PluginBench
MCP Server
Maintained
MIT

WebCrypt MCP Server MCP Server

io.github.putervision/webcrypt

Zero-dependency Web Crypto MCP server with AES-256-GCM, RSA-4096, and post-quantum cryptography for AI agents.

What is the WebCrypt MCP Server MCP server?

WebCrypt MCP Server is a zero-dependency cryptographic vault for AI agents, providing AES-256-GCM symmetric encryption, RSA-4096 hybrid public-key encryption, ECDH key agreement, digital signatures, and post-quantum Kyber/Dilithium support via the Web Crypto API. It enables autonomous coding agents to encrypt sensitive payloads, manage keys, sign artifacts, and perform tamper-proof operations entirely locally without external dependencies.

WebCrypt equips AI agents and IDEs with native cryptographic tooling for confidential local vaulting, tamper-proof provenance, inter-agent key exchange, and post-quantum guardrails. All operations execute locally via the standard Web Crypto API with zero external API calls, making it ideal for securing API keys, state memory, test evidence, and agent-to-agent communication in autonomous workflows.

How to install WebCrypt MCP Server

Copy-paste configuration for popular MCP clients.

transport: stdio
Config generated by PluginBench — verify against the source before use.
~/Library/Application Support/Claude/claude_desktop_config.json
{
  "mcpServers": {
    "webcrypt": {
      "command": "npx",
      "args": [
        "-y",
        "webcrypt"
      ]
    }
  }
}

Tools & capabilities

Tools this server exposes to the agent.

  • encrypt_payload — Encrypt text, JSON objects, or files with AES-256-GCM (symmetric) or RSA-4096 (asymmetric).
  • decrypt_payload — Decrypt ciphertext back to plaintext or structured JSON using symmetric or asymmetric keys.
  • manage_keys — Generate JWK keypairs (RSA, ECDH, ECDSA, RSA-PSS) or high-entropy random passwords.
  • crypto_hash — Compute cryptographic hash digests (SHA-256, SHA-512, SHA-3) in hex or base64 format.
  • sign_verify — Sign and verify messages, release hashes, and evidence packs using ECDSA or HMAC.
  • pqc_kem_sign — Post-quantum Kyber KEM encapsulation and Dilithium signatures for future-proof long-term artifacts.

Use cases

  • Encrypt API keys and sensitive state memory before writing to disk to prevent prompt log leaks
  • Cryptographically sign test evidence packs, release binaries, and code diffs for tamper-proof provenance
  • Generate ephemeral RSA-4096 or ECDH keypairs for private agent-to-agent messaging and key exchange
  • Compute SHA-256/SHA-512 hash digests for integrity verification of artifacts and releases
  • Protect long-term agent artifacts with post-quantum Kyber KEM and Dilithium signatures against future quantum threats

WebCrypt MCP Server MCP server FAQ

What is WebCrypt MCP Server?

WebCrypt is a zero-dependency cryptographic vault MCP server that provides AES-256-GCM symmetric encryption, RSA-4096 asymmetric encryption, ECDH key agreement, digital signatures, and post-quantum cryptography (Kyber/Dilithium) for AI agents. All operations execute locally via the Web Crypto API with no external dependencies or network calls.

Is WebCrypt free?

Yes, WebCrypt is released under the MIT License and is free to use, modify, and distribute.

How do I install WebCrypt in Cursor or Claude Desktop?

Install via npm with `npm install -g webcrypt`, then run `npx webcrypt init` to auto-configure the MCP server for your IDE. The tool supports Cursor, Claude Desktop, VS Code, Copilot, Windsurf, Cline, and Zed.

Does WebCrypt require authentication or API keys?

No. WebCrypt executes 100% locally with zero external API calls, telemetry, or network transmissions. All cryptographic operations use the standard W3C Web Crypto API.

What Node.js versions are supported?

WebCrypt requires Node.js 18.0.0 or higher and also runs on Bun, browsers, and Edge runtimes.

Can I use WebCrypt for inter-agent communication?

Yes. You can generate ephemeral JWK keypairs (RSA-4096, ECDH P-256/P-384) for private agent-to-agent messaging and key exchange.

README (reference)

Source of truth, from the repository.

WebCrypt v1.0.1

Zero-dependency Web Crypto & native AI Agent Tooling (MCP) for modern JavaScript.

npm version npm downloads Node TypeScript MCP Tests Coverage PuterVision Triad License: MIT

AES-256-GCM symmetric encryption, RSA-4096 hybrid public keys, ECDH key agreement, ECDSA/HMAC digital signatures, and Post-Quantum KEM (Kyber/Dilithium) — zero runtime dependencies, pure Web Crypto API.


⚡ Quickstart (15 Seconds)

1. Installation

# 📦 Install as project library (Node.js, TypeScript, Browser)
npm install webcrypt

# 🌐 Install globally (CLI utilities & global MCP tools)
npm install -g webcrypt
import { WebCrypt, WebCryptAsym } from "webcrypt";

// 🔒 Symmetric AES-256-GCM (600k PBKDF2 iterations)
const wc = new WebCrypt();
const encrypted = await wc.encryptText("Secret payload", "password");
const decrypted = await wc.decryptText(encrypted, "password");

// 🔑 Asymmetric RSA-4096 Hybrid Encryption
const wca = new WebCryptAsym();
const keyPair = await wca.generateKeyPair(4096);
const cipher = await wca.encryptText("Secret payload", keyPair.publicKey);
const plain = await wca.decryptText(cipher, keyPair.privateKey);

2. Auto-Setup for AI Agents & IDEs (MCP Server)

# Initialize MCP server, agent skills, and rules across your project
npx webcrypt init  # or `webcrypt init` if installed globally

Supports Google Antigravity, Cursor, Claude Desktop, VS Code / Copilot, Windsurf, Cline, and Zed.


