Official agent skill

Wycheproof

by trailofbits in trailofbits/skills

Validates cryptographic implementations against Project Wycheproof's test vectors, which encode known attacks and edge cases across AES, RSA, ECDSA, ECDH, and more.

OfficialCC-BY-SA-4.0Auto-check passedSecurity

Install Wycheproof

skills CLI
$ npx skills add trailofbits/skills --skill wycheproof -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install trailofbits/skills wycheproof --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/trailofbits/skills.git skills-src && mkdir -p .claude/skills && cp -r skills-src/plugins/testing-handbook-skills/skills/wycheproof .claude/skills/wycheproof && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
wycheproof
GitHub stars
7.4k
Token cost
~4.9k tokens
SKILL.md length
1,410 words
Files
3 (incl. assets)
Skills in repo
79
Repo updated
First seen
Licence
CC-BY-SA-4.0

At a glance

Validates cryptographic implementations against Project Wycheproof's test vectors, which encode known attacks and edge cases across AES, RSA, ECDSA, ECDH, and more.

  • Works in 4 steps: Add Wycheproof to Your Project → Parse Test Vectors → Write Testing Harness → …
  • Testing a crypto implementation against known attacks
  • SKILL.md covers Background, When to Use, Quick Reference and Testing Workflow, plus 8 more sections
  • Calls git and curl; reaches github.com and raw.githubusercontent.com

What it does

Wycheproof is an agent skill from trailofbits/skills, published by the product's own GitHub organization. Validates cryptographic implementations against Project Wycheproof's test vectors, which encode known attacks and edge cases across AES, RSA, ECDSA, ECDH, and more. Covers loading test vectors, mapping result flags onto pass and fail expectations, and reading a failure. Use when testing a crypto implementation against known attacks, checking a library against standard test vectors, or investigating why two implementations disagree on the same input.

Its SKILL.md is about 4.9k tokens, which your agent loads only when the skill is triggered. The skill folder holds 4 other files, including assets (for example `agents/openai.yaml`).

It sits in Security, covering Cryptography. The repository describes itself as: Trail of Bits Claude Code skills for security research, vulnerability detection, and audit workflows. The licence is CC-BY-SA-4.0.

When your agent uses it

  • Testing a crypto implementation against known attacks
  • Checking a library against standard test vectors
  • Investigating why two implementations disagree on the same input

Example prompts

  • “Use the wycheproof skill to validate cryptographic implementations against Project Wycheproof's test vectors, which encode known attacks and edge…”
  • “/wycheproof”

Requirements

  • Python 3

Workflow steps

4 steps, taken from the step headings in SKILL.md.

  1. Add Wycheproof to Your Project
  2. Parse Test Vectors
  3. Write Testing Harness
  4. CI Integration

What it can do on your machine

Read from SKILL.md and the folder at commit 82fe822. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Shell commands in SKILL.md call:

    • git
    • curl

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    Hosts in commands or code, which the agent is likely to contact:

    • github.com
    • raw.githubusercontent.com

    Also links to:

    • npmjs.com
    • pypi.org
    • c2sp.org

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Wycheproof loads about 4.9k tokens when it runs. Until then it costs about 116 tokens; SKILL.md has 1,410 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~116
When it runs · the whole SKILL.md, loaded when a task matches
~4.9k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from trailofbits/skills at commit 82fe822, republished under its CC-BY-SA-4.0 licence (© trailofbits). 1,410 words, ~4,911 tokens.

