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This content is for SDK V4. For the latest version, see the V5 documentation.
This section contains an advanced discussion of Ditto’s underlying certificate, identity, and encryption implementation. Most readers can skip this section. However, if you are deploying an enterprise on-premises deployment of Ditto, you may be required to reference the following material.
Cryptographically-signed business rules ensure users can only sync data that they are permitted to access. The app developer is in complete control of the keys, certificates, and rules. Ditto Server provisions a signed x509 certificate. This certificate may then be presented to other Ditto peers to mutually establish trust and create encrypted communications channels. The following details information about the certificates used to encrypt the communication channels.

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Identities

An identity is a bundle of the device and app-specific information:

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Certificates

Ditto identities and public keys are distributed in the standard X.509 certificate format. They do not directly contain potentially sensitive data such as access rules, but these can be defined by the app’s authentication webhook with the OnlineWithAuthentication identity, or by the developer through the Manual identity. When you are ready to use production identities, feel free to contact us through the Ditto Portal and we will help you set up the right CA tooling for your use case - or provide specifications so you can build your own.

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Discovering peers

Devices need to have the same AppID to discover other peers on the network, as well as matching certificates to connect over TLS 1.3. Peer-to-peer connections use mTLS (client certificates) with TLS 1.3. Connections to Ditto Server use a TLS-secured WebSocket connection, with authentication by JWT. Once the certificates match, then the embedded authorization information inside each certificate is used to authorize any incoming requests by that peer. This ensures that those access control rules are enforced.

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Syncing with Ditto Server

This covers internal details of the Ditto Server implementation. Ditto’s authentication module handles it for you under the hood as part of the OnlineWithAuthentication and OnlinePlayground identities.
Online Authentication is used when a Ditto application is hosted on Ditto Server, which runs an HTTPS identity service that handles login requests. A Small Peer must log in with credentials before it can communicate with any peers; a successful login populates it with the authentication material that identifies the user and defines their level of access, after which the transports that depend on it start automatically. For the step-by-step login flow — the peer key challenge, credential issuance, and on-disk persistence — see Detailed Online Certificate Flow.

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Rationale

Why does X.509 return both a key and a certificate instead of locally generating a key and sending a CSR? It would be possible to use a standard CSR flow. It was chosen to issue keys directly for a few reasons.
  • There is no security benefit as our certificate request is in a secured tunnel, and the identity service is presumed to be completely trustworthy.
  • Validating and signing CSRs is more complex than simply creating one with the correct format and fields.
  • This is a convenient workflow if using Hashicorp Vault or similar to manage your PKI and issue certificates on demand.