On Feb 19, 2016, at 2:18 PM, Paul Wouters <paul(_at_)nohats(_dot_)ca> wrote:
I do not understand how the process of a plaintext email that goes
through this document's advice, and leaves as either still plaintext
or encrypted, could be construed as a "cryptographic downgrade".
RFC7435 has not been read attentively, or perhaps is viewed as heresy:
https://tools.ietf.org/html/rfc7435#section-1.2
"Opportunistic Security" (OS) is defined as the use of cleartext as
the baseline communication security policy, with encryption and
authentication negotiated and applied to the communication when
available.
Cleartext, not comprehensive protection, is the default baseline. An
OS protocol is not falling back from comprehensive protection when
that protection is not supported by all peers; rather, OS protocols
aim to use the maximum protection that is available.
--
Viktor.