# encrypt.aauth.dev

> Sends an end-to-end encrypted message for an agent: it takes the messaging service, the recipient, and the text; fetches the recipient's key from that service, encrypts (JWE ECDH-ES A256GCM, P-256), and delivers the ciphertext there, acting for the person over an AAuth call chain. An AAuth resource (access_mode: person-token). Stateless; sees the plaintext, stores nothing. Open code, self-hostable.

Reach it with the AAuth MCP: `connect_resources [{resource: "encrypt.aauth.dev"}]` (the person approves one card; this service sees plaintext), then `invoke sendMessage`.

## The operation

`sendMessage {resource, to, text, from?, idempotency_key?}`

- `resource`: the messaging service to deliver through, as an https origin. Required. The default for agent.coop is `https://secret.agent.coop`; a person using another messaging service names it here.
- `to`: the recipient's identifier URI as that service knows it, e.g. `mailto:bob@example.com`.
- `text`: the message, up to 64 KB. Text only (no attachments yet).
- `from`: one of the sender's identifier URIs at that service, optional.
- `idempotency_key`: optional; a repeat with the same key returns the original.

Returns `{id, to, from, kid, size, resource}`. Refusals from the messaging service pass through with `step`: `not_connected` (404: the person must invite them first), `recipient_has_no_key` (409: they have not finished onboarding), `rate_limited` (429). `text_too_long` (413) and `attachments_not_supported` (400) are this service's. A 502 means the chain failed (`error` is the Person Server's code, or `resource_unreachable`).

The recipient reads with `getMessages` and `getMessage` at the messaging service, then `decryptEnvelope` at https://decrypt.aauth.dev.

## Links

- Metadata: https://encrypt.aauth.dev/.well-known/aauth-resource.json
- Agent document (call chaining): https://encrypt.aauth.dev/.well-known/aauth-agent.json
- OpenAPI: https://encrypt.aauth.dev/openapi.json
- Privacy: https://encrypt.aauth.dev/privacy
- Code and self-hosting: https://github.com/aauth-dev/encrypt
- Container format and vectors: https://github.com/aauth-dev/decrypt-agent-coop/blob/main/spec/container.md
- The default messaging service: https://secret.agent.coop/llms.txt
- The matching decrypt service: https://decrypt.aauth.dev/llms.txt
- Contact: feedback@agent.coop · abuse@agent.coop