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.
npx skills add trilwu/secskills --skill reviewing-cryptographygit clone --depth 1 https://github.com/trilwu/secskillsWrote 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.
[](https://agentmods.dev/skills/trilwu/secskills/reviewing-cryptography)<a href="https://agentmods.dev/skills/trilwu/secskills/reviewing-cryptography"><img src="https://agentmods.dev/badge/skills/trilwu/secskills/reviewing-cryptography/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/trilwu/secskills/reviewing-cryptography"><img src="https://agentmods.dev/badge/skills/trilwu/secskills/reviewing-cryptography.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 1 finding, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium Excessive Agency · line 204 Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00070 | $0.02704 |
| Opus 5 | $0.00035 | $0.01352 |
| Sonnet 5 | $0.00014 | $0.00541 |
| Haiku 4.5 | $0.00007 | $0.00270 |
Grade A, and why
reviewing-cryptography 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 10d 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.
curl -sL "https://defuddle.md/<url>" # scheme in the path is optional Copies of this mod
1 near-identical copy found in the catalogue:
- reviewing-cryptography — 100% identical, 0 lines differ
How it starts
The opening of the file, as written. The whole thing — 249 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Reviewing Cryptography
Almost no real system is broken by cryptanalysis. They are broken by misuse: a reused nonce, unauthenticated ciphertext, a comparison that returns early, a key checked into git. Review for misuse, and leave primitive design to cryptographers.
When to Use
- Auditing code that encrypts, decrypts, signs, verifies, or hashes
- Reviewing key management, rotation, and storage
- Assessing TLS/mTLS configuration and certificate validation
- Reviewing JWT, session token, and API signature schemes
- Checking password and secret storage
- Evaluating randomness quality for security-relevant values
When NOT to Use
- Designing a new primitive or protocol — that needs a cryptographer and formal review, not a code audit
- Breaking cryptography in a CTF — different discipline; use
solving-oriented offensive skills and known-attack tooling - General code review — use
auditing-code-for-vulnerabilities - Password cracking — use
cracking-passwords
The Misuse Checklist
Work through these in order. Each has caught real production breaks.
1. Is the ciphertext authenticated?
Encryption without authentication is the single most common serious finding. CBC or CTR without a MAC means an attacker can modify plaintext — and with a decryption oracle, recover it (padding oracle).
Good: AES-GCM, ChaCha20-Poly1305, AES-CBC + HMAC (encrypt-then-MAC)
Bad: AES-CBC alone, AES-ECB (ever), CTR without a MAC, MAC-then-encrypt
rg -n 'AES/ECB|AES\.MODE_ECB|CipherMode\.ECB|"AES"\)' -i
rg -n 'AES/CBC/PKCS5Padding|MODE_CBC|createCipheriv\(.*cbc' -i
If you see CBC, find the MAC. If there is no MAC, that is a finding regardless of how the ciphertext is transported.
2. Nonce and IV handling
| Mode | Rule | Failure |
|---|---|---|
| GCM / ChaCha20-Poly1305 | Never reuse a (key, nonce) pair | Catastrophic: reveals the auth key, forgery becomes trivial |
| CBC | IV must be unpredictable and random per message | Chosen-plaintext attacks (BEAST-class) |
| CTR | Never reuse a counter with the same key | Keystream reuse; XOR of plaintexts |
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.
- 10d ago First seen · 249 lines · 70 tokens per session scan A 223587ea2425
reviewing-cryptography is a skill published in the GitHub repository trilwu/secskills (138 stars, last pushed 5d ago), licensed MIT. It adds 70 tokens to every session and 2,704 once invoked, about $0.0003 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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