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docs/supervisor/auth.md

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+## Supervisor Authentication
+
+The supervisor has two authentication systems:
+
+1. An authentication system based on scoped symmetric API keys.
+2. An authentication of the signatures of a job's canonical representation.
+
+The first is used to control access to the supervisor API, the second is used to authenticate the signatories of a job, such that the runners can implement access control based on the signatories.
+
+#### API Key Management
+
+API keys are used to authenticate requests to the supervisor. They are created using the `auth.key.create` method and can be listed using the `key.list` method.
+
+#### API Key Scopes
+
+API keys have a scope that determines what actions they can perform. The following scopes are available:
+
+- `admin`: Full access to all supervisor methods.
+- `registrar`: Access to methods related to job registration and management.
+- `user`: Access to methods related to job execution and management.
+
+#### API Key Usage
+
+API keys are passed as a header in the `Authorization` field of the request. The format is `Bearer <key>`.
+
+#### API Key Rotation
+
+API keys can be rotated using the `key.remove` method. This will invalidate the old key and create a new one.