tor/changes/bug33545

  o Minor bugfixes (hidden services):
    - Block a client-side assert by disallowing the registration of an x25519
      client auth key that's all zeroes. Fixes bug 33545; bugfix on
      0.4.3.1-alpha. Patch based on patch from "cypherpunks".
hs-v3: Don't allow registration of an all-zeroes client auth key. The client auth protocol allows attacker-controlled x25519 private keys being passed around, which allows an attacker to potentially trigger the all-zeroes assert for client_auth_sk in hs_descriptor.c:decrypt_descriptor_cookie(). We fixed that by making sure that an all-zeroes client auth key will not be used. There are no guidelines for validating x25519 private keys, and the assert was there as a sanity check for code flow issues (we don't want to enter that function with an unitialized key if client auth is being used). To avoid such crashes in the future, we also changed the assert to a BUG-and-err. 2020-03-30 15:09:52 +02:00			`o Minor bugfixes (hidden services):`
			`- Block a client-side assert by disallowing the registration of an x25519`
			`client auth key that's all zeroes. Fixes bug 33545; bugfix on`
			`0.4.3.1-alpha. Patch based on patch from "cypherpunks".`