@erickwendel/ciphersuite-mcp

An MCP (Model Context Protocol) server that provides AES-256-CBC encryption and decryption tools, a resource describing the algorithm, and ready-to-use prompts — all runnable directly inside VS Code Copilot Chat.

What it does

| Capability | Name | Description | |---|---|---| | 🔧 Tool | encrypt_message | Encrypts any plain-text message with a passphrase | | 🔧 Tool | decrypt_message | Decrypts a previously encrypted message with the same passphrase | | 📄 Resource | encryption://info | Returns details about the algorithm, key derivation, and output format | | 💬 Prompt | encrypt_message_prompt | Pre-built prompt that asks the agent to encrypt a message | | 💬 Prompt | decrypt_message_prompt | Pre-built prompt that asks the agent to decrypt a message |

How encryption works

• Algorithm: AES-256-CBC
• Key derivation: scrypt(passphrase, fixedSalt, 32) — you pass any passphrase string; the server derives a strong 32-byte key automatically
• Output format: <IV in hex>:<ciphertext in hex> — keep the full string to decrypt later
• IV: a fresh random 16-byte IV is generated on every encryption call, so the same message encrypted twice produces different output

Prerequisites

• Node.js v24+ (see engines in package.json)

Installation

npm install

No build step is needed — the server runs TypeScript directly via Node.js native TypeScript support.

Using in VS Code

1. Add the MCP server configuration

Create (or open) .vscode/mcp.json in your workspace and add:

{
  "servers": {
    "ciphersuite-mcp": {
      "command": "node",
      "args": ["--experimental-strip-types", "ABSOLUTE_PATH_TO_PROJECT/src/index.ts"]
    }
  }
}

or via npm

{
  "servers": {
    "ciphersuite-mcp": {
      "command": "npx",
      "args": ["-y", "@erickwendel/ciphersuite-mcp"]
    }
  }
}

Tip: You can also add this server to your user-level MCP config at ~/.vscode/mcp.json to make it available in every workspace.

2. Reload VS Code

Open the Command Palette (Cmd+Shift+P) and run Developer: Reload Window (or just restart VS Code).

3. Use it in Copilot Chat

Open Copilot Chat (Agent mode) and try:

Encrypt the message "Hello, World!" using the passphrase "my-secret-key"

Decrypt this message: a3f1...:<ciphertext> using the passphrase "my-secret-key"

Show me the encryption://info resource

The agent will automatically call the appropriate tool and return the result.

Running the MCP Inspector

The MCP Inspector lets you explore and test all tools, resources, and prompts interactively in a browser UI:

npm run mcp:inspect

This opens the inspector at http://localhost:5173 and connects it to the running server.

Running tests

# Run all tests once
npm test

# Run tests in watch mode (with debugger)
npm run test:dev

The test suite covers:

• Encrypting a message
• Decrypting a message with the correct passphrase
• Listing and reading the encryption://info resource
• Fetching both prompts
• Error: decrypting with the wrong passphrase
• Error: decrypting a malformed ciphertext

Project structure

src/
  index.ts   # Entry point — connects the server to stdio transport
  mcp.ts     # All tools, resources, and prompts are registered here
tests/
  mcp.test.ts

Available scripts

| Script | Description | |---|---| | npm start | Start the server (used by MCP clients) | | npm run dev | Start with file-watch and Node.js inspector | | npm test | Run all tests | | npm run test:dev | Run tests in watch mode | | npm run mcp:inspect | Open the MCP Inspector UI |