Accept also S/MIME keys

Hmm, yes, being able to use S/MIME would be nice, too, but I don’t know of an existing library I can use to do this. I’ll mark this is as an enhancement suggestion on the GitHub project. Thanks, though.

Thanks for accepting the suggestion as valid.

I’m not a programmer, so I don’t know if this may help you achieve the objective or not:
– https://www.ads-software.com/plugins/smime/ some S/MIME plugin, maybe you can inspire in the code.

– https://php.net/manual/en/function.openssl-pkcs7-encrypt.php , https://php.net/manual/en/function.openssl-pkcs7-sign.php and https://php.net/manual/en/openssl.ciphers.php PHP itself supports S/MIME including advanced encryption.

I hope at least one of this may help you, if not, at least I tried =)

?? Thanks for those links.

You’re welcome. I hope they are useful. If not, at least I tried =)

Just a brief update to let you know someone has generously volunteered to take this on.

That is a great news! Thanks to the user willhowells at github for the work.
I hope that eventually you can integrate the code into the plugin after all quality assurance.

@linmp I’ve successfully integrated @willhowells’s work into a development version with support for sending encrypted S/MIME messages. Would you be so kind as to help us test this? I would like it to undergo at least some testing by the people who would use the feature before I release it. (I have almost never used S/MIME before so am not nearly as familiar with it as I am with GnuPG.) If you can help test, please let me know either here or, even better, on the GitHub issue tracking S/MIME support for this project. Thanks!

@linmp Initial S/MIME support has been implemented and released in version 0.6.0, available now. Please give this a try and let me know how it works for you! ??

Hi Meitar!
Thanks to willhowells and you Meitar for adding the support for S/MIME in the 0.6.0 version!

I will test the S/MIME feature in the most recent version 0.6.1 at this time, and I will give the feedback on it soon, about errors or things that can be improved if any.

I have just tested S/MIME (for now) to send a form from web site to the admin e-mail and I find my first problem:

I’ve tested the 0.6.2 and is not working properly for me when I received the messages encrypted to the admin from a contact form.

I have found why it didn’t properly decrypts in the e-mail software, your software is sending the e-mail with the following before the encrypted content:

============= BEGIN =============
X-WPCF7-Content-Type: text/plain
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8

MIME-Version: 1.0
Content-Disposition: attachment; filename=”smime.p7m”
Content-Type: application/x-pkcs7-mime; smime-type=enveloped-data; name=”smime.p7m”
Content-Transfer-Encoding: base64
============= END =============

I have change this to:

============= BEGIN =============
X-WPCF7-Content-Type: text/plain
MIME-Version: 1.0
Content-Disposition: attachment; filename=”smime.p7m”
Content-Type: application/x-pkcs7-mime; smime-type=enveloped-data; name=”smime.p7m”
Content-Transfer-Encoding: base64
============= END =============

And the message was properly open.

The problem is with the string:

Content-Type: text/plain; charset=UTF-8

If it is removed from there, the message opens properly.
I will continue testing after this is corrected.

Thanks for testing this. Can you please post the full source of the email (both original and corrected) so I can see a complete example? Thanks. ??

Yes, first the sample that is send that doesn’t work:

======================== SAMPLE-NOT-WORKING.eml : BEGINNING ========================

Return-Path: <[email protected]>
X-Original-To: [email protected]
Delivered-To: [email protected]
From: Carla Ariana <[email protected]>
To: [email protected]
Subject: Blogmania “Acerca daquilo”
Date: Fri, 26 May 2017 15:08:33 +0000
Reply-To: [email protected]
X-Mailer: PHPMailer 5.2.22 (https://github.com/PHPMailer/PHPMailer)
X-WPCF7-Content-Type: text/plain
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8

MIME-Version: 1.0
Content-Disposition: attachment; filename=”smime.p7m”
Content-Type: application/x-pkcs7-mime; smime-type=enveloped-data; name=”smime.p7m”
Content-Transfer-Encoding: base64
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======================== SAMPLE-NOT-WORKING.eml : END ========================

Based on the sample above send to me I did the change bellow that makes it work on the e-mail program:

======================== SAMPLE-WORKING.eml : BEGINNING ========================

Return-Path: <[email protected]>
X-Original-To: [email protected]
Delivered-To: [email protected]
From: Carla Ariana <[email protected]>
To: [email protected]
Subject: Blogmania “Acerca daquilo”
Date: Fri, 26 May 2017 15:08:33 +0000
Reply-To: [email protected]
X-Mailer: PHPMailer 5.2.22 (https://github.com/PHPMailer/PHPMailer)
X-WPCF7-Content-Type: text/plain
MIME-Version: 1.0
Content-Disposition: attachment; filename=”smime.p7m”
Content-Type: application/x-pkcs7-mime; smime-type=enveloped-data; name=”smime.p7m”
Content-Transfer-Encoding: base64
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======================== SAMPLE-WORKING.eml : END ========================

Hmm, that doesn’t look like the emails my test site is producing. Can you confirm if you are using a plugin as well? Maybe Contact Form 7?

I confirmed this is a problem with Contact Form 7 and that without that plugin (i.e., the built-in WordPress email sending) the S/MIME encryption and decryption succeeds. I’m not totally sure yet if the incompatibility with Contact Form 7 is something I can fix on my side, or if I need to to submit a patch Contact Form 7 to make it play nice with encrypted emails. I will report back when I have more details.

@linmp I have released version 0.6.3 which fixes the incompatibility with Contact Form 7 in my testing. The issue was caused by superfluous newlines that were added by Contact Form 7, causing the various emailing routines to handle some header lines as though they were body lines. This has been fixed on my end without needing a patch for the Contact Form 7 upstream by more rigorously checking and filtering out any empty header lines, which means this fix should work reliably forever. ??

Please let me know how this works for you. Thanks again for your help testing it out!