Download SKILL.mdSave it as .claude/skills/wycheproof/SKILL.md (or your agent's skills folder). This skill also uses 2 other files; get the full folder from GitHub.
name
wycheproof
description
Validates cryptographic implementations against Project Wycheproof's test vectors, which encode known attacks and edge cases across AES, RSA, ECDSA, ECDH, and more. Covers loading test vectors, mapping result flags onto pass and fail expectations, and reading a failure. Use when testing a crypto implementation against known attacks, checking a library against standard test vectors, or investigating why two implementations disagree on the same input.
type
domain

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
ConceptDescription
Test vectorInput/output pair for validating crypto implementation correctness
Test groupCollection of test vectors sharing attributes (key size, IV size, curve)
Result flagIndicates if test should pass (valid), fail (invalid), or is acceptable
Edge case testingTesting 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

ScenarioRecommended ApproachNotes
AES-GCM implementationUse aes_gcm_test.json316 test vectors across 44 test groups
ECDSA verificationUse ecdsa_*_test.json for specific curvesTests signature malleability, DER encoding
ECDH key exchangeUse ecdh_*_test.jsonTests invalid curve attacks
RSA signaturesUse rsa_*_test.jsonTests padding oracle attacks
ChaCha20-Poly1305Use chacha20_poly1305_test.jsonTests AEAD implementation

Testing Workflow

Phase 1: Setup                 Phase 2: Parse Test Vectors
┌─────────────────┐          ┌─────────────────┐
│ Add Wycheproof  │    →     │ Load JSON file  │
│ as submodule    │          │ Filter by params│
└─────────────────┘          └─────────────────┘
         ↓                            ↓
Phase 4: CI Integration        Phase 3: Write Harness
┌─────────────────┐          ┌─────────────────┐
│ Auto-update     │    ←     │ Test valid &    │
│ test vectors    │          │ invalid cases   │
└─────────────────┘          └─────────────────┘

Repository Structure

The Wycheproof repository is organized as follows:

text
┣ 📜 README.md       : Project overview
┣ 📂 doc             : Documentation
┣ 📂 java            : Java JCE interface testing harness
┣ 📂 javascript      : JavaScript testing harness
┣ 📂 schemas         : Test vector schemas
┣ 📂 testvectors     : Test vectors
┗ 📂 testvectors_v1  : Updated test vectors (more detailed)

The essential folders are testvectors and testvectors_v1. While both contain similar files, testvectors_v1 includes more detailed information and is recommended for new integrations.

Supported Algorithms

Wycheproof provides test vectors for a wide range of cryptographic algorithms:

CategoryAlgorithms
Symmetric EncryptionAES-GCM, AES-EAX, ChaCha20-Poly1305
SignaturesECDSA, EdDSA, RSA-PSS, RSA-PKCS1
Key ExchangeECDH, X25519, X448
HashingHMAC, HKDF
Curvessecp256k1, secp256r1, secp384r1, secp521r1, ed25519, ed448

Test File Structure

Each JSON test file tests a specific cryptographic construction. All test files share common attributes:

json
"algorithm"         : The name of the algorithm tested
"schema"            : The JSON schema (found in schemas folder)
"generatorVersion"  : The version number
"numberOfTests"     : The total number of test vectors in this file
"header"            : Detailed description of test vectors
"notes"             : In-depth explanation of flags in test vectors
"testGroups"        : Array of one or multiple test groups
Test Groups

Test groups group sets of tests based on shared attributes such as:

  • Key sizes
  • IV sizes
  • Public keys
  • Curves

This classification allows extracting tests that meet specific criteria relevant to the construction being tested.

Test Vector Attributes
Shared Attributes

All test vectors contain four common fields:

  • tcId: Unique identifier for the test vector within a file
  • comment: Additional information about the test case
  • flags: Descriptions of specific test case types and potential dangers (referenced in notes field)
  • result: Expected outcome of the test

The result field can take three values:

ResultMeaning
validTest case should succeed
acceptableTest case is allowed to succeed but contains non-ideal attributes
invalidTest case should fail
Unique Attributes

Unique attributes are specific to the algorithm being tested:

AlgorithmUnique Attributes
AES-GCMkey, iv, aad, msg, ct, tag
ECDH secp256k1public, private, shared
ECDSAmsg, sig, result
EdDSAmsg, sig, pk

Implementation Guide

Phase 1: Add Wycheproof to Your Project

Option 1: Git Submodule (Recommended)

