cli/reply: ensure encrypted Subject: line does not leak in the clear

Now that we can decrypt headers, we want to make sure that clients
using "notmuch reply" to prepare a reply don't leak cleartext in their
subject lines.  In particular, the ["reply-headers"]["Subject"] should
by default show the external Subject.

A replying MUA that intends to protect the Subject line should show
the user the Subject from ["original"]["headers"]["Subject"] instead
of using ["reply-headers"]["Subject"].

This minor asymmetry with "notmuch show" is intentional.  While both
tools always render the cleartext subject line when they know it (in
["headers"]["Subject"] for "notmuch show" and in
["original"]["headers"]["Subject"] for "notmuch reply"), "notmuch
reply" should never leak something that should stay under encrypted
cover in "reply-headers".

Signed-off-by: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
This commit is contained in:
Daniel Kahn Gillmor 2019-05-26 18:16:02 -04:00 committed by David Bremner
parent 996ef5710c
commit b7b553e732

View file

@ -76,4 +76,11 @@ output=$(notmuch show --verify --format=json id:signed-protected-header@crypto.n
test_json_nodes <<<"$output" \
'crypto:[0][0][0]["crypto"]={"signed": {"status": [{"created": 1525350527, "fingerprint": "'$FINGERPRINT'", "userid": "'"$SELF_USERID"'", "status": "good"}], "headers": ["Subject"]}}'
test_begin_subtest "protected subject does not leak by default in replies"
output=$(notmuch reply --decrypt=true --format=json id:protected-header@crypto.notmuchmail.org)
test_json_nodes <<<"$output" \
'crypto:["original"]["crypto"]={"decrypted": {"status": "full", "header-mask": {"Subject": "Subject Unavailable"}}}' \
'subject:["original"]["headers"]["Subject"]="This is a protected header"' \
'reply-subject:["reply-headers"]["Subject"]="Re: Subject Unavailable"'
test_done