{"action":"created","comment":{"url":"https://api.github.com/repos/mlswg/mls-protocol/pulls/comments/214485784","pull_request_review_id":150353874,"id":214485784,"node_id":"MDI0OlB1bGxSZXF1ZXN0UmV2aWV3Q29tbWVudDIxNDQ4NTc4NA==","diff_hunk":"@@ -1435,44 +1465,230 @@ all arrive at the following state:\n \n # Message Protection\n \n-[[ OPEN ISSUE: This section has initial considerations about message\n-protection.  This issue clearly needs more specific recommendations,\n-possibly a protocol specification in this document or a separate\n-one. ]]\n+The primary purpose of the handshake protocol is to provide an authenticated\n+group key exchange to participants. In order to protect Application messages\n+sent among those participants, the Application secret provided by the Handshake\n+key schedule is used to derive encryption keys for the Message Protection Layer.\n+\n+Application messages MUST be protected with the Authenticated-Encryption\n+with Associated-Data (AEAD) encryption scheme associated with the MLS ciphersuite.\n+Note that \"Authenticated\" in this context does not mean messages are known to\n+be sent by a specific participant but only from a legitimate member of the group.\n+To authenticate a message from a particular member, signatures are required.\n+Handshake messages MUST use asymmetric signatures\n+to strongly authenticate the sender of a message; Application messages SHOULD\n+use the signature scheme to provide the same property.\n+\n+Each participant maintains their own chain of Application secrets, where the first\n+one is derived based on a secret chained from the Epoch secret.\n+As shown in {{key-schedule}}, the initial Application secret is bound to the\n+identity of each participant to avoid collisions and allow support for decryption\n+of reordered messages.\n+\n+Subsequent Application secrets MUST be rotated for each Application message, independently\n+from the Group secret updates, in order to provide stronger cryptographic\n+security properties for messages. To later encrypt and decrypt Application messages,\n+we use this secret to derive AEAD encryption key and nonce.\n+In all cases, a participant MUST NOT encrypt more than expected by the AEAD scheme\n+with Nonces and keys generated from the same Application secrets.\n+\n+[[OPEN ISSUE: The AEAD key exhaustion bound applies on a per Application\n+Secret basis. This depends on the number of messages per Application secrets\n+that we allow. Should we set a limit ?\n+]]","path":"draft-ietf-mls-protocol.md","position":120,"original_position":120,"commit_id":"234897d64d47590b298e44343c23b623ec4f4c78","original_commit_id":"234897d64d47590b298e44343c23b623ec4f4c78","user":{"login":"ekr","id":1111457,"node_id":"MDQ6VXNlcjExMTE0NTc=","avatar_url":"https://avatars0.githubusercontent.com/u/1111457?v=4","gravatar_id":"","url":"https://api.github.com/users/ekr","html_url":"https://github.com/ekr","followers_url":"https://api.github.com/users/ekr/followers","following_url":"https://api.github.com/users/ekr/following{/other_user}","gists_url":"https://api.github.com/users/ekr/gists{/gist_id}","starred_url":"https://api.github.com/users/ekr/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/ekr/subscriptions","organizations_url":"https://api.github.com/users/ekr/orgs","repos_url":"https://api.github.com/users/ekr/repos","events_url":"https://api.github.com/users/ekr/events{/privacy}","received_events_url":"https://api.github.com/users/ekr/received_events","type":"User","site_admin":false},"body":"I'm not following this. The rules here require one AEAD per key/nonce