Adding Wycheproof as a git submodule ensures automatic updates:

bash
git submodule add https://github.com/C2SP/wycheproof.git

Option 2: Fetch Specific Test Vectors

If submodules aren't possible, fetch specific JSON files:

bash
#!/bin/bash

TMP_WYCHEPROOF_FOLDER=".wycheproof/"
TEST_VECTORS=('aes_gcm_test.json' 'aes_eax_test.json')
BASE_URL="https://raw.githubusercontent.com/C2SP/wycheproof/master/testvectors_v1/"

# Create wycheproof folder
mkdir -p $TMP_WYCHEPROOF_FOLDER

# Request all test vector files if they don't exist
for i in "${TEST_VECTORS[@]}"; do
  if [ ! -f "${TMP_WYCHEPROOF_FOLDER}${i}" ]; then
    curl -o "${TMP_WYCHEPROOF_FOLDER}${i}" "${BASE_URL}${i}"
    if [ $? -ne 0 ]; then
      echo "Failed to download ${i}"
      exit 1
    fi
  fi
done
Phase 2: Parse Test Vectors

Identify the test file for your algorithm and parse the JSON:

Python Example:

python
import json

def load_wycheproof_test_vectors(path: str):
    testVectors = []
    try:
        with open(path, "r") as f:
            wycheproof_json = json.loads(f.read())
    except FileNotFoundError:
        print(f"No Wycheproof file found at: {path}")
        return testVectors

    # Attributes that need hex-to-bytes conversion
    convert_attr = {"key", "aad", "iv", "msg", "ct", "tag"}

    for testGroup in wycheproof_json["testGroups"]:
        # Filter test groups based on implementation constraints
        if testGroup["ivSize"] < 64 or testGroup["ivSize"] > 1024:
            continue

        for tv in testGroup["tests"]:
            # Convert hex strings to bytes
            for attr in convert_attr:
                if attr in tv:
                    tv[attr] = bytes.fromhex(tv[attr])
            testVectors.append(tv)

    return testVectors

JavaScript Example:

javascript
const fs = require('fs').promises;

async function loadWycheproofTestVectors(path) {
  const tests = [];

  try {
    const fileContent = await fs.readFile(path);
    const data = JSON.parse(fileContent.toString());

    data.testGroups.forEach(testGroup => {
      testGroup.tests.forEach(test => {
        // Add shared test group properties to each test
        test['pk'] = testGroup.publicKey.pk;
        tests.push(test);
      });
    });
  } catch (err) {
    console.error('Error reading or parsing file:', err);
    throw err;
  }

  return tests;
}
Phase 3: Write Testing Harness

Create test functions that handle both valid and invalid test cases.

Python/pytest Example:

python
import pytest
from cryptography.hazmat.primitives.ciphers.aead import AESGCM

tvs = load_wycheproof_test_vectors("wycheproof/testvectors_v1/aes_gcm_test.json")

@pytest.mark.parametrize("tv", tvs, ids=[str(tv['tcId']) for tv in tvs])
def test_encryption(tv):
    try:
        aesgcm = AESGCM(tv['key'])
        ct = aesgcm.encrypt(tv['iv'], tv['msg'], tv['aad'])
    except ValueError as e:
        # Implementation raised error - verify test was expected to fail
        assert tv['result'] != 'valid', tv['comment']
        return

    if tv['result'] == 'valid':
        assert ct[:-16] == tv['ct'], f"Ciphertext mismatch: {tv['comment']}"
        assert ct[-16:] == tv['tag'], f"Tag mismatch: {tv['comment']}"
    elif tv['result'] == 'invalid' or tv['result'] == 'acceptable':
        assert ct[:-16] != tv['ct'] or ct[-16:] != tv['tag']

