# Authentication

PAD-as-a-Service API uses API keys to authenticate users. All API keys have the prefix `pad`. Each API key identifies a *role* in a particular *instance*. There are 6 roles:

* `Operator`
* `Encryptor`
* `Decryptor`
* `Trustee`
* `Validator`
* `Auditor`

For example, a trustee referencing 3 different instances should have at least 3 different `Trustee` API keys for each instance. He cannot access some of the endpoints disallowed for a `Trustee` role (e.g. uploading an encryption).

## Using an API key

API keys should be provided in the request header `X-API-KEY` field. Making a request missing an API key or with an invalid API key will get a `401 Unauthorized` response.

## Access control list

| URI                                                             | HTTP Method | Operator             | Encryptor            | Decryptor            | Trustee              | Auditor              | Validator            |
| --------------------------------------------------------------- | ----------- | -------------------- | -------------------- | -------------------- | -------------------- | -------------------- | -------------------- |
| /PADs                                                           | `POST`      | :heavy\_check\_mark: |                      |                      |                      |                      |                      |
| /all-trustees                                                   | `GET`       | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: |
| /all-trustees/:trusteeId                                        | `GET`       | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: |
| /all-validators                                                 | `GET`       | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: |
| /all-validators/:validatorId                                    | `GET`       | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: |
| /metadata                                                       | `GET`       | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: |
| /encryptions                                                    | `POST`      | :heavy\_check\_mark: | :heavy\_check\_mark: |                      |                      |                      |                      |
| /encryptions                                                    | `PUT`       | :heavy\_check\_mark: | :heavy\_check\_mark: |                      |                      |                      |                      |
| /encryptions/:tokenHash/status                                  | `GET`       | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: |                      |
| /encryptions/:tokenHash/ciphertext                              | `GET`       | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: |                      |                      |                      |
| /encryptions/:tokenHash/encrypted-trustee-shares/:trusteeId     | `GET`       | :heavy\_check\_mark: |                      | :heavy\_check\_mark: | :heavy\_check\_mark: |                      |                      |
| /encryptions/:tokenHash/hashed-trustee-shares                   | `GET`       | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: |                      |
| /encryptions/:tokenHash/encrypted-validator-shares/:validatorId | `GET`       | :heavy\_check\_mark: |                      | :heavy\_check\_mark: | :heavy\_check\_mark: |                      |                      |
| /data-requests                                                  | `POST`      | :heavy\_check\_mark: | :heavy\_check\_mark: |                      |                      |                      |                      |
| /data-requests                                                  | `GET`       | :heavy\_check\_mark: |                      | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: |                      |
| /data-requests/:token/trustee-responses                         | `POST`      | :heavy\_check\_mark: |                      | :heavy\_check\_mark: |                      |                      |                      |
| /data-requests/:token/trustee-responses                         | `GET`       | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: |                      |                      |
| /data-requests/:token/validator-responses                       | `POST`      | :heavy\_check\_mark: |                      |                      | :heavy\_check\_mark: |                      |                      |
| /data-requests/:token/validator-responses                       | `GET`       | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: |                      |                      |                      |
| /trustee-attestations/:trusteeId                                | `PUT`       | :heavy\_check\_mark: |                      | :heavy\_check\_mark: |                      |                      |                      |
| /trustee-attestations/:trusteeId                                | `GET`       | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: |
| /digest                                                         | `GET`       | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: |
| /ledger                                                         | `GET`       | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: | :heavy\_check\_mark: |

## Rate limiting

We have 2 rate limiting policies: `IP + API_key` and `API_key`. Both have a limit of 100 requests per minute. In the `IP + API_key` policy, if an invalid API key is provided, only the IP is recorded usage of the API. Because of the `API_key` policy, distinct users of the same *role* of an instance should use different API keys. For example, `Trustee-1` and `Trustee-2` who both reference the same instance could use the same API key for serving the instance properly, but this would trigger rate limiting for the API key because the trustees are sharing quotas.

## https

All requests should be made with https protocol. Requests made with http protocol will get a [`301 Moved Permanantly`](https://datatracker.ietf.org/doc/html/rfc7231#section-6.4.2) response directed to https.