pair.","created_at":"2018-08-31T22:07:24Z","updated_at":"2018-08-31T22:14:41Z","html_url":"https://github.com/mlswg/mls-protocol/pull/54#discussion_r214485784","pull_request_url":"https://api.github.com/repos/mlswg/mls-protocol/pulls/54","author_association":"COLLABORATOR","_links":{"self":{"href":"https://api.github.com/repos/mlswg/mls-protocol/pulls/comments/214485784"},"html":{"href":"https://github.com/mlswg/mls-protocol/pull/54#discussion_r214485784"},"pull_request":{"href":"https://api.github.com/repos/mlswg/mls-protocol/pulls/54"}}},"pull_request":{"url":"https://api.github.com/repos/mlswg/mls-protocol/pulls/54","id":201690777,"node_id":"MDExOlB1bGxSZXF1ZXN0MjAxNjkwNzc3","html_url":"https://github.com/mlswg/mls-protocol/pull/54","diff_url":"https://github.com/mlswg/mls-protocol/pull/54.diff","patch_url":"https://github.com/mlswg/mls-protocol/pull/54.patch","issue_url":"https://api.github.com/repos/mlswg/mls-protocol/issues/54","number":54,"state":"open","locked":false,"title":"Message Protection","user":{"login":"beurdouche","id":1193431,"node_id":"MDQ6VXNlcjExOTM0MzE=","avatar_url":"https://avatars0.githubusercontent.com/u/1193431?v=4","gravatar_id":"","url":"https://api.github.com/users/beurdouche","html_url":"https://github.com/beurdouche","followers_url":"https://api.github.com/users/beurdouche/followers","following_url":"https://api.github.com/users/beurdouche/following{/other_user}","gists_url":"https://api.github.com/users/beurdouche/gists{/gist_id}","starred_url":"https://api.github.com/users/beurdouche/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/beurdouche/subscriptions","organizations_url":"https://api.github.com/users/beurdouche/orgs","repos_url":"https://api.github.com/users/beurdouche/repos","events_url":"https://api.github.com/users/beurdouche/events{/privacy}","received_events_url":"https://api.github.com/users/beurdouche/received_events","type":"User","site_admin":false},"body":"This is one of the options regarding Message Protection discussed in Montreal...","created_at":"2018-07-16T16:25:35Z","updated_at":"2018-08-31T22:14:41Z","closed_at":null,"merged_at":null,"merge_commit_sha":"981732c2142d025ef5ed01453a432dcf751280b5","assignee":null,"assignees":[],"requested_reviewers":[],"requested_teams":[],"labels":[],"milestone":null,"commits_url":"https://api.github.com/repos/mlswg/mls-protocol/pulls/54/commits","review_comments_url":"https://api.github.com/repos/mlswg/mls-protocol/pulls/54/comments","review_comment_url":"https://api.github.com/repos/mlswg/mls-protocol/pulls/comments{/number}","comments_url":"https://api.github.com/repos/mlswg/mls-protocol/issues/54/comments","statuses_url":"https://api.github.com/repos/mlswg/mls-protocol/statuses/234897d64d47590b298e44343c23b623ec4f4c78","head":{"label":"mlswg:upstream/beurdouche_msgprotection","ref":"upstream/beurdouche_msgprotection","sha":"234897d64d47590b298e44343c23b623ec4f4c78","user":{"login":"mlswg","id":36107802,"node_id":"MDEyOk9yZ2FuaXphdGlvbjM2MTA3ODAy","avatar_url":"https://avatars3.githubusercontent.com/u/36107802?v=4","gravatar_id":"","url":"https://api.github.com/users/mlswg","html_url":"https://github.com/mlswg","followers_url":"https://api.github.com/users/mlswg/followers","following_url":"https://api.github.com/users/mlswg/following{/other_user}","gists_url":"https://api.github.com/users/mlswg/gists{/gist_id}","starred_url":"https://api.github.com/users/mlswg/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/mlswg/subscriptions","organizations_url":"https://api.github.com/users/mlswg/orgs","repos_url":"https://api.github.com/users/mlswg/repos","events_url":"https://api.github.com/users/mlswg/events{/privacy}","received_events_url":"https://api.github.com/users/mlswg/received_events","type":"Organization","site_admin":false},"repo":{"id":109873129,"node_id":"MDEwOlJlcG9zaXRvcnkxMDk4NzMxMjk=","name":"mls-protocol","full_name":"mlswg/mls-protocol","owner":{"login":"mlswg","id":36107802,"node_id":"MDEyOk9yZ2FuaXphdGlvbjM2MTA3ODAy","avatar_url":"https://avatars3.githubusercontent.com/u/36107802?v=4","gravatar_id":"","url":"https://api.github.com/users/mlswg","html_url":"https://github.com/mlswg","followers_url":"https://api.github.com/users/mlswg/followers","following_url":"https://api.github.com/users/mlswg/following{/other_user}","gists_url":"https://api.github.com/users/mlswg/gists{/gist_id}","starred_url":"https://api.github.com/users/mlswg/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/mlswg/subscriptions","organizations_url":"https://api.github.com/users/mlswg/orgs","repos_url":"https://api.github.com/users/mlswg/repos","events_url":"https://api.github.com/users/mlswg/events{/privacy}","received_events_url":"https://api.github.com/users/mlswg/received_events","type":"Organization","site_admin":false},"private":false,"html_url":"https://github.com/mlswg/mls-protocol","description":"MLS protocol","fork":false,"url":"https://api.github.com/repos/mlswg/mls-protocol","forks_url":"https://api.github.com/repos/mlswg/mls-protocol/forks","keys_url":"https://api.github.com/repos/mlswg/mls-protocol/keys{/key_id}","collaborators_url":"https://api.github.com/repos/mlswg/mls-protocol/collaborators{/collaborator}","teams_url":"https://api.github.com/repos/mlswg/mls-protocol/teams","hooks_url":"https://api.github.com/repos/mlswg/mls-protocol/hooks","issue_events_url":"https://api.github.com/repos/mlswg/mls-protocol/issues/events{/number}","events_url":"https://api.github.com/repos/mlswg/mls-protocol/events","assignees_url":"https://api.github.com/repos/mlswg/mls-protocol/assignees{/user}","branches_url":"https://api.github.com/repos/mlswg/mls-protocol/branches{/branch}","tags_url":"https://api.github.com/repos/mlswg/mls-protocol/tags","blobs_url":"https://api.github.com/repos/mlswg/mls-protocol/git/blobs{/sha}","git_tags_url":"https://api.github.com/repos/mlswg/mls-protocol/git/tags{/sha}","git_refs_url":"https://api.github.com/repos/mlswg/mls-protocol/git/refs{/sha}","trees_url":"https://api.github.com/repos/mlswg/mls-protocol/git/trees{/sha}","statuses_url":"https://api.github.com/repos/mlswg/mls-protocol/statuses/{sha}","languages_url":"https://api.github.com/repos/mlswg/mls-protocol/languages","stargazers_url":"https://api.github.com/repos/mlswg/mls-protocol/stargazers","contributors_url":"https://api.github.com/repos/mlswg/mls-protocol/contributors","subscribers_url":"https://api.github.com/repos/mlswg/mls-protocol/subscribers","subscription_url":"https://api.github.com/repos/mlswg/mls-protocol/subscription","commits_url":"https://api.github.com/repos/mlswg/mls-protocol/commits{/sha}","git_commits_url":"https://api.github.com/repos/mlswg/mls-protocol/git/commits{/sha}","comments_url":"https://api.github.com/repos/mlswg/mls-protocol/comments{/number}","issue_comment_url":"https://api.github.com/repos/mlswg/mls-protocol/issues/comments{/number}","contents_url":"https://api.github.com/repos/mlswg/mls-protocol/contents/{+path}","compare_url":"https://api.github.com/repos/mlswg/mls-protocol/compare/{base}...{head}","merges_url":"https://api.github.com/repos/mlswg/mls-protocol/merges","archive_url":"https://api.github.com/repos/mlswg/mls-protocol/{archive_format}{/ref}","downloads_url":"https://api.github.com/repos/mlswg/mls-protocol/downloads","issues_url":"https://api.github.com/repos/mlswg/mls-protocol/issues{/number}","pulls_url":"https://api.github.com/repos/mlswg/mls-protocol/pulls{/number}","milestones_url":"https://api.github.com/repos/mlswg/mls-protocol/milestones{/number}","notifications_url":"https://api.github.com/repos/mlswg/mls-protocol/notifications{?since,all,participating}","labels_url":"https://api.github.