[bot]update openapi3 schema

Author: github-actions[bot]

api/build/core-openapi3.yaml

@@ -16,26 +16,6 @@ tags:
   - name: Resource addressing with relative roots - Registration not required
   - name: Resource addressing with relative roots - Registration required
 paths:
-  /.p2/core/v1/challenge:
-    get:
-      operationId: Unregistered_challengeString
-      summary: Receive a challenge string
-      description: |-
-        Request a challenge string. See the corresponding
-        [protocol definition chapter](https://docs.polyphony.chat/Protocol%20Specifications/core/#42-challenge-strings)
-        for more information.
-      parameters: []
-      responses:
-        '200':
-          description: The request has succeeded.
-          content:
-            application/json:
-              schema:
-                $ref: '#/components/schemas/polyproto.core.models.ChallengeStringResponse'
-      tags:
-        - Federated Identity - Registration not required
-      security:
-        - BearerAuth: []
   /.p2/core/v1/data:
     delete:
       operationId: Unregistered_deleteData
@@ -1472,8 +1452,8 @@ paths:
       summary: Upload encrypted private key material
       description: |-
         Upload encrypted private key material to the server for later retrieval. The size of
-        the individual array elements must not exceed 
-        the server's maximum upload size for this route. This is usually not more than 10kb and can be as 
+        the individual array elements must not exceed
+        the server's maximum upload size for this route. This is usually not more than 10kb and can be as
         low as 800 bytes, depending on the server configuration.
       parameters: []
       responses:
@@ -1648,31 +1628,8 @@ components:
           example: 7ab2bbde7fe43c7481a3a61031546bab16bc1a8735b2f0cdd519958c7f2f99f8
           minLength: 32
           maxLength: 32
-          description: Signature generated by the home server. This signature can be verified using the home servers' public identity key. A server generates the `cacheSignature` by concatenating the serial number of the ID-Cert in question with the `cacheValidNotBefore` timestamp and the `cacheValidNotAfter` timestamp, then generating the signature of the resulting concatenated string using the private identity key of the server. Clients must reject certificates of which the `cacheSignature` can not be verified to be correct.
+          description: Signature generated by the home server, encoded in [Hexadecimal](https://en.wikipedia.org/wiki/Hexadecimal) (base-16). This signature can be verified using the home servers' public identity key. A server generates the `cacheSignature` by concatenating the serial number of the ID-Cert in question with the `cacheValidNotBefore` timestamp, the `cacheValidNotAfter` timestamp, and the `invalidatedAt` timestamp, if present. Clients must reject certificates of which the `cacheSignature` can not be verified to be correct.
       description: A cacheable response to an ID-Cert request.
-    polyproto.core.models.ChallengeStringResponse:
-      type: object
-      required:
-        - challenge
-        - expires
-      properties:
-        challenge:
-          type: string
-          minLength: 32
-          maxLength: 256
-          description: The challenge string, which the client should sign with its private identity key.
-        expires:
-          type: integer
-          format: uint64
-          description: The UNIX timestamp after which the challenge expires.
-      description: |-
-        A challenge string response, as received from a server when requesting a challenge string.
-
-        From the polyproto protocol definition: "verify an actor's private identity key possession,
-        without revealing the private key itself. These strings, ranging from 32 to 256 characters,
-        have a UNIX timestamp lifetime. If the current timestamp surpasses this lifetime, the
-        challenge fails. The actor signs the string, sending the signature and their ID-Cert to the
-        server, which then verifies the signature's authenticity."
     polyproto.core.models.EncryptedPKM:
       type: object
       required: