MysterionRiseMysterionRise/ctf-kit/skills/crypto/SKILL.md

crypto

Skill12 starsChanged 9 months agoMITView on GitHub

Solve CTF cryptography challenges including encryption, hashing, and encoding. Use when you see: Base64 (trailing ==), hex strings (32/40/64 chars for MD5/SHA1/SHA256), RSA parameters (n=, e=, c=, p=, q=), XOR-encrypted data, .pem .key .enc files, classical ciphers (Caesar, Vigenere, substitution), encoding chains, or "crack this hash". Tools: xortool, hashid, hashcat, john, RsaCtfTool, openssl.

6 other projects use a version of this.

Adopted by

Most recently taken up by

zapek/Xerestheir own version, first seen Oct 8, 2026
QuantConnect/Documentationtheir own version, first seen Oct 8, 2026
emre-guler/websectheir own version, first seen Aug 27, 2026
Shad0wMazt3r/The-Scaffoldingtheir own version, first seen Apr 24, 2026
zubair-trabzada/ai-crypto-claudetheir own version, first seen Apr 16, 2026
Rayan55050/progressive-agenttheir own version, first seen Feb 24, 2026

Other versions6 projects use a version of this.
Word for word · 0
None found.
Edited · 0
None found.
Wrote their own version · 6
QuantConnect/Documentation★ 268same name
zapek/Xeres★ 223same name
zubair-trabzada/ai-crypto-claude★ 47same name
Shad0wMazt3r/The-Scaffolding★ 3same name
emre-guler/websec★ 2same name
Rayan55050/progressive-agent★ 2same name
How matches are found. Word for word: the exact same text. Edited: shares passages with this file (“99% same” means 99% of its five-word phrases also appear here; 10% or more counts). Their own version: similar meaning, or, weakest, the same name. We can’t tell which project had it first. Projects are counted among the 200 most-starred candidates, and mentions are links to the repository we found, up to 50 per site, so both counts are a floor.
In this repository15 other files it gives its agents.
- AGENTS.mdAGENTS.md
- CLAUDE.mdCLAUDE.md
- analyzeSkill
- competeSkill
- flagSkill
- forensicsSkill
- hereSkill
- miscSkill
- osintSkill
- pwnSkill
- reverseSkill
- statusSkill
- stegoSkill
- team-solveSkill
- webSkill

The file

We split this skill into the rules it gives an agent

4 rules. 0 are common, 2 are distinctive, and 2 are very specific to this project.

0
Common
Most of the 4 edited versions we read keep these.
2
Distinctive
This author's own choices. Worth a look.
2
Very specific
Tied to their project's names, files or tools. Probably skip.

Common
Distinctive
Very specific

Distinctive:
Use this command for challenges involving:
line 18
Distinctive:
Run the crypto analysis:
line 37
Very specific:
All scripts produce a === PARSED RESULTS (JSON) === section.
line 88
Very specific:
When using /ctf-kit:team-solve with a crypto challenge, the lead spawns 3 specialists:
line 92

“Common” is measured: kept by at least 6 in 10 of the 4 edited versions of this file we could read. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.

Keep what fits and drop the rest. Your version, ready for your agents.

Files

SKILL.md

CTF Crypto

Analyze and solve cryptography challenges.

When to Use

Use this command for challenges involving:

Encrypted text or files
Hash cracking
RSA/asymmetric cryptography
XOR encryption
Classical ciphers (Caesar, Vigenere, etc.)
Encoding chains (Base64, hex, etc.)

Bundled Scripts

check-tools.sh — Verify required crypto tools are installed
run-xortool.sh — Analyze XOR-encrypted files with key length detection. Outputs JSON with key lengths, probabilities, and cracking suggestions.
identify-hash.sh — Identify hash types from strings or files. Outputs JSON with hash type, hashcat mode numbers, and john format names.

Instructions

First check tool availability: bash scripts/check-tools.sh
Run the crypto analysis:
```
ctf run crypto $ARGUMENTS
```
For hash identification (outputs structured JSON with cracking commands):
```
bash scripts/identify-hash.sh <hash-string>
bash scripts/identify-hash.sh hashes.txt
```
The JSON output includes:
- hashes[].types[]: identified hash types with confidence
- hashes[].types[].hashcat_mode: exact hashcat -m number
- hashes[].types[].jtr_format: exact john --format value
- suggestions: ready-to-run cracking commands
For XOR analysis (outputs structured JSON with key candidates):
```
bash scripts/run-xortool.sh <encrypted-file>
bash scripts/run-xortool.sh <file> 8        # known key length
bash scripts/run-xortool.sh <file> 8 20     # key length + most frequent char (space=0x20)
```
The JSON output includes:
- key_lengths[]: candidates with probability percentages
- best_key_length: most probable key length
- key_found: actual key if detected
- decrypted_files: paths to decrypted candidates
Based on JSON findings, chain to next tool:
- Hash identified → run hashcat/john with the exact mode from JSON
- XOR key found → decrypt with xortool-xor -n -s '<key>' <file>
- RSA parameters → run RsaCtfTool -n <n> -e <e> --uncipher <c>

Common Patterns

Pattern	Likely Type
32 hex chars	MD5 hash
40 hex chars	SHA1 hash
64 hex chars	SHA256 hash
`==` at end	Base64
All caps + 2-7	Base32
n=..., e=...	RSA parameters

Output Format

All scripts produce a === PARSED RESULTS (JSON) === section. Use the suggestions array for ready-to-run next commands.

Team Roles

When using /ctf-kit:team-solve with a crypto challenge, the lead spawns 3 specialists:

Role	Teammate Name	Focus	Tools	First Action
Classical & Encoding	`classical-analyst`	Frequency analysis, substitution ciphers, Vigenere, transposition, encoding chains (Base64/hex/ROT13)	CyberChef, `scripts/run-decode.sh`, `scripts/identify-hash.sh`, dcode.fr	Run decode + hash-id on all files, check for known cipher patterns
Asymmetric & Math	`rsa-specialist`	RSA factoring (small primes, Fermat, Wiener), padding oracles, Boneh-Durfee, ECC, Diffie-Hellman	RsaCtfTool, openssl, sage, python3	Extract RSA parameters (n,e,c), try RsaCtfTool, check factordb
Symmetric & Hash	`symmetric-cracker`	XOR key recovery, AES mode attacks (ECB/CBC), hash cracking, HMAC	xortool, hashcat, john, `scripts/run-xortool.sh`	Run xortool on binary files, identify and crack any hashes

When to broadcast

Classical: "Identified cipher type as Vigenere with key length N" — RSA specialist can ignore
RSA: "Found factors of n" or "Need ciphertext in different format" — others adjust
Symmetric: "XOR key found: KEY" — others try decrypting their findings with it
Any: "Found the flag" — immediate broadcast, all stop

Example Usage

/ctf-kit:crypto cipher.txt
/ctf-kit:crypto encrypted.bin
/ctf-kit:crypto ./challenge/

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