com/repos/mlswg/mls-protocol/labels{/name}","releases_url":"https://api.github.com/repos/mlswg/mls-protocol/releases{/id}","deployments_url":"https://api.github.com/repos/mlswg/mls-protocol/deployments","created_at":"2017-11-07T18:14:24Z","updated_at":"2018-08-31T21:40:46Z","pushed_at":"2018-08-31T21:40:44Z","git_url":"git://github.com/mlswg/mls-protocol.git","ssh_url":"git@github.com:mlswg/mls-protocol.git","clone_url":"https://github.com/mlswg/mls-protocol.git","svn_url":"https://github.com/mlswg/mls-protocol","homepage":null,"size":337,"stargazers_count":23,"watchers_count":23,"language":"Makefile","has_issues":true,"has_projects":false,"has_downloads":true,"has_wiki":true,"has_pages":false,"forks_count":5,"mirror_url":null,"archived":false,"open_issues_count":9,"license":{"key":"other","name":"Other","spdx_id":null,"url":null,"node_id":"MDc6TGljZW5zZTA="},"forks":5,"open_issues":9,"watchers":23,"default_branch":"master"}},"base":{"label":"mlswg:master","ref":"master","sha":"2437780914c5d0325f08c53cad79258d8d4aa6b4","user":{"login":"mlswg","id":36107802,"node_id":"MDEyOk9yZ2FuaXphdGlvbjM2MTA3ODAy","avatar_url":"https://avatars3.githubusercontent.com/u/36107802?v=4","gravatar_id":"","url":"https://api.github.com/users/mlswg","html_url":"https://github.com/mlswg","followers_url":"https://api.github.com/users/mlswg/followers","following_url":"https://api.github.com/users/mlswg/following{/other_user}","gists_url":"https://api.github.com/users/mlswg/gists{/gist_id}","starred_url":"https://api.github.com/users/mlswg/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/mlswg/subscriptions","organizations_url":"https://api.github.com/users/mlswg/orgs","repos_url":"https://api.github.com/users/mlswg/repos","events_url":"https://api.github.com/users/mlswg/events{/privacy}","received_events_url":"https://api.github.com/users/mlswg/received_events","type":"Organization","site_admin":false},"repo":{"id":109873129,"node_id":"MDEwOlJlcG9zaXRvcnkxMDk4NzMxMjk=","name":"mls-protocol","full_name":"mlswg/mls-protocol","owner":{"login":"mlswg","id":36107802,"node_id":"MDEyOk9yZ2FuaXphdGlvbjM2MTA3ODAy","avatar_url":"https://avatars3.githubusercontent.com/u/36107802?v=4","gravatar_id":"","url":"https://api.github.com/users/mlswg","html_url":"https://github.com/mlswg","followers_url":"https://api.github.com/users/mlswg/followers","following_url":"https://api.github.com/users/mlswg/following{/other_user}","gists_url":"https://api.github.com/users/mlswg/gists{/gist_id}","starred_url":"https://api.github.com/users/mlswg/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/mlswg/subscriptions","organizations_url":"https://api.github.com/users/mlswg/orgs","repos_url":"https://api.github.com/users/mlswg/repos","events_url":"https://api.github.com/users/mlswg/events{/privacy}","received_events_url":"https://api.github.com/users/mlswg/received_events","type":"Organization","site_admin":false},"private":false,"html_url":"https://github.com/mlswg/mls-protocol","description":"MLS protocol","fork":false,"url":"https://api.github.com/repos/mlswg/mls-protocol","forks_url":"https://api.github.com/repos/mlswg/mls-protocol/forks","keys_url":"https://api.github.com/repos/mlswg/mls-protocol/keys{/key_id}","collaborators_url":"https://api.github.com/repos/mlswg/mls-protocol/collaborators{/collaborator}","teams_url":"https://api.github.com/repos/mlswg/mls-protocol/teams","hooks_url":"https://api.github.com/repos/mlswg/mls-protocol/hooks","issue_events_url":"https://api.github.com/repos/mlswg/mls-protocol/issues/events{/number}","events_url":"https://api.github.com/repos/mlswg/mls-protocol/events","assignees_url":"https://api.github.com/repos/mlswg/mls-protocol/assignees{/user}","branches_url":"https://api.github.com/repos