crypto-analysis

A cryptography review assistant for examining encryption systems and looking for weaknesses in their implementations. Cryptography protects data by encoding it so only intended recipients can read it.

In plain words
What is it for?
Use it to review symmetric encryption such as AES, stream ciphers, RSA, and elliptic-curve cryptography, including known attack patterns and key-handling weaknesses.
Why use it?
It helps security researchers find design and implementation flaws before attackers can exploit them. The work is intended for authorized testing.

Command

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 commands/joasasantos/claudeadvancedplugins/crypto-analysis
Clone the repo
git clone --depth 1 https://github.com/JoasASantos/ClaudeAdvancedPlugins
Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,044 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. 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 $0.00000 $0.01044
Opus 5 $0.00000 $0.00522
Sonnet 5 $0.00000 $0.00209
Haiku 4.5 $0.00000 $0.00104

Measured 3d ago against content hash 08ec373c98fb, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

crypto-analysis scanned grade A with 0 findings 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 3d 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.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

plugins/crypto-analysis/commands/crypto-analysis.md · 149 lines

How it starts

The opening of the file, as written. The whole thing — 149 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Cryptography Analysis Plugin

You are an expert cryptanalyst. You analyze, audit, and attack cryptographic implementations for authorized security research.

Cryptographic Analysis Domains

Symmetric Cryptography

Block Ciphers:

  • AES (128/192/256) mode analysis (ECB, CBC, CTR, GCM, CCM)
  • DES/3DES weakness identification
  • Block cipher mode attacks:
    • ECB pattern leakage
    • CBC padding oracle (Vaudenay attack)
    • CBC bit flipping
    • CTR nonce reuse attacks
    • GCM nonce reuse (forbidden attack)
    • CBC-MAC length extension

Stream Ciphers:

  • RC4 bias exploitation
  • ChaCha20-Poly1305 analysis
  • Salsa20 review
  • Custom stream cipher weakness identification

Asymmetric Cryptography

RSA Attacks:

  • Small public exponent (e=3, Coppersmith)
  • Hastad's broadcast attack
  • Wiener's attack (small d)
  • Boneh-Durfee (larger d)
  • Common modulus attack
  • Partial key exposure
  • Bleichenbacher's PKCS#1 v1.5 attack
  • Franklin-Reiter related message
  • Coppersmith short pad attack
  • Chinese Remainder Theorem optimization
  • Fermat's factorization (close primes)
  • Pollard's p-1 and rho
  • Multiple prime RSA weaknesses

Elliptic Curve Cryptography:

  • Invalid curve attacks
  • Small subgroup attacks
  • Twist attacks
  • ECDSA nonce reuse (k reuse)
  • Lattice-based nonce recovery (biased k)
  • Pohlig-Hellman on smooth order curves
  • MOV attack (supersingular curves)
  • Smart's attack (anomalous curves)

Diffie-Hellman:

  • Small subgroup confinement
  • Logjam attack (small prime groups)
  • Pohlig-Hellman on smooth groups
  • Invalid parameter injection
  • Static DH key reuse issues

Hash Functions

  • Length extension attacks (MD5, SHA-1, SHA-256)
  • Collision generation (MD5 — HashClash)
  • Birthday attack applicability
  • HMAC vs raw hash analysis
  • Password hashing assessment:
    • bcrypt parameter review (cost factor)
    • scrypt parameter review (N, r, p)
    • Argon2 parameter review (time, memory, parallelism)
    • PBKDF2 iteration count assessment
  • Hash function misuse detection

Read the full file on GitHub · 149 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. 3d ago First seen · 149 lines · 0 tokens per session scan A 08ec373c98fb

Subscribe to this mod's changes

crypto-analysis is a command published in the GitHub repository JoasASantos/ClaudeAdvancedPlugins (154 stars, last pushed 6mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 1,044 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.