# cryptoseed-mcp

MCP server for [CryptoSeed](https://github.com/eduardogarcia/CryptoSeed) encryption.
Gives any MCP-compatible AI agent the ability to encrypt and decrypt text and files using ChaCha20-Poly1305 (symmetric) and X25519+HKDF (asymmetric).

Keys are stored in the **macOS Keychain** — never on disk in plain text.
Encrypted `.seed` files are **fully compatible** with the CryptoSeed iOS app.

---

## Setup

### 1. Add to Claude Desktop

Edit `~/Library/Application Support/Claude/claude_desktop_config.json`:

```json
{
  "mcpServers": {
    "cryptoseed": {
      "command": "npx",
      "args": ["-y", "cryptoseed-mcp"]
    }
  }
}
```

Restart Claude Desktop. The 11 CryptoSeed tools will appear automatically.

### 2. Or run directly

```bash
npx cryptoseed-mcp
```

---

## Tools

### Key management (symmetric)
| Tool | Description |
|------|-------------|
| `key_new` | Generate a 256-bit key, save to Keychain |
| `key_list` | List saved key aliases |

### Identity management (asymmetric)
| Tool | Description |
|------|-------------|
| `identity_new` | Generate an X25519 keypair, save private key to Keychain |
| `identity_pubkey` | Print public key as base64 (share with senders) |
| `identity_list` | List saved identity aliases |

### Encrypt
| Tool | Description |
|------|-------------|
| `encrypt_text` | Encrypt text with a symmetric key → base64 |
| `encrypt_file` | Encrypt a file → `.seed` file (CryptoSeed-compatible) |
| `encrypt_asym` | Encrypt a message to a recipient's public key → base64 blob |

### Decrypt
| Tool | Description |
|------|-------------|
| `decrypt_text` | Decrypt base64 ciphertext with a symmetric key |
| `decrypt_file` | Decrypt a `.seed` file, restore original |
| `decrypt_asym` | Decrypt a message encrypted to your identity |

---

## Agent-to-agent encrypted messaging

This is where it gets interesting. Each agent can have its own identity:

```
Agent A creates identity: identity_new "agent_a"
Agent A shares pubkey:    identity_pubkey "agent_a"  →  <pubkey_b64>

Agent B encrypts to A:    encrypt_asym "<pubkey_b64>" "secret payload"  →  <blob>

Agent A decrypts:         decrypt_asym "agent_a" "<blob>"  →  "secret payload"
```

Only Agent A's private key (in its Keychain) can decrypt. The blob can travel through any channel — email, Slack, GitHub, another AI tool — without being readable.

---

## File format compatibility

`.seed` files produced by this MCP server use the exact same binary format as:
- CryptoSeed iOS app
- `cryptoseed` macOS CLI

This means a file encrypted here can be decrypted in the iOS app (after importing the key) and vice versa.

---

## Key transfer between tools

This MCP server and the `cryptoseed` CLI use separate Keychain entries (to avoid binary format conflicts). To use a key from the CLI in the MCP server, use the CLI's export/import commands:

```bash
cryptoseed key export mykey    # → recovery envelope (base64)
# then in Claude: import the envelope via key_new or a future key_import tool
```

---

## Requirements

- macOS (Keychain)
- Node.js >= 18