/mlswg/mls-protocol/branches{/branch}","tags_url":"https://api.github.com/repos/mlswg/mls-protocol/tags","blobs_url":"https://api.github.com/repos/mlswg/mls-protocol/git/blobs{/sha}","git_tags_url":"https://api.github.com/repos/mlswg/mls-protocol/git/tags{/sha}","git_refs_url":"https://api.github.com/repos/mlswg/mls-protocol/git/refs{/sha}","trees_url":"https://api.github.com/repos/mlswg/mls-protocol/git/trees{/sha}","statuses_url":"https://api.github.com/repos/mlswg/mls-protocol/statuses/{sha}","languages_url":"https://api.github.com/repos/mlswg/mls-protocol/languages","stargazers_url":"https://api.github.com/repos/mlswg/mls-protocol/stargazers","contributors_url":"https://api.github.com/repos/mlswg/mls-protocol/contributors","subscribers_url":"https://api.github.com/repos/mlswg/mls-protocol/subscribers","subscription_url":"https://api.github.com/repos/mlswg/mls-protocol/subscription","commits_url":"https://api.github.com/repos/mlswg/mls-protocol/commits{/sha}","git_commits_url":"https://api.github.com/repos/mlswg/mls-protocol/git/commits{/sha}","comments_url":"https://api.github.com/repos/mlswg/mls-protocol/comments{/number}","issue_comment_url":"https://api.github.com/repos/mlswg/mls-protocol/issues/comments{/number}","contents_url":"https://api.github.com/repos/mlswg/mls-protocol/contents/{+path}","compare_url":"https://api.github.com/repos/mlswg/mls-protocol/compare/{base}...{head}","merges_url":"https://api.github.com/repos/mlswg/mls-protocol/merges","archive_url":"https://api.github.com/repos/mlswg/mls-protocol/{archive_format}{/ref}","downloads_url":"https://api.github.com/repos/mlswg/mls-protocol/downloads","issues_url":"https://api.github.com/repos/mlswg/mls-protocol/issues{/number}","pulls_url":"https://api.github.com/repos/mlswg/mls-protocol/pulls{/number}","milestones_url":"https://api.github.com/repos/mlswg/mls-protocol/milestones{/number}","notifications_url":"https://api.github.com/repos/mlswg/mls-protocol/notifications{?since,all,participating}","labels_url":"https://api.github.com/repos/mlswg/mls-protocol/labels{/name}","releases_url":"https://api.github.com/repos/mlswg/mls-protocol/releases{/id}","deployments_url":"https://api.github.com/repos/mlswg/mls-protocol/deployments","created_at":"2017-11-07T18:14:24Z","updated_at":"2018-08-31T21:40:46Z","pushed_at":"2018-08-31T21:40:44Z","git_url":"git://github.com/mlswg/mls-protocol.git","ssh_url":"git@github.com:mlswg/mls-protocol.git","clone_url":"https://github.com/mlswg/mls-protocol.git","svn_url":"https://github.com/mlswg/mls-protocol","homepage":null,"size":337,"stargazers_count":23,"watchers_count":23,"language":"Makefile","has_issues":true,"has_projects":false,"has_downloads":true,"has_wiki":true,"has_pages":false,"forks_count":5,"mirror_url":null,"archived":false,"open_issues_count":9,"license":{"key":"other","name":"Other","spdx_id":null,"url":null,"node_id":"MDc6TGljZW5zZTA="},"forks":5,"open_issues":9,"watchers":23,"default_branch":"master"}},"_links":{"self":{"href":"https://api.github.com/repos/mlswg/mls-protocol/pulls/54"},"html":{"href":"https://github.com/mlswg/mls-protocol/pull/54"},"issue":{"href":"https://api.github.com/repos/mlswg/mls-protocol/issues/54"},"comments":{"href":"https://api.github.com/repos/mlswg/mls-protocol/issues/54/comments"},"review_comments":{"href":"https://api.github.com/repos/mlswg/mls-protocol/pulls/54/comments"},"review_comment":{"href":"https://api.github.com/repos/mlswg/mls-protocol/pulls/comments{/number}"},"commits":{"href":"https://api.github.com/repos/mlswg/mls-protocol/pulls/54/commits"},"statuses":{"href":"https://api.github.com/repos/mlswg/mls-protocol/statuses/234897d64d47590b298e44343c23b623ec4f4c78"}},"author_association":"MEMBER"}}
{"actor":{"display_login":"ekr"}}