🤖 Why AI Agents Need WebCrypt MCP

Equip autonomous coding agents with an authenticated cryptographic vault directly in their toolbelt:

  • 🔐 Confidential Local Vaulting (encrypt_payload): Encrypt API keys and state memory before writing to disk to prevent prompt log leaks.
  • 🛡️ Tamper-Proof Provenance (sign_verify): Cryptographically sign test evidence packs, release binaries, and code diffs with ECDSA or HMAC.
  • 🤝 Inter-Agent Key Exchange (manage_keys): Ephemeral JWK keypairs (RSA-4096, ECDH P-256/P-384) for private agent-to-agent messaging.
  • ⚛️ Post-Quantum Guardrails (pqc_kem_sign): Built-in Kyber KEM and Dilithium signatures future-proof long-term agent artifacts.
  • ⚡ Zero Dependencies: 100% native crypto.subtle execution across Node.js 18+, Bun, browsers, and Edge runtimes.
┌───────────────────────────────────────────────────────────┐
│              Autonomous AI Coding Agent                   │
│     (Antigravity / Cursor / Claude / Copilot / Cline)     │
└─────────┬───────────────────┬───────────────────┬─────────┘
          │                   │                   │
          ▼                   ▼                   ▼
┌───────────────────┐┌───────────────────┐┌───────────────────┐
│ state-memory-mcp  ││ vision-memory-mcp ││     webcrypt      │
│  (Workflow State) ││  (Visual Cache)   ││  (Security Vault) │
│  • Task Graph DAG ││  • UI Grounding   ││  • AES-256 Vault  │
│  • Decisions & SDD││  • Layout Trees   ││  • RSA/ECDH Keys  │
│  • Event Ledger   ││  • Visual History ││  • Digital Sigs   │
└───────────────────┘└───────────────────┘└───────────────────┘

🛠️ MCP Tools Reference (6 Core Tools)

ToolAction / ModeDescription
encrypt_payloadsymmetric | asymmetric | dataEncrypt text, JSON objects, or files with AES-256-GCM or RSA-4096.
decrypt_payloadsymmetric | asymmetric | dataDecrypt ciphertext back to plaintext or structured JSON.
manage_keysgenerate | generate_random_passwordGenerate JWK keypairs (RSA, ECDH, ECDSA, RSA-PSS) or high-entropy passwords.
crypto_hashSHA-256 | SHA-512 | SHA-3Compute cryptographic hash digests in hex or base64.
sign_verifysign | verifySign and verify messages, release hashes, and evidence packs.
pqc_kem_signkyber_* | dilithium_* | hybrid_*Post-quantum Kyber KEM encapsulation and Dilithium signatures.

📚 Technical Documentation Directory

Explore dedicated guides in docs/ and examples/:

GuideTopic
🚀 Live Interactive PlaygroundTest all crypto features in the browser demo.
💻 CLI Reference GuideScaffolding, global project scanning, and terminal utilities.
⚙️ Multi-IDE MCP Setup GuideStep-by-step MCP JSON configs for all major IDEs.
🔒 Symmetric Encryption API (WebCrypt)AES-256-GCM, streaming files, WebRTC E2EE, PBKDF2.
🔑 Asymmetric Encryption API (WebCryptAsym)RSA-4096 hybrid, ECDH key agreement, ECDSA/RSA-PSS.
⚛️ Post-Quantum Cryptography GuideKyber KEM, Dilithium signatures, and Hybrid KEM.
🏗️ Architecture & MCP SpecificationsStdio JSON-RPC 2.0 protocol and chunk framing specs.
🤖 Agent Skill DefinitionCustom agent skill with automated test runner script.
📋 Project Instructions TemplateMulti-agent rules template (<!-- webcrypt-mcp:start -->).
💡 Code Examples DirectoryReady-to-run Node.js & browser recipes.

🌐 PuterVision Triad Standard

  • 📊 @putervision/state-memory-mcp: Persistent SQLite graph for workflow states, task DAGs, and decision trails.
  • 👁️ @putervision/vision-memory-mcp: Multimodal visual layout cache, AX grounding, and video replay analysis.
  • 🔐 webcrypt: Zero-dependency cryptographic vault, payload encryption, key management, and digital signatures.

🧪 Testing & Diagnostics

# Run unit & integration test matrix (30 suites, 247 tests)
npm test

# Run live MCP tool test runner (25 assertions, 100% verified)
node .agents/skills/webcrypt-mcp/scripts/exercise_tools.js

# Audit environment & project configuration health
webcrypt doctor

⚖️ License & Disclaimers

Developed and maintained by PuterVision. Released under the MIT License.

  • 100% Local Execution Guarantee: All cryptographic operations execute locally in memory via standard W3C Web Crypto API (crypto.subtle). Zero external API calls, telemetry, or network transmissions.
  • Trademarks & Non-Affiliation: Product names (Cursor, Claude, Google Antigravity, VS Code, GitHub Copilot, Windsurf, Cline, Zed) are property of their respective owners and used solely for compatibility identification.

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