{"action":"created","issue":{"url":"https://api.github.com/repos/otrv4/otrv4/issues/182","repository_url":"https://api.github.com/repos/otrv4/otrv4","labels_url":"https://api.github.com/repos/otrv4/otrv4/issues/182/labels{/name}","comments_url":"https://api.github.com/repos/otrv4/otrv4/issues/182/comments","events_url":"https://api.github.com/repos/otrv4/otrv4/issues/182/events","html_url":"https://github.com/otrv4/otrv4/issues/182","id":360641897,"node_id":"MDU6SXNzdWUzNjA2NDE4OTc=","number":182,"title":"Party receiving TLV type 1 does not reveal final MAC keys?","user":{"login":"cobratbq","id":1936470,"node_id":"MDQ6VXNlcjE5MzY0NzA=","avatar_url":"https://avatars0.githubusercontent.com/u/1936470?v=4","gravatar_id":"","url":"https://api.github.com/users/cobratbq","html_url":"https://github.com/cobratbq","followers_url":"https://api.github.com/users/cobratbq/followers","following_url":"https://api.github.com/users/cobratbq/following{/other_user}","gists_url":"https://api.github.com/users/cobratbq/gists{/gist_id}","starred_url":"https://api.github.com/users/cobratbq/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/cobratbq/subscriptions","organizations_url":"https://api.github.com/users/cobratbq/orgs","repos_url":"https://api.github.com/users/cobratbq/repos","events_url":"https://api.github.com/users/cobratbq/events{/privacy}","received_events_url":"https://api.github.com/users/cobratbq/received_events","type":"User","site_admin":false},"labels":[],"state":"closed","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":1,"created_at":"2018-09-16T13:56:24Z","updated_at":"2018-09-16T16:49:45Z","closed_at":"2018-09-16T16:18:30Z","author_association":"CONTRIBUTOR","body":"[Section \"Revealing MAC Keys\"](https://github.com/otrv4/otrv4/blob/master/otrv4.md#revealing-mac-keys) describes how we either expose used MAC keys on every first message of a new ratchet (message ID == 0) or when disconnecting (sending remaining MAC keys as TLV type 1 payload). However, there is also the receiving party.\r\n\r\n*How does the receiving party act when receiving a TLV type 1 (DISCONNECT)?* It may still have a number of MAC-keys-to-reveal. However, the session has been ended on the opposite site, so how do we now reveal the remaining MAC keys?\r\n\r\nI hope I am understanding the rotation correctly. This would not be an issue in OTRv3 due to that version using a different ratcheting mechanism. I believe this is a problem for OTRv4 in case multiple messages are sent with the last message containing TLV 1. (I.e. the receiving party would be saving up MAC keys but never gets an opportunity to send them.)"},"comment":{"url":"https://api.github.com/repos/otrv4/otrv4/issues/comments/421794710","html_url":"https://github.com/otrv4/otrv4/issues/182#issuecomment-421794710","issue_url":"https://api.github.com/repos/otrv4/otrv4/issues/182","id":421794710,"node_id":"MDEyOklzc3VlQ29tbWVudDQyMTc5NDcxMA==","user":{"login":"cobratbq","id":1936470,"node_id":"MDQ6VXNlcjE5MzY0NzA=","avatar_url":"https://avatars0.githubusercontent.com/u/1936470?v=4","gravatar_id":"","url":"https://api.github.com/users/cobratbq","html_url":"https://github.com/cobratbq","followers_url":"https://api.github.com/users/cobratbq/followers","following_url":"https://api.github.com/users/cobratbq/following{/other_user}","gists_url":"https://api.github.com/users/cobratbq/gists{/gist_id}","starred_url":"https://api.github.com/users/cobratbq/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/cobratbq/subscriptions","organizations_url":"https://api.github.com/users/cobratbq/orgs","repos_url":"https://api.github.com/users/cobratbq/repos","events_url":"https://api.github.com/users/cobratbq/events{/privacy}","received_events_url":"https://api.github.com/users/cobratbq/received_events","type":"User","site_admin":false},"created_at":"2018-09-16T16:49:45Z","updated_at":"2018-09-16T16:49:45Z","author_association":"CONTRIBUTOR","body":"I understand that one party's sender keys are equal to the other party's receiver keys. (Otherwise decrypting or verifying a message wouldn't be possible.) However, one party's receiving keys are different from its sending keys, right? (Or said differently, the keys are present at both parties, but only one party is expected to reveal them and each party reveals a different set of keys.)\r\n\r\nNote that TLV type 1 is also sent when user ends the encrypted session. ([\"User requests to end an OTR Conversation\"](https://github.com/otrv4/otrv4/blob/master/otrv4.md#user-requests-to-end-an-otr-conversation))\r\n\r\nOn revealing not being a critical activity anymore: Okay. Good to know."}}
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