Paranoid Email: End-to-End Encryption Primer

Over the previous decade, Twilio SendGrid has embraced Transport Layer Security (TLS) encryption as a technique to defend outbound emails as these journey between servers.

In a digital world rife with cyberattacks, implementing true end-to-end electronic mail encryption for delicate emails has turn out to be more and more crucial.

However what precisely does this imply? This submit gives an summary of what end-to-end encryption is and the sorts of surveillance it protects customers from.

Bulk vs. focused surveillance

Simple Mail Transfer Protocol (SMTP) with TLS protects “information in movement.” So if you submit an electronic mail to SendGrid utilizing TLS, we encrypt it because it travels out of your mail server to our mail servers. We then try and ship it to your recipients over a TLS-encrypted connection. If their mail server helps TLS, we’ll ship an encrypted model of your electronic mail, guaranteeing that passive surveillance gadgets will solely see ciphertext.

This technique is efficient towards passive bulk surveillance methods—just like the National Security Agency tap at AT&T’s backbone facility. Nonetheless, a decided attacker who has the technical means might carry out a focused “man in the middle” attack on the TLS connection. With their very own certificates and key, the hacker can decrypt the ciphertext and seize the content material earlier than reencrypting it and forwarding it to the authentic vacation spot server.

As cyber attackers proceed to evolve their strategies, it’s essential to develop options that counter their extra aggressive approaches—whether or not by means of Java-encrypted electronic mail or different methods. 

Finish-to-end electronic mail encryption

To defeat energetic assaults towards SSL and TLS, customers can implement end-to-end or “information at relaxation” electronic mail encryption utilizing languages like PHP or Java. 

Public key encryption options for electronic mail have been round for the reason that Nineteen Nineties. The primary profitable implementation was Fairly Good Privateness (PGP), created by Boulderite Phil Zimmerman again in 1991. 

PGP was the focus of the crypto wars (that’s quick for “encryption,” not “cryptocurrency”). At one level, Zimmerman famously printed the supply code as a hardback e-book by way of MIT press and distributed it below First Modification protections. Nonetheless, PGP by no means actually noticed industrial success, maybe as a result of the expertise was too hard to use. GNU Privacy Guard (GPG) is a substitute for PGP obtainable below Common Public License.

One other kind of end-to-end encryption is Safe/Multipurpose Web Mail Extensions (S/MIME), a typical for public key encryption developed in 2004. S/MIME leverages X.509 certificates as an alternative of PGP keys. Whereas comparatively obscure, common mail purchasers like Outlook, Mail.app, and Thunderbird have supported it for years—so long as you’ve got the best third-party plugins put in, that’s. Apple has additionally supported S/MIME encrypted electronic mail on iPhones/iPads since 2012, with the discharge of iOS 5.

One main critique of S/MIME is that its safety mannequin relies on trusting public certificates authorities, which have suffered severe compromises that undermine the entire system. Actually, the general public key infrastructure (PKI) on which the complete web relies upon is barely as robust as its weakest hyperlink.

Though this matter might transcend the scope of this weblog submit, it’s essential to notice your browser relies on the general public PKI. So, for most individuals, S/MIME and publicly trusted certificates ought to present affordable safety. 

For those who imagine that you’re topic to focused surveillance and wish end-to-end electronic mail encryption, you’ll be able to nonetheless realistically use S/MIME with self-signed certificates. Nonetheless, you need to confirm the certificates fingerprints for the events you talk with out of band, similar to you’d confirm PGP key fingerprints.

Learn extra concerning the several types of encryption in our email encryption FAQ.

Google and end-to-end encryption

It’s essential to notice that, regardless of including sections to its Transparency Report to handle electronic mail safety issues, Google doesn’t offer true end-to-end email encryption. Google’s TLS encryption ensures that nobody’s taking a look at your electronic mail en route from level A to level B; nevertheless, it doesn’t assure that the message will stay personal as soon as it reaches the vacation spot server. Actually, Google itself scans your inbox to energy its sensible options and flag suspected spam. 

Moreover, Google solely helps S/MIME encryption if the sender and receiver use paid Google Workspace Suite accounts and trade safety keys throughout preliminary configuration. Whereas Google has talked about end-to-end encryption since 2014, it has made little progress to this point. At the moment, the one technique to get that stage of safety is to depend upon third-party service suppliers to bridge the hole.

Ship safe emails with Twilio SendGrid

Now that a bit about PGP/GPG and S/MIME, which one would you select? As we talked about above, Outlook, Thunderbird, Mail.app, and iPhone/iPad have native help for S/MIME. We will stroll you thru the setup course of in our submit, End-To-End Encryption with S/MIME. 

To study extra about securing your outbound emails, try How to Send a Secure Email for Access and Delivery. For those who’re prepared to begin sending safe emails, try SendGrid for free.