@pytest.mark.parametrize("tv", tvs, ids=[str(tv['tcId']) for tv in tvs])
def test_decryption(tv):
    try:
        aesgcm = AESGCM(tv['key'])
        decrypted_msg = aesgcm.decrypt(tv['iv'], tv['ct'] + tv['tag'], tv['aad'])
    except ValueError:
        assert tv['result'] != 'valid', tv['comment']
        return
    except InvalidTag:
        assert tv['result'] != 'valid', tv['comment']
        assert 'ModifiedTag' in tv['flags'], f"Expected 'ModifiedTag' flag: {tv['comment']}"
        return

    assert tv['result'] == 'valid', f"No invalid test case should pass: {tv['comment']}"
    assert decrypted_msg == tv['msg'], f"Decryption mismatch: {tv['comment']}"

JavaScript/Mocha Example:

javascript
const assert = require('assert');

function testFactory(tcId, tests) {
  it(`[${tcId + 1}] ${tests[tcId].comment}`, function () {
    const test = tests[tcId];
    const ed25519 = new eddsa('ed25519');
    const key = ed25519.keyFromPublic(toArray(test.pk, 'hex'));

    let sig;
    if (test.result === 'valid') {
      sig = key.verify(test.msg, test.sig);
      assert.equal(sig, true, `[${test.tcId}] ${test.comment}`);
    } else if (test.result === 'invalid') {
      try {
        sig = key.verify(test.msg, test.sig);
      } catch (err) {
        // Point could not be decoded
        sig = false;
      }
      assert.equal(sig, false, `[${test.tcId}] ${test.comment}`);
    }
  });
}

// Generate tests for all test vectors
for (var tcId = 0; tcId < tests.length; tcId++) {
  testFactory(tcId, tests);
}
Phase 4: CI Integration

Ensure test vectors stay up to date by:

  1. Using git submodules: Update submodule in CI before running tests
  2. Fetching latest vectors: Run fetch script before test execution
  3. Scheduled updates: Set up weekly/monthly updates to catch new test vectors

Common Vulnerabilities Detected

Wycheproof test vectors are designed to catch specific vulnerability patterns:

VulnerabilityDescriptionAffected AlgorithmsExample CVE
Signature malleabilityMultiple valid signatures for same messageECDSA, EdDSACVE-2024-42459
Invalid DER encodingAccepting non-canonical DER signaturesECDSACVE-2024-42460, CVE-2024-42461
Invalid curve attacksECDH with invalid curve pointsECDHCommon in many libraries
Padding oracleTiming leaks in padding validationRSA-PKCS1Historical OpenSSL issues
Tag forgeryAccepting modified authentication tagsAES-GCM, ChaCha20-Poly1305Various implementations
Signature Malleability: Deep Dive

Problem: Implementations that don't validate signature encoding can accept multiple valid signatures for the same message.

Example (EdDSA): Appending or removing zeros from signature:

text
Valid signature:   ...6a5c51eb6f946b30d
Invalid signature: ...6a5c51eb6f946b30d0000  (should be rejected)

How to detect:

python
# Add signature length check
if len(sig) != 128:  # EdDSA signatures must be exactly 64 bytes (128 hex chars)
    return False

Impact: Can lead to consensus problems when different implementations accept/reject the same signatures.

Related Wycheproof tests:

  • EdDSA: tcId 37 - "removing 0 byte from signature"
  • ECDSA: tcId 06 - "Legacy: ASN encoding of r misses leading 0"

Case Study: Elliptic npm Package

This case study demonstrates how Wycheproof found three CVEs in the popular elliptic npm package (3000+ dependents, millions of weekly downloads).

Overview

The elliptic library is an elliptic-curve cryptography library written in JavaScript, supporting ECDH, ECDSA, and EdDSA. Using Wycheproof test vectors on version 6.5.6 revealed multiple vulnerabilities:

  • CVE-2024-42459: EdDSA signature malleability (appending/removing zeros)
  • CVE-2024-42460: ECDSA DER encoding - invalid bit placement
  • CVE-2024-42461: ECDSA DER encoding - leading zero in length field
Show full SKILL.md (568 more words)Show less
Methodology
  1. Identify supported curves: ed25519 for EdDSA
  2. Find test vectors: testvectors_v1/ed25519_test.json
  3. Parse test vectors: Load JSON and extract tests
  4. Write test harness: Create parameterized tests
  5. Run tests: Identify failures
  6. Analyze root causes: Examine implementation code
  7. Propose fixes: Add validation checks
Key Findings

