1737294 - multipart messages signed with S/MIME are show invalid in Outlook

Status: RESOLVED DUPLICATE of bug 1731529

(MailNews Core :: Security: S/MIME, defect)

Description

[thomas]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:93.0) Gecko/20100101 Firefox/93.0

Steps to reproduce:

only in thunderbird 91.2.0(64-bit), (does not happen in thunderbirt 78.13.0 (32-bit))

• compose email, content "hello groegert", subject "hello"
• select Menu->Options->Delivery Format->Plain and Rich (HTML) Text
• select Menu->Options->Encryption Technology->S/MIME
• select Menu->Options->Digitaly Sign This Message
• send

Actual results:

• outlook shows an invalid signature

Expected results:

• outlook shows a correct signature

Comment 1

[thomas]

may be bug# 1646404 is related to this bug.

comparing messages sent by thunderbird 78.13 and thunderbird 91.2 are showing an additional newline thunderbird 91.2 right before the multipart separator.

thunderbird itself shows a correct signature.

Comment 2

[peet1993]

Attachment: Thunderbird 78 - Both Plain and HTML in body

Comment 3

[peet1993]

Attachment: Thunderbird 78 - Plain body + attachment

Comment 4

[peet1993]

Attachment: Thunderbird 91 - Both Plain and HTML in body

Comment 5

[peet1993]

Attachment: Thunderbird 91 - Plain body + attachment

Comment 6

[peet1993]

We also noticed this happening in our environment.
I can confirm that Outlook shows an invalid signature when sending both a plain and HTML version in the same mail, i.e. a multipart message.
It also happens with multipart messages constructed from a plain message and an attachment.

I attached test mails from both TB 78 and 91 from Linux, once with Plain+HTML and once with Plain+Attachment. The 91 variants show an invalid signature in outlook. I hope they help out during debugging.
The main differences between the two versions I can spot is a missing "This is a multi-part message in MIME format." line above the first multipart separator in TB 91 and the use of 7bit as Content-Transfer-Encoding in TB 91 over quoted-printable in TB 78.

Comment 7

[peet1993]

Attachment: Thunderbird 91 - Both Plain and HTML in body

Comment 8

[peet1993]

I updated the Attachment "Thunderbird 91 - Both Plain and HTML in body" as it contained modifications from the original file. Sorry about that.

Comment 9

[peet1993]

Attachment: Thunderbird 91 - Both Plain and HTML in body - Version from sent folder.

I found another potential hint with the help of colleagues:
For the mixed content version, the Mail stored in the sent folder differs from the received version, it contains an additional line break in the HTML part.

The received mail still verifies successfully in Apple Mail, Thunderbird 78 / 91 and openssl.

Comment 10

[peet1993]

This is a duplicate of bug 1731529.
I can confirm that my examples show the same behaviour as mentioned in bug 1731529, comment 8.