Email Encryption Before Server: Options & Future Tech

TL;DR

Encrypting email before it reaches your mail server is tricky but possible with end-to-end encryption (E2EE). Standard email protocols don’t do this automatically. Solutions like PGP/GPG and newer standards like E2EE extensions for existing protocols are available, though they have usability challenges. Emerging technologies aim to simplify this process.

Can Email Be Encrypted Before It Reaches the Mail Server?

Normally, when you send an email, it travels in plain text (or with basic TLS encryption) between your computer and your mail server, then from your server to the recipient’s server. This means anyone controlling those servers could potentially read your message. Encrypting before sending to the server adds a layer of security.

How to Encrypt Email Before Server Access

1. End-to-End Encryption (E2EE): This is the key concept. E2EE ensures only you and the recipient can decrypt the message, even if servers are compromised.
2. PGP/GPG: Traditionally, Pretty Good Privacy (PGP) or GNU Privacy Guard (GPG) have been used for E2EE. They work by using public and private key pairs.
   • Key Generation: You generate a pair of keys – a public key you share with others, and a private key you keep secret.
   • Encryption Process: When someone wants to send you an encrypted email, they use your public key to encrypt it.
   • Decryption Process: You decrypt the message using your private key.

   Example of encrypting with GPG:

   gpg --encrypt --recipient [email protected] myfile.txt

   This creates a file (myfile.txt.gpg) that only the recipient with the corresponding private key can decrypt.

3. S/MIME: Similar to PGP/GPG, but relies on X.509 certificates issued by Certificate Authorities. It’s often used in corporate environments.
4. Email Clients with Built-in E2EE: Some email clients (like ProtonMail, Tutanota) offer E2EE by default. These services handle the encryption/decryption process for you.
   • ProtonMail: Emails are encrypted on your device before being sent to their servers and decrypted only on the recipient’s device if they also use ProtonMail.
   • Tutanota: Similar functionality to ProtonMail, focusing on privacy and security.
5. E2EE Extensions (e.g., STARTTLS with E2EE): Newer standards are being developed to add E2EE capabilities to existing email protocols like SMTP.
   • These extensions aim to make E2EE more seamless and compatible with standard email clients without requiring PGP/GPG setup.
   • Implementation is still ongoing, so support isn’t widespread yet.

Challenges with Current Solutions

• Complexity: PGP/GPG can be difficult to set up and use for non-technical users (key management is a major hurdle).
• Key Exchange: Securely exchanging public keys is crucial. Compromised keys render encryption useless.
• Compatibility: Not all email clients support PGP/GPG or S/MIME, leading to interoperability issues.
• Metadata: E2EE typically only encrypts the message content, not metadata (sender, recipient, subject line).

What’s Being Worked On?

1. Autocrypt: Aims to automate PGP key exchange and simplify encryption within standard email clients.
2. MLS (Messaging Layer Security): A relatively new protocol designed for E2EE in messaging apps, but adaptable to email. It focuses on group messaging security and is gaining traction.
   • It’s more modern than PGP/GPG and aims to address some of its usability issues.
3. Improved Email Client Support: Major email providers are starting to explore integrating E2EE features directly into their clients, making it easier for users.

Conclusion

While encrypting email before server access isn’t the default, it’s achievable with tools like PGP/GPG and services like ProtonMail. Ongoing development of standards like MLS and Autocrypt promises to make E2EE more accessible and widespread in the future, improving cyber security for everyone.