npm install

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

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

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

npm run mcp:inspect

# Run all tests once
npm test

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

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

// package.json
"dependencies": {
  "@modelcontextprotocol/sdk": "^1.27.1",
  "@types/node": "^24.11.0",
  "zod": "^3.25.76"
}

// src/index.ts
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import { server } from "./mcp.ts";

async function main() {
    const transport = new StdioServerTransport()
    await server.connect(transport)
    console.error('Encrypt MCP Server running on stdio')
}

main().catch((error) => {
    console.error("Fatal error in main():", error);
    process.exit(1);
});

// src/mcp.ts
import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";

export const server = new McpServer({
    name: '@igorromero/ciphersuite-mcp',
    version: '0.0.1'
})

server.registerTool(
    'encrypt_message',
    {
        description: 'Encrypt a message',
        inputSchema: {
            message: z.string().describe("The message to encrypt"),
            encryptionKey: z.string().describe(
                "Any passphrase to use for encryption — the server derives a strong key from it automatically"
            )
        },
        outputSchema: {
            encryptedMessage: z.string().describe(
                "The encrypted message (format: iv:ciphertext)"
            )
        }
    },
    async ({ message, encryptionKey }) => {
        try {
            const encryptedMessage = encrypt(message, encryptionKey)
            return {
                content: [{ type: "text", text: encryptedMessage }],
                structuredContent: { encryptedMessage }
            }
        } catch (error) {
            return {
                isError: true,
                content: [{
                    type: 'text',
                    text: `Failed to encrypt message! Error: ${error instanceof Error ? error.message : String(error)}`
                }]
            }
        }
    }
)

server.registerResource(
    'encryption://info',
    'encryption://info',
    {
        description: 'Describes the encryption algorithm, key requirements, and output format used by this server',
    },
    () => ({
        contents: [
            {
                uri: "encryption://info",
                mimeType: "text/plain",
                text: `
Algorithm : AES-256-CBC
Key derivation: scrypt (passphrase + fixed server salt → 32-byte key)
Output format: <16-byte IV in hex>:<ciphertext in hex>  (separated by ":")
Notes:
  - Users pass any passphrase — the server derives a strong 32-byte key automatically using scrypt.
  - A random IV is generated for every encryption — the same message encrypted twice will produce different output.
  - Use the exact same passphrase to decrypt.
  - Keep the full "iv:ciphertext" string to decrypt later.
                `.trim(),
            },
        ]
    })
)

server.registerPrompt(
    "encrypt_message_prompt",
    {
        description: "Prompt to encrypt a plain-text message using the encrypt_message tool",
        argsSchema: {
            message: z.string().describe("The message to encrypt"),
            encryptionKey: z.string().describe(
                "Any passphrase to use for encryption — the server derives a strong key from it automatically"
            )
        }
    },
    ({ message, encryptionKey }) => ({
        messages: [
            {
                role: 'user',
                content: {
                    type: "text",
                    text: `Please encrypt the following message using the encrypt_message tool.\nMessage: ${message}\nEncryption key: ${encryptionKey}`,
                }
            }
        ]
    })
)

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