Subject: [Uta] fyi: Using HSTS in Conjunction with Self-Signed Public-Key Certificates

From: =JeffH <[email-masked]>
Date: Mon, 23 Mar 2015 14:02:36 -0700

Using HSTS in Conjunction with Self-Signed Public-Key  Certificates
https://tools.ietf.org/html/rfc6797#section-11.3

11.3. Using HSTS in Conjunction with Self-Signed Public-Key

Certificates

    If all four of the following conditions are true...

    o  a web site/organization/enterprise is generating its own secure
       transport public-key certificates for web sites, and

    o  that organization's root certification authority (CA) certificate
       is not typically embedded by default in browser and/or operating
       system CA certificate stores, and

    o  HSTS Policy is enabled on a host identifying itself using a
       certificate signed by the organization's CA (i.e., a "self-signed
       certificate"), and

    o  this certificate does not match a usable TLS certificate
       association (as defined by Section 4 of the TLSA protocol
       specification [RFC6698]),

    ...then secure connections to that site will fail, per the HSTS
    design.  This is to protect against various active attacks, as
    discussed above.

    However, if said organization wishes to employ its own CA, and self-
    signed certificates, in concert with HSTS, it can do so by deploying
    its root CA certificate to its users' browsers or operating system CA
    root certificate stores.  It can also, in addition or instead,
    distribute to its users' browsers the end-entity certificate(s) for
    specific hosts.  There are various ways in which this can be
    accomplished (details are out of scope for this specification).  Once
    its root CA certificate is installed in the browsers, it may employ
    HSTS Policy on its site(s).

    Alternatively, that organization can deploy the TLSA protocol; all
    browsers that also use TLSA will then be able to trust the
    certificates identified by usable TLS certificate associations as
    denoted via TLSA.

    NOTE:  Interactively distributing root CA certificates to users,
           e.g., via email, and having the users install them, is
           arguably training the users to be susceptible to a possible
           form of phishing attack.  See Section 14.8 ("Bogus Root CA
           Certificate Phish plus DNS Cache Poisoning Attack").  Thus,
           care should be taken in the manner in which such certificates
           are distributed and installed on users' systems and browsers.