Change:
Alice is logged onto the calling service and decides to call Bob. She can see from the calling service that he is online and the calling service presents a JS UI in the form of a button next to <del> Bob's name which says "Call".  Alice clicks the button, which </del> <ins> Bob's name that says "Call".  Alice clicks the button, which </ins> initiates a JS callback that instantiates a PeerConnection object. This does not require a security check: JS from any origin is allowed to get this far.

Discussion:
Changes based on .
NAME NAME NAME NAME PTAL Also, there were two I wasn't entirely sure how to address: : "In this case, the established identity SHOULD be applied to existing DTLS connections as well as new connections established using one of those fingerprints." Applied by the recipient? (consider active voice). Also, why not MUST? Don't unexpected things happen if the recipient doesn't do this? : "Because HTTP origins cannot be securely established against network attackers, implementations MUST NOT allow the setting of permanent access permissions for HTTP origins. Implementations MUST refuse all permissions grants for HTTP origins." (nit-ish) - The MUST NOT seems non-constraining considering the last sentence. Or am I reading that sentence wrong?
case, the established identity can be attributed to existing DTLS connections with fingerprints that match any of the included fingerprints, plus any new connections established using one of those fingerprints. This doesn't need a SHOULD, it's axiomatic. The 6.2 thing is a interesting. The second statement appears to be merely a restatement of the first, for emphasis, but it is a stronger statement. So Ben is right, the first sentence is unnecessary. attackers, implementations MUST refuse all requests for permission grants from HTTP origins.
NAME okay fixed these points. On to Ben K's.
I don't think this "SHOULD" -> "can" for identities is right. Actually, I think it needs to be a MUST.
This won't build, but it looks fine otherwise. Ben Campbell has entered the following ballot position for draft-ietf-rtcweb-security-arch-18: Yes When responding, please keep the subject line intact and reply to all email addresses included in the To and CC lines. (Feel free to cut this introductory paragraph, however.) Please refer to URL for more information about IESG DISCUSS and COMMENT positions. The document, along with other ballot positions, can be found here: URL COMMENT: Update: Ignore my comment about t= vs c=0. I had my order crossed; it is correct in the example. I'm balloting "yes", but have a few minor comments and editorial comments: : (nit) The first sentence will not age well; I gather RTCWEB will close before long. (also The WG acronym is RTCWEB, not WebRTC.

Or are you talking about the W3C?) (nit) Figure 2: It seems a bit weird to have XMPP here, but never mentioned in the text. At least, please expand the abbreviation somwhere. (It also shows up in figure 4.) (nit) §3.1, first bullet: While I don't normally object (beyond nose holding, anyway) to the use of first person in RFCs, it seems an odd choice for this sentence. I assume "we" in this sentence does not refer to the the author or the WG. : (nit) - '... button next to Bob’s name which says "Call".': s/which/that "The calling site will also provide some user interface element (e.g., a button) to allow Bob to answer the call, though this is most likely not part of the trusted UI." This is the first mention of "trusted UI". It would be helpful to elaborate on that prior to this mention. : "In this case, the established identity SHOULD be applied to existing DTLS connections as well as new connections established using one of those fingerprints." Applied by the recipient? (consider active voice). Also, why not MUST? Don't unexpected things happen if the recipient doesn't do this? : "Because HTTP origins cannot be securely established against network attackers, implementations MUST NOT allow the setting of permanent access permissions for HTTP origins. Implementations MUST refuse all permissions grants for HTTP origins." (nit-ish) - The MUST NOT seems non-constraining considering the last sentence. Or am I reading that sentence wrong? (nit) - .E.g., "Call EMAIL"' : sentence fragment. (nit) - ".. unlikely that browsers would have an X.509 certificate..." : Plural disagreement (assuming the browsers do not share 1 cert). (maybe nit) - "Clients MAY permit the formation of data channels without any direct user approval." Is the switch from talking about "the browser" to "Clients" intentional? : (nit) - "Note that these requirements are NOT intended..." "NOT" in all caps is likely to be confused with 2119/8174 language. : (nit) - "Implementations MUST implement SRTP [RFC3711].

Implementations MUST implement DTLS [RFC6347] and DTLS-SRTP [RFC5763][RFC5764] for SRTP keying. Implementations MUST implement [RFC8261]." Thank you for using the citation style that doesn't assume everyone has memorized the RFC numbers. But why not do the same for 8261? : (nit) - First paragraph: Can there be a citation for the W3C API spec? (My bad, the draft is correct. Comment removed.) §7.1.4, SDP example: (nit) §11: The first sentence is a fragment. (normative references) (nit) - There's a reference to RFC 5234, but it is not cited in the text. Is there a reason to reference 5246 rather than 8446, which obsoleted it? : seems like the jsep reference should be normative.