Re: [w3c/webcomponents] Generic programs can't reliably use/manipulate documents via the DOM (#640)

> May I add a couple legitimate use cases for hard-private, inaccessible DOM

@isiahmeadows please do

> Guarding an `<input type="username">`/`<input type="password">` from successful script injection and/or malicious extensions.

This is not something the shadow DOM was created for, and it doesn't give any *guarantees* of security. To quote from an [earlier email](https://lists.w3.org/Archives/Public/public-webapps/2014JanMar/0333.html) on the topic:

> > Stay after class and write 100 times on the board: "Type 2 is not a security boundary".

> Currently, all it takes is a single successful XSS attack to literally read a user's password as they type it[...] The only way to stop it at this stage is via CSP policy, and some form of MITM mitigation like TLS

This is also a problem with (session) cookies, etc. A properly set CSP is the way to make these guarantees. If you are MITM-ed, game over anyway.

Shadow DOM may help in this way, but it's not the intention of the design, and I don't think it's a good argument for closed shadow DOMs.

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