EdDSA Issue (CVE-2024-42459):

  • Missing signature length validation
  • Allowed trailing zeros in signatures
  • Fix: Add if(sig.length !== 128) return false;

ECDSA Issue 1 (CVE-2024-42460):

  • Missing check for first bit being zero in DER-encoded r and s values
  • Fix: Add if ((data[p.place] & 128) !== 0) return false;

ECDSA Issue 2 (CVE-2024-42461):

  • DER length field accepted leading zeros
  • Fix: Add if(buf[p.place] === 0x00) return false;
Impact

All three vulnerabilities allowed multiple valid signatures for a single message, leading to consensus problems across implementations.

Lessons learned:

  • Wycheproof catches subtle encoding bugs
  • Reusable test harnesses pay dividends
  • Test vector comments and flags help diagnose issues
  • Even popular libraries benefit from systematic test vector validation

Advanced Usage

Tips and Tricks
TipWhy It Helps
Filter test groups by parametersFocus on test vectors relevant to your implementation constraints
Use test vector flagsUnderstand specific vulnerability patterns being tested
Check the notes fieldGet detailed explanations of flag meanings
Test both encrypt/decrypt and sign/verifyEnsure bidirectional correctness
Run tests in CICatch regressions and benefit from new test vectors
Use parameterized testsGet clear failure messages with tcId and comment
Common Mistakes
MistakeWhy It's WrongCorrect Approach
Only testing valid casesMisses vulnerabilities where invalid inputs are acceptedTest all result types: valid, invalid, acceptable
Ignoring "acceptable" resultImplementation might have subtle bugsTreat acceptable as warnings worth investigating
Not filtering test groupsWastes time on unsupported parametersFilter by keySize, ivSize, etc. based on your implementation
Not updating test vectorsMiss new vulnerability patternsUse submodules or scheduled fetches
Testing only one directionEncrypt/sign might work but decrypt/verify failsTest both operations
Tool Skills
SkillPrimary Use in Wycheproof Testing
pytestPython testing framework for parameterized tests
mochaJavaScript testing framework for test generation
constant-time-testingComplement Wycheproof with timing side-channel testing
cryptofuzzFuzz-based crypto testing to find additional bugs
Technique Skills
SkillWhen to Apply
coverage-analysisEnsure test vectors cover all code paths in crypto implementation
property-based-testingTest mathematical properties (e.g., encrypt/decrypt round-trip)
fuzz-harness-writingCreate harnesses for crypto parsers (complements Wycheproof)
SkillRelationship
crypto-testingWycheproof is a key tool in comprehensive crypto testing methodology
fuzzingUse fuzzing to find bugs Wycheproof doesn't cover (new edge cases)

Skill Dependency Map

                    ┌─────────────────────┐
                    │    wycheproof       │
                    │   (this skill)      │
                    └──────────┬──────────┘
                               │
           ┌───────────────────┼───────────────────┐
           │                   │                   │
           ▼                   ▼                   ▼
┌─────────────────┐ ┌─────────────────┐ ┌─────────────────┐
│  pytest/mocha   │ │ constant-time   │ │   cryptofuzz    │
│ (test framework)│ │   testing       │ │   (fuzzing)     │
└────────┬────────┘ └────────┬────────┘ └────────┬────────┘
         │                   │                   │
         └───────────────────┼───────────────────┘
                             │
                             ▼
              ┌──────────────────────────┐
              │   Technique Skills       │
              │ coverage, harness, PBT   │
              └──────────────────────────┘

Resources

Official Repository

Wycheproof GitHub Repository

The official repository contains:

  • All test vectors in testvectors/ and testvectors_v1/
  • JSON schemas in schemas/
  • Reference implementations in Java and JavaScript
  • Documentation in doc/
Real-World Examples

pycryptodome

The pycryptodome library integrates Wycheproof test vectors in their test suite, demonstrating best practices for Python crypto implementations.

