extension ExtPose

FossaGuard: Encrypt Gmail with S/MIME

Description from extension meta

Fossa Guard enables end-to-end S/MIME encryption on top of Gmail® complementing it with industry standard privacy

Image from store FossaGuard: Encrypt Gmail with S/MIME
Description from store Secure e-mailing with Gmail becomes easy on Desktop and Android. Encrypt and Sign your Gmail messages with industry standard - S/MIME using Chrome, Yandex or Firefox browsers. Fossa Server and Fossa Guard web extension provide secure mailing solution on top of Gmail (TM) following S/MIME specification. Fossa Guard generates key pair within your browser then Fossa Server securely supplies you with personal X.509 certificate upon Certificate Signing Request (CSR) so that your private key always stays with you. Use Fossa Guard extension to sign or to encrypt your email with X.509 certificate. The certificate is free and stays valid for 3 months (beta phase limitation). Fossa Guard has own autonomous Compose dialog to avoid unsecured email content auto-saving. Your private key is protected by pass-phrase and is replicated alongside with trusted certificates via your protected local user storage. Use Fossa Guard to get details on certificates in your repository. Please refer to Privacy policy at https://fossa.me/policy

Latest reviews

  • (2018-07-28) Nathan Kaiser: it just doesn't work. It's just too complicated. Tried this, tried that, free version, paid - it would just never work, always something new coming up. Not mature yet.
  • (2018-04-12) Marco Uras: beim schreiben der Empfänger-Email ploppt nur kurz ein Fenster auf um das Konto auszuwählen. So kann man keine Mail schreiben.
  • (2017-11-01) William Stewart: I had high hopes for this but entering email addresses by hand (instead of them popping up as they do in Gmail) was an issue, complicated by the email address always showing one less letter than I actually typed. That was quite annoying. ***UPDATE: This aspect suddenly started working properly after exiting my browser and restarting it, and logging in to Chrome again. *** I then attempted to send an email from within the extension, and it warned me that it would be sent unencrypted and asked me if I wanted to continue. I chose to continue but it then failed telling me that the recipient wasn't secure (diff wording). So it could not even send an email out insecurely. This has proven to be frustrating and a waste of my time. Too bad.
  • (2017-03-29) Ariel Sandberg-Maitland: This is a great start. Just playing with it for a bit and I was able to send smime encrypted between my work and gmail email. Needed to figure out how to add my work smime cert as a trusted endpoint. I see I have a fossa smime cert in my windows key store. I will see what happens later when trying to setup on a different computer. I suppose I could backup and import my fossa smime cert. Great Job. This is pretty good. I don't think there is much out there like this. Keep up the great work!
  • (2017-02-09) Did not work. Perhaps because I was using gmail to read emails of different account? idk. Regardless even after installing smime.p7m is still attached and I can't view even after installing the extension.
  • (2016-11-27) Stanton McCandlish: Nice start, but three-month certs and 100KB max attachment size doesn't cut it, nor does the Fossa window closing itself if you type your passphrase wrong even one time. I look forward to giving this 5 stars after it's out of beta and such issues are ironed out. I'm impressed by the seamless integration.
  • (2016-09-23) Michał Patrzałek: Is there a way to make this extension work in Opera?
  • (2016-08-02) Maxim Sokolov: It works! Finally I've got free S/MIME implementation for GMail with attachments support.
  • (2016-08-01) Marcel Schnirring: Finally a S/MIME solution for Gmail in Chrome! I am looking forward to add the possibility to use own certificates! Further, I couldn't find a way to verify signatures from Emails I receive... Keep on with your work, there are many people waiting for it!

Latest issues

  • (2019-02-07, v:0.4.3) Murat Bugan: About Fossaguard
    Hi, I installed the Fossaguard plugin. But when it comes to digitally signed e-mail, I can't open it. When I create a digitally signed mail, I can open it. Should this plugin be installed on both sides? Murat.
  • (2017-11-16, v:0.3.5) Martyn Hanmore: Certificate Storage
    Hi, One of your replies indicates that Certificates are synched when logging into a different Chrome browser. Does that mean private keys are kept in the cloud? If a Google account is compromised then encrypted emails should at least be safe, but cloud Certificate storage would give them to the hacker too... better to make people take proper care of their keys! thanks Martyn
  • (2017-10-30, v:0.3.5) Ricky Souza: Level of Encryption
    What is the encryption bit level?
  • (2017-08-09, v:0.3.4) Brian Dixon: Unable to access Extension Options Page in Chrome
    Hello! I've tried installing the Fossa Guard Chrome extension on a Win10 Enterprise and MacOS Sierra platform, and in both instances I am unable to open the Options page for the Fossa Guard extension.. and I'm not certain how I am supposed to configure your product, if I can't get to the Options/Config page. Win10 is running Chrome Version 60.0.3112.90 (Official Build) (64-bit), and MacOS is running Version 59.0.3071.115 (Official Build) (64-bit). I'm not seeing anything published about this sort of issue.. so any help would be very much appreciated! Thank you, --Brian
  • (2017-05-30, v:0.3.3) Search through encrypted mails
    Will I be able to search through the encrypted mail I received/sent?
  • (2017-04-17, v:0.3.3) Krissy C: Will this work for OWA on Chrome?
    Hello, I need to view an e-mail on an OWA server (not gmail) that was encrypted. Will this extension work outside of gmail? Thank you.
  • (2017-03-31, v:0.3.3) Marvin Lindsay: Shared Secret
    How do you generate a new Shared Secret?
  • (2017-03-29, v:0.3.3) Ariel Sandberg-Maitland: Decrypting Email
    Prompts me for my Key Pass. I click done and it does nothing... I have added Endpoint & their Root CA's and Sub Ca's as trusted.
  • (2017-03-29, v:0.3.3) Ariel Sandberg-Maitland: When replying to, stuck at parsing...
    Trying to reply to a signed email. and it is stuck at Parsing... I trusted the Root and Sub Ca of the user's Smime cert. Then I replied. THanks
  • (2017-03-21, v:0.3.3) Vijayashankar Na: Resetting passphrase
    What is the procedure for resetting the passphrase?
  • (2017-03-18, v:0.3.3) Ohad Hershkovitz: using existing keys
    can i import existing keys (e.g. mailvelope) instead of creating and sharing new keys?


897 history
3.0 (12 votes)
Last update / version
2020-01-15 / 0.4.19
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