Feal Differential Cryptanalysis

Q: What is a Claude Code skill and how does the Feal Differential Cryptanalysis skill fit in?

A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. Feal Differential Cryptanalysis is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Security category. Learn more at https://claudskills.com/learn/what-is-skill-md/.

Category: Security · Sub-category: red-team · Last updated: 2026-08-18

Guidance for implementing differential cryptanalysis attacks on FEAL (Fast Data Encipherment Algorithm) and similar block ciphers. This skill should be used when tasks involve recovering round keys, implementing differential attacks, exploiting cipher weaknesses, or performing cryptanalysis on Feistel network ciphers. Applicable to CTF challenges and educational cryptanalysis exercises.

Security AStatic scan found no risk patternsHow grading works ›

What this skill does

Feal Differential Cryptanalysis is a community-contributed Claude Code skill in the red-team sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/feal-differential-cryptanalysis/ and loads when your prompt matches the skill's trigger.

Who uses this skill

The Feal Differential Cryptanalysis Claude Code skill is built for security engineers, penetration testers, DevSecOps practitioners, and development teams hardening codebases and infrastructure. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 187,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).

How to install

Free

Manual install (2 steps)

mkdir -p ~/.claude/skills/feal-differential-cryptanalysis
curl -L https://claudskills.com/skills/feal-differential-cryptanalysis/SKILL.md \
  -o ~/.claude/skills/feal-differential-cryptanalysis/SKILL.md

Or just download SKILL.md directly and drop it into ~/.claude/skills/feal-differential-cryptanalysis/. Claude Code auto-discovers it on next session.

Skills live at ~/.claude/skills/feal-differential-cryptanalysis/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\feal-differential-cryptanalysis\SKILL.md on Windows. See the full install guide for step-by-step instructions.

📱 Install from your phone or desktop Telegram

Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →

Pro

One-click install via the desktop app

The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.

Pro

For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.

See pricing → Download desktop app

Frequently asked questions

How do I install the Feal Differential Cryptanalysis Claude Code skill?

Install via the ClaudSkills desktop app (one click) or copy SKILL.md from the source repository to ~/.claude/skills/feal-differential-cryptanalysis/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.

What does the Feal Differential Cryptanalysis skill do?

Is this skill free to install?

Yes. ClaudSkills is an open registry — every skill keeps its source repository's license, and manual install via copy is free. ClaudSkills Pro ($9/mo, $79/yr, or $149 one-time) adds one-click install via the desktop app and a multi-signal Quality Score.

When should I use the Feal Differential Cryptanalysis skill?

Use Feal Differential Cryptanalysis when your Claude Code task falls under the Security category — specifically in the red team area. Claude Code auto-discovers installed skills and invokes the right one based on the task description, so you can also ask Claude directly (e.g. "use Feal Differential Cryptanalysis" or describe the task and let Claude pick). Browse related skills at /category/security/.

What is a Claude Code skill and how does the Feal Differential Cryptanalysis skill fit in?

A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. Feal Differential Cryptanalysis is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Security category. Learn more at /learn/what-is-a-claude-skill/.

Attribution & license

Cite this skill

If you reference this skill in a blog post, paper, or documentation, you can cite it as:

APA

oaustegard. (2026). Feal Differential Cryptanalysis [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/feal-differential-cryptanalysis/

BibTeX

@misc{feal-differential-cryptanalysis-2026,
  author    = {oaustegard},
  title     = {Feal Differential Cryptanalysis [Claude Code skill]},
  year      = {2026},
  publisher = {ClaudSkills},
  url       = {https://claudskills.com/skills/feal-differential-cryptanalysis/}
}

Embed this skill

Promote, attribute, or link this skill from your own README, blog post, or documentation. All three snippets are free to use — no sign-up, no API key. More distribution surfaces →

Badge

[![ClaudSkills](https://claudskills.com/badge/feal-differential-cryptanalysis.svg)](https://claudskills.com/skills/feal-differential-cryptanalysis/?utm_source=badge&utm_medium=readme&utm_campaign=skill_badge)

Security scan

Grade A · scanned 2026-08-18 — free static scan against the OWASP Agentic Skills Top 10.

No risk patterns were found in any of the ten OWASP-aligned categories. How grading works ›

✓ Prompt injection
✓ Data exfiltration
✓ Supply chain
✓ Reverse shell
✓ Credentials
✓ Execution
✓ Filesystem
✓ Persistence
✓ Obfuscation
✓ Network

Show this grade on your repo (click to copy):

[![Security: A](https://img.shields.io/badge/Security-A-2e7d32)](https://claudskills.com/skills/feal-differential-cryptanalysis/#security)

More Security skills

Browse all Security skills in the ClaudSkills registry, or explore these other picks from the same category:

Browse all Security skills → Top 100 skills

Part of ClaudSkills — the open registry for Claude Skills & Claude Code Skills. · What's New · Install guide · About · llms.txt

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