sc-crypto

sc-crypto is a skill for Claude Code, Codex from ersinkoc/security-check. It costs 27 tokens per session (1,117 once invoked), scanned A, original, MIT.

A security check for mistakes in encryption and related cryptographic code. It looks for weak algorithms, unsafe cipher settings, predictable randomness, poor key handling, and disabled certificate checks.

In plain words
What is it for?
Use it to review encryption, random-number generation, key handling, and TLS/SSL configuration for common security mistakes.
Why use it?
It helps identify code that may appear encrypted but can be weakened or bypassed because of unsafe implementation choices.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/ersinkoc/security-check/sc-crypto
Any agent
npx skills add ersinkoc/security-check --skill sc-crypto
Clone the repo
git clone --depth 1 https://github.com/ersinkoc/security-check

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for sc-crypto

README.md
[![agentmods](https://agentmods.dev/badge/skills/ersinkoc/security-check/sc-crypto.svg)](https://agentmods.dev/skills/ersinkoc/security-check/sc-crypto)
Your own site
<a href="https://agentmods.dev/skills/ersinkoc/security-check/sc-crypto"><img src="https://agentmods.dev/badge/skills/ersinkoc/security-check/sc-crypto.svg" alt="Measured on agentmods" height="20"></a>
Per session 27 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,117 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00027 $0.01117
Opus 5 $0.00014 $0.00558
Sonnet 5 $0.00005 $0.00223
Haiku 4.5 $0.00003 $0.00112

Measured 6d ago against content hash 341903dbf000, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

sc-crypto scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

requests.get(url, verify=False)
skills/sc-crypto/SKILL.md · 130 lines

How it starts

The opening of the file, as written. The whole thing — 130 lines — stays where its author put it; the contents beside it link to each section on GitHub.

SC: Cryptography Misuse

Purpose

Detects cryptographic implementation errors including use of weak algorithms (MD5, SHA1 for security), insecure cipher modes (ECB), static or hardcoded initialization vectors, missing authentication (AES-CBC without HMAC), weak pseudo-random number generators for security purposes, insufficient key lengths, and disabled certificate validation.

Activation

Called by sc-orchestrator during Phase 2. Always runs.

Phase 1: Discovery

Keyword Patterns to Search

# Weak algorithms
"MD5", "md5", "SHA1", "sha1", "DES", "3DES", "RC4", "RC2",
"Blowfish", "IDEA"

# Cipher modes
"ECB", "CBC", "AES/ECB", "AES/CBC", "Mode.ECB"

# Initialization vectors
"iv =", "IV =", "nonce =", "static.*iv", "hardcoded.*iv",
"bytes(16)", "b'\\x00' * 16"

# Weak PRNG
"Math.random(", "random.random(", "random.randint(",
"rand()", "srand(", "java.util.Random", "System.Random"

# Key management
"key =", "encryption_key", "secret_key",
"AES.new(", "Cipher.getInstance(", "crypto.createCipheriv("

# TLS/SSL
"verify=False", "verify_ssl=False", "rejectUnauthorized: false",
"InsecureSkipVerify", "TLSv1", "SSLv3",
"CERT_NONE", "CERT_OPTIONAL"

Vulnerability Patterns

1. Weak Hash for Security:

# VULNERABLE: MD5 for password hashing
password_hash = hashlib.md5(password.encode()).hexdigest()

# VULNERABLE: SHA1 for signature verification
signature = hashlib.sha1(data.encode()).hexdigest()

# SAFE: SHA-256+ for signatures, bcrypt/argon2 for passwords
password_hash = bcrypt.hashpw(password.encode(), bcrypt.gensalt())
signature = hashlib.sha256(data.encode()).hexdigest()

2. ECB Mode:

// VULNERABLE: ECB mode reveals patterns in encrypted data
Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");

// SAFE: GCM mode (authenticated encryption)
Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");

3. Static IV:

// VULNERABLE: Hardcoded IV
const iv = Buffer.from('0000000000000000');
const cipher = crypto.createCipheriv('aes-256-cbc', key, iv);

// SAFE: Random IV per encryption
const iv = crypto.randomBytes(16);
const cipher = crypto.createCipheriv('aes-256-cbc', key, iv);

Read the full file on GitHub · 130 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 6d ago First seen · 130 lines · 27 tokens per session scan A 341903dbf000

Subscribe to this mod's changes

sc-crypto is a skill published in the GitHub repository ersinkoc/security-check (56 stars, last pushed 2mo ago), licensed MIT. It adds 27 tokens to every session and 1,117 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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