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Secrets ​

Encrypted secret storage for MCP server credentials. Secrets are stored per-user in MongoDB with AES-256-GCM encryption and automatically injected into tool calls.

Endpoints ​

POST /secrets/set ​

Store a secret value for a specific user and MCP server. The secret is encrypted before storage.

bash
curl -X POST http://mcp:8082/secrets/set \
  -H "Content-Type: application/json" \
  -d '{
    "username": "user123",
    "serverName": "github",
    "secretName": "GITHUB_TOKEN",
    "secretValue": "ghp_xxxxxxxxxxxx"
  }'
FieldTypeRequiredDescription
usernamestringNoUsername to associate the secret with. Defaults to "default"
serverNamestringYesName of the MCP server that will use this secret
secretNamestringYesSecret identifier (e.g., "API_KEY", "GITHUB_TOKEN")
secretValuestringYesThe secret value to store

Response:

json
{ "success": true }

When a secret is set:

  1. The system verifies the specified server exists
  2. The secret value is encrypted using AES-256-GCM
  3. The encrypted secret is stored in MongoDB, associated with the username and server
  4. If a secret with the same name already exists for this user and server, it is overwritten

Secrets stored with this endpoint are automatically injected into tool calls made with POST /mcp/tool/call when the same username and server name are specified.

POST /secrets/delete ​

Remove a stored secret.

bash
curl -X POST http://mcp:8082/secrets/delete \
  -H "Content-Type: application/json" \
  -d '{
    "username": "user123",
    "serverName": "github",
    "secretName": "GITHUB_TOKEN"
  }'
FieldTypeRequiredDescription
usernamestringNoUsername associated with the secret. Defaults to "default"
serverNamestringYesMCP server the secret is associated with
secretNamestringYesName of the secret to delete

Response:

json
{ "success": true }

The secret is permanently removed. Future tool calls will no longer have this secret injected.

Security Model ​

The MCP API implements a layered security model for secret handling:

  1. Encryption at rest: All secrets are encrypted using AES-256-GCM before storage. Each encrypted value is stored as iv:authTag:ciphertext (hex-encoded). The encryption key is configured via the SECRETS_KEY environment variable.

  2. User isolation: Each user's secrets are stored separately, keyed by (username, serverName, secretName). Multiple users can use the same MCP servers with different credentials.

  3. Just-in-time decryption: Secrets are only decrypted when needed for a specific tool call and are not stored in plaintext in memory longer than necessary.

  4. Transparent injection: Secrets are automatically injected into tool call arguments by the MCP API. Clients never need to handle or expose sensitive information in their requests.

  5. No secret enumeration: There is no API endpoint to list stored secrets, reducing the risk of information disclosure.

Production Requirements ​

  • Change SECRETS_KEY: The default value (secret) is for development only. Generate a strong key with openssl rand -hex 32.
  • Use HTTPS: Protect data in transit if the MCP API is accessed over a network.
  • Restrict network access: The MCP API should only be reachable by the MissionSquad API and authorized administrators via private networking.
  • Rotate encryption keys: Periodically rotate SECRETS_KEY and re-encrypt stored secrets.

See also ​