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27b25e45dc
Enigmail generates a "legacy-display" part when it sends encrypted mail with a protected Subject: header. This part is intended to display the Subject for mail user agents that are capable of decryption, but do not know how to deal with embedded protected headers. This part is the first child of a two-part multipart/mixed cryptographic payload within a cryptographic envelope that includes encryption (that is, it is not just a cleartext signed message). It uses Content-Type: text/rfc822-headers. That is: A └┬╴multipart/encrypted B ├─╴application/pgp-encrypted C └┬╴application/octet-stream * ╤ <decryption> D └┬╴multipart/mixed; protected-headers=v1 (cryptographic payload) E ├─╴text/rfc822-headers; protected-headers=v1 (legacy-display part) F └─╴… (actual message body) In discussions with jrollins, i've come to the conclusion that a legacy-display part should be stripped entirely from "notmuch show" and "notmuch reply" now that these tools can understand and interpret protected headers. You can tell when a message part is a protected header part this way: * is the payload (D) multipart/mixed with exactly two children? * is its first child (E) Content-Type: text/rfc822-headers? * does the first child (E) have the property protected-headers=v1? * do all the headers in the body of the first child (E) match the protected headers in the payload part (D) itself? If this is the case, and we already know how to deal with the protected header, then there is no reason to try to render the legacy-display part itself for the user. Furthermore, when indexing, if we are indexing properly, we should avoid indexing the text in E as part of the message body. 'notmuch reply' is an interesting case: the standard use of 'notmuch reply' will end up omitting all mention of protected Subject:. The right fix is for the replying MUA to be able to protect its headers, and for it to set them appropriately based on headers found in the original message. If a replying MUA is unable to protect headers, but still wants the user to be able to see the original header, a replying MUA that notices that the original message's subject differs from the proposed reply subject may choose to include the original's subject in the quoted/attributed text. (this would be a stopgap measure; it's not even clear that there is user demand for it) This test suite change indicates what we want to happen for this case (the tests are currently broken), and includes three additional TODO suggestions of subtle cases for anyone who wants to flesh out the test suite even further. (i believe all these cases should be already fixed by the rest of this series, but haven't had time to write the tests for the unusual cases) Signed-off-by: Daniel Kahn Gillmor <dkg@fifthhorseman.net> |
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| .. | ||
| double-wrapped-with-phony-protected-header.eml | ||
| encrypted-message-with-forwarded-attachment.eml | ||
| encrypted-signed-not-masked.eml | ||
| encrypted-signed.eml | ||
| misplaced-protected-header.eml | ||
| nested-rfc822-message.eml | ||
| no-protected-header-attribute.eml | ||
| phony-protected-header-bad-encryption.eml | ||
| protected-header.eml | ||
| protected-with-legacy-display.eml | ||
| signed-protected-header.eml | ||
| simple-signed-mail.eml | ||
| subjectless-protected-header.eml | ||
| wrapped-protected-header.eml | ||