MCP Server

Cipher ships with a built-in MCP (Model Context Protocol) server. It lets Claude and other MCP-compatible clients encrypt files, decrypt files, look up public keys, and manage key operations over a JSON-RPC stdio transport.

Start the MCP server

mdstn-cipher mcp

The server communicates over stdin/stdout, which is what Claude Desktop and most MCP clients expect.

Claude Desktop configuration

Add Cipher to your claude_desktop_config.json:

{
  "mcpServers": {
    "cipher": {
      "command": "mdstn-cipher",
      "args": ["mcp"]
    }
  }
}

Restart Claude Desktop; the Cipher tools will appear in the tool panel.

Available MCP tools

The MCP server registers 11 tools:

Tool	Description
`encrypt_file`	Encrypt a file
`decrypt_file`	Decrypt a `.mdstn` file
`create_key`	Create a new key
`list_keys`	List managed keys
`delete_key`	Delete a key
`export_key`	Export a key
`import_key`	Import a key
`get_status`	Report Cipher status
`share_key`	Share a key with another user
`lookup_key`	Look up a public key by email via CKD
`revoke_share`	Revoke a share grant

Security notes

The MCP server runs with the same permissions as your user account and operates on the same local key store. Operations that require your private key follow the same Argon2id-wrapped key model as the CLI; the server never sees raw private keys.