars: 11
License: AGPL-3.0

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 cyr1s-dev/lynceus/ctf-crypto@sha256:3f73227dbf2b12c0

The line at the top of this page pins the label git:20260929.223300f, 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_ujdpbvfceewqbteb.svg)](https://markdownregistry.com/a/art_ujdpbvfceewqbteb)

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

Versions

The registry has recorded 1 version of this file, committed on Sep 29, 2026.

version	committed	commit	size	audit
git:20260929.223300f latest	2026-09-29	223300f	42,044 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 (42044 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

cyr1s-dev/lynceus · 11 stars · license AGPL-3.0 · pushed 2026-09-29 · branch main

API

GET https://markdownregistry.com/api/v1/artifacts/art_ujdpbvfceewqbteb
GET https://markdownregistry.com/api/v1/resolve?ref=cyr1s-dev/lynceus/ctf-crypto
GET https://markdownregistry.com/api/v1/blob/3f73227dbf2b12c063d8df68a207430dfe1113f290a9da0fe2715f73fc74259c

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.