wycheproof

wycheproof is a skill for Claude Code from marduk191/qwen3_mcp. It costs 28 tokens per session (4,645 once invoked), scanned A, a copy of wycheproof, MIT.

A collection of test vectors for checking cryptographic code against valid inputs, invalid inputs, edge cases, and known attack patterns. A test vector is a defined input and expected result used to verify an implementation.

In plain words
What is it for?
Use it to test implementations of cryptographic algorithms and constructions, including their handling of invalid data, key and parameter sizes, and known vulnerabilities.
Why use it?
Cryptographic code can fail on unusual inputs in ways that expose keys, enable forged signatures, or allow unintended decryption. These cases provide repeatable checks for such mistakes.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the testing-handbook-skills plugin — 15 skills shipped together

Good fit Use it to test implementations of cryptographic algorithms and constructions, including their handling of invalid data, key and parameter sizes, and known vulnerabilities.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/marduk191/qwen3_mcp/wycheproof
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.

Any agent
npx skills add marduk191/qwen3_mcp --skill wycheproof
Clone the repo
git clone --depth 1 https://github.com/marduk191/qwen3_mcp

Made for: Claude Code.

Or install testing-handbook-skills, the plugin that ships this one along with the rest of its 15 skills.

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 wycheproof

README.md
[![agentmods](https://agentmods.dev/badge/skills/marduk191/qwen3_mcp/wycheproof/github.svg)](https://agentmods.dev/skills/marduk191/qwen3_mcp/wycheproof)
Your own site
<a href="https://agentmods.dev/skills/marduk191/qwen3_mcp/wycheproof"><img src="https://agentmods.dev/badge/skills/marduk191/qwen3_mcp/wycheproof/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.

agentmods 80×15 button for wycheproof

Your own site · 80×15
<a href="https://agentmods.dev/skills/marduk191/qwen3_mcp/wycheproof"><img src="https://agentmods.dev/badge/skills/marduk191/qwen3_mcp/wycheproof.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 28 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,645 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.
Origin 94% copy Near-identical to another mod 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 $0.00028 $0.04645
Opus 5 $0.00014 $0.02322
Sonnet 5 $0.00006 $0.00929
Haiku 4.5 $0.00003 $0.00464

Measured 10d ago against content hash f545b71bd68a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

wycheproof 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 -o "${TMP_WYCHEPROOF_FOLDER}${i}" "${BASE_URL}${i}"
Origin

This is a copy

94% identical to wycheproof — 5 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/testing-handbook-skills/skills/wycheproof/SKILL.md · 534 lines

How it starts

The opening of the file, as written. The whole thing — 534 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Wycheproof

Wycheproof is an extensive collection of test vectors designed to verify the correctness of cryptographic implementations and test against known attacks. Originally developed by Google, it is now a community-managed project where contributors can add test vectors for specific cryptographic constructions.

Background

Key Concepts

Concept Description
Test vector Input/output pair for validating crypto implementation correctness
Test group Collection of test vectors sharing attributes (key size, IV size, curve)
Result flag Indicates if test should pass (valid), fail (invalid), or is acceptable
Edge case testing Testing for known vulnerabilities and attack patterns

Why This Matters

Cryptographic implementations are notoriously difficult to get right. Even small bugs can:

  • Expose private keys
  • Allow signature forgery
  • Enable message decryption
  • Create consensus problems when different implementations accept/reject the same inputs

Wycheproof has found vulnerabilities in major libraries including OpenJDK's SHA1withDSA, Bouncy Castle's ECDHC, and the elliptic npm package.

When to Use

Apply Wycheproof when:

  • Testing cryptographic implementations (AES-GCM, ECDSA, ECDH, RSA, etc.)
  • Validating that crypto code handles edge cases correctly
  • Verifying implementations against known attack vectors
  • Setting up CI/CD for cryptographic libraries
  • Auditing third-party crypto code for correctness

Consider alternatives when:

  • Testing for timing side-channels (use constant-time testing tools instead)
  • Finding new unknown bugs (use fuzzing instead)
  • Testing custom/experimental cryptographic algorithms (Wycheproof only covers established algorithms)

Quick Reference

Scenario Recommended Approach Notes
AES-GCM implementation Use aes_gcm_test.json 316 test vectors across 44 test groups
ECDSA verification Use ecdsa_*_test.json for specific curves Tests signature malleability, DER encoding
ECDH key exchange Use ecdh_*_test.json Tests invalid curve attacks
RSA signatures Use rsa_*_test.json Tests padding oracle attacks
ChaCha20-Poly1305 Use chacha20_poly1305_test.json Tests AEAD implementation

Read the full file on GitHub · 534 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. 10d ago First seen · 534 lines · 28 tokens per session scan A f545b71bd68a

Subscribe to this mod's changes

wycheproof is a skill published in the GitHub repository marduk191/qwen3_mcp (13 stars, last pushed 7mo ago), licensed MIT. It adds 28 tokens to every session and 4,645 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). It is 94% identical to wycheproof, differing in 5 lines, and is treated as a copy.

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