Ian Bell writes:
It would be good if there were an interoperable way of making the
stored, decrypted message reflect the message the author would have
liked to send in the first place. It would be particularly nice if the
author could transmit the intended subject of a message when this may be
too sensitive to put in the open message headers.
The Subject header would be one which would benefit most from encryption.
Subjects leak information about message contents. Used carelessly, they
may expose the meaning of the message, or at least indicate which messages
contain sensitive information that might be targetted by an attacker.
However, replacing the Subject header only when the message is stored
for later reference misses another possible benefit. Many archived
messages are never even referred to again.
What would be even better would be if the user's mail software decrypted
all messages in the incoming mailbox and "promoted" message/rfc822
headers up to the message header level. Then the encrypted message
subjects could be displayed before the messages are read. Busy email
users often use Subject headers to prioritize their mail handling.
But to make use of this capability, decrypted Subject headers must be
presented by the mail software beforehand.
I'd like to see a convention established for interpreting the
message/rfc822 type in this way, possibly when accompanied by some
other syntax.
Hal