crypto-analysis

Breaks cryptographic systems and decrypts ciphertext. Use when working with RSA, AES, XOR, classical ciphers, hash functions, or when challenge involves encryption, decryption, keys, or mathematical crypto attacks.

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Forks 31

Install this agent skill to your Project

npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/devops/crypto-analysis-kiwamizamurai-cctf-ad622414

SKILL.md

Crypto Analysis Skill

Quick Workflow

Progress:
- [ ] Try Ciphey auto-decrypt first
- [ ] Identify crypto type (RSA/AES/XOR/classical)
- [ ] Check for known weaknesses
- [ ] Implement attack
- [ ] Decrypt flag

Step 1: Auto-Decrypt (Try First!)

bash

ciphey -t "ENCODED_TEXT"    # Auto-detects and decrypts
ciphey -f encrypted.txt     # From file

Step 2: Identify Crypto Type

Pattern	Crypto Type	Reference
`n, e, c` variables	RSA	reference/rsa-attacks.md
16/32 byte key, IV	AES	reference/aes-attacks.md
XOR operations	XOR/Stream	reference/classical.md
Polynomial mod	Lattice	reference/lattice.md

RSA Attack Decision Tree

├── e small (≤5)?     → Direct eth root
├── e very large?     → Wiener's Attack
├── Multiple n,e,c?   → Hastad's Broadcast
├── Same n, diff e?   → Common Modulus
├── GCD(n1,n2) > 1?   → Common Factor
├── p ≈ q?            → Fermat Factorization
├── dp/dq leaked?     → Partial Key Recovery
└── Default           → FactorDB / yafu

Full implementations: reference/rsa-attacks.md

Quick Commands