@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.

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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

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Prerequisites

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

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Installation

npm install

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

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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.

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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.

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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

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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

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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