Community Resources
  • C2SP Community - Cryptographic specifications and standards community maintaining Wycheproof
  • Wycheproof issues tracker - Report bugs in test vectors or suggest new constructions

Summary

Wycheproof is an essential tool for validating cryptographic implementations against known attack vectors and edge cases. By integrating Wycheproof test vectors into your testing workflow:

  1. Catch subtle encoding and validation bugs
  2. Prevent signature malleability issues
  3. Ensure consistent behavior across implementations
  4. Benefit from community-contributed test vectors
  5. Protect against known cryptographic vulnerabilities

The investment in writing a reusable testing harness pays dividends through continuous validation as new test vectors are added to the Wycheproof repository.

© trailofbits, CC-BY-SA-4.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 2 other files (assets) in plugins/testing-handbook-skills/skills/wycheproof of trailofbits/skills.

  • SKILL.md
  • agents/openai.yaml
  • assets/trail-of-bits-mark.svg

Open the folder on GitHubat commit 82fe822

Compare with similar skills

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    trailofbits/skills

    Official

    Searches and extracts data from Burp Suite project files on the command line: regex searches over responses, audit findings, proxy history and site map data.

    7.4k GitHub starsUsed in 3 repos~4.2k tokens
    Auto-check: notes

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Questions about Wycheproof

What does Wycheproof do?

Validates cryptographic implementations against Project Wycheproof's test vectors, which encode known attacks and edge cases across AES, RSA, ECDSA, ECDH, and more. Wycheproof is an agent skill from trailofbits/skills, published by the product's own GitHub organization. Validates cryptographic implementations against Project Wycheproof's test vectors, which encode known attacks and edge cases across AES, RSA, ECDSA, ECDH, and more.

When should I use Wycheproof?

Wycheproof fits situations like: testing a crypto implementation against known attacks; checking a library against standard test vectors; investigating why two implementations disagree on the same input.

How do I install Wycheproof in Claude Code?

Run `npx skills add trailofbits/skills --skill wycheproof -a claude-code`. Or copy the skill folder (plugins/testing-handbook-skills/skills/wycheproof in trailofbits/skills) into .claude/skills/wycheproof in your project. Claude Code loads it when a task matches its description.

How do I install Wycheproof in Codex?

Run `npx skills add trailofbits/skills --skill wycheproof -a codex`. Or copy the skill folder (plugins/testing-handbook-skills/skills/wycheproof in trailofbits/skills) into .agents/skills/wycheproof in your project. Codex loads it when a task matches its description.

Can I use Wycheproof in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add trailofbits/skills --skill wycheproof -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/wycheproof, .gemini/skills/wycheproof, .github/skills/wycheproof and .opencode/skills/wycheproof in your project.

What does Wycheproof need to run?

Going by SKILL.md and its folder, Wycheproof needs the command-line tools its instructions call (git and curl). Our summary lists: Python 3.

Does Wycheproof access the network?

SKILL.md names 5 domains. In commands or code: github.com and raw.githubusercontent.com; the agent is likely to contact these when it follows the instructions. As links in the text: npmjs.com, pypi.org and c2sp.org. This is read from the text; nothing was executed.

Is Wycheproof safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Wycheproof use?

Wycheproof is published under the CC-BY-SA-4.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Wycheproof use?

About 4.9k tokens (SKILL.md is roughly 20k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Wycheproof?

Skills that share tags, products or a category with Wycheproof: Bom Explore (cdxgen/cdxgen, 1.1k stars), Webcrypt MCP (putervision/state-memory-mcp, 111 stars), Crypto Analysis (hypnguyen1209/offensive-claude, 386 stars) and Security Review (valory-xyz/open-autonomy, 129 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Wycheproof?

trailofbits (a GitHub organization, an official publisher) maintains it in trailofbits/skills, which has 7,400 GitHub stars. The repository holds 79 skills in this directory. The repository was last updated on October 2, 2026.

Source: trailofbits/skills on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.