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+<a id="dir-spec.txt-3.2"></a>
+
+# Accepting server descriptor and extra-info document uploads
+
+When a router posts a signed descriptor to a directory authority, the
+authority first checks whether it is well-formed and correctly
+self-signed.  If it is, the authority next verifies that the nickname
+in question is not already assigned to a router with a different
+public key.
+Finally, the authority MAY check that the router is not blacklisted
+because of its key, IP, or another reason.
+
+An authority also keeps a record of all the Ed25519/RSA1024
+identity key pairs that it has seen before.  It rejects any
+descriptor that has a known Ed/RSA identity key that it has
+already seen accompanied by a different RSA/Ed identity key
+in an older descriptor.
+
+At a future date, authorities will begin rejecting all
+descriptors whose RSA key was previously accompanied by an
+Ed25519 key, if the descriptor does not list an Ed25519 key.
+
+At a future date, authorities will begin rejecting all descriptors
+that do not list an Ed25519 key.
+
+If the descriptor passes these tests, and the authority does not already
+have a descriptor for a router with this public key, it accepts the
+descriptor and remembers it.
+
+If the authority _does_ have a descriptor with the same public key, the
+newly uploaded descriptor is remembered if its publication time is more
+recent than the most recent old descriptor for that router, and either:
+
+```text
+      - There are non-cosmetic differences between the old descriptor and the
+        new one.
+      - Enough time has passed between the descriptors' publication times.
+        (Currently, 2 hours.)
+```
+
+Differences between server descriptors are "non-cosmetic" if they would be
+sufficient to force an upload as described in section 2.1 above.
+
+Note that the "cosmetic difference" test only applies to uploaded
+descriptors, not to descriptors that the authority downloads from other
+authorities.
+
+When a router posts a signed extra-info document to a directory authority,
+the authority again checks it for well-formedness and correct signature,
+and checks that its matches the extra-info-digest in some router
+descriptor that it believes is currently useful.  If so, it accepts it and
+stores it and serves it as requested.  If not, it drops it.