What is email encryption, and how does it work?

What is email encryption?

Email encryption is a process of converting the text of your email messages from readable plain text into unreadable cipher text. Encryption ensures that even if someone unauthorized intercepts an email, they won’t understand its contents. Only the intended recipient of the encrypted message has the specific key necessary for decrypting the message.

You can use email providers that offer email encryption services by default, or you can employ one of the many email encryption service providers, especially if you’re looking for an enterprise-level solution.

How does email encryption work?

Email encryption is a three-step process. First, when you send an email, the encryption software uses a key to transform your readable message into coded text. Then, the encrypted email travels over the internet, secure from prying eyes. Lastly, the recipient gets your email, and their software uses a corresponding key to decode the scrambled text back into the original, readable message.

The process of securing email communications relies on two main components — public key cryptography and digital signatures:

• Public key cryptography, also known as asymmetric cryptography, involves two encryption keys — a public key and a private key. The sender uses a public key to encrypt the message, while the recipient uses a confidential private key to decrypt the message. Each private key corresponds to one public key and cannot be derived from the public key, ensuring security.
• Digital signatures help assure the recipient that the email has not been altered in transit and confirms the identity of the sender. The sender generates a digital signature using their private key to sign the message or its hash (a shorter digital fingerprint of the data). The recipient then uses the sender’s public key to verify the signature. If the public key can validate the signature, it confirms that the signature was created with the corresponding private key and that the message hasn’t been tampered with since being signed.

Email encryption can be categorized based on the methods and types of encryption used to secure email communications.

Email encryption methods

End-to-end encryption is the most secure email encryption method. It encrypts messages from the sender’s device before they’re sent out, and they remain encrypted until the recipient decrypts them. End-to-end encryption ensures confidentiality because no intermediary, not even the internet service provider (ISP), can decrypt messages and read them.

In-transit encryption, also known as transport layer encryption, encrypts emails as they travel from the sender’s email server to the recipient’s email server using protocols like TLS (Transport Layer Security). In-transit encryption protects the emails from being intercepted while they move across the internet. However, the emails are decrypted on the recipient’s server before being delivered to the recipient’s device. This means the ISPs can access the content of your emails, if needed.

Email encryption types

S/MIME (Secure/Multipurpose Internet Mail Extensions) is widely used in corporate environments to ensure message integrity, authentication, and encryption. S/MIME provides both encryption and digital signatures. This type of email encryption requires that both the sender and receiver have an S/MIME certificate issued by a Certificate Authority (CA). Both parties need to use an email client that supports S/MIME, and they must exchange their certificates beforehand.

PGP/GPG (Pretty Good Privacy/GNU Privacy Guard) also provides a method for encrypting and digitally signing email communications. It’s popular for personal and non-enterprise uses.

PGP/GPG provides a high degree of control over encryption settings and key management, so you can generate your keys yourself. However, the setup and daily use is quite complex, and both sender and recipient must use compatible software.

Some email providers offer built-in encryption that automatically encrypts emails either at rest or in transit, or both. For example, Gmail uses a built-in Transport Layer Security (TLS) cryptographic protocol to encrypt emails during transit between Gmail servers and other servers that support TLS encryption. However, TLS is not as strong as end-to-end encryption, so you might want to learn how to encrypt Gmail to secure your emails.

Email providers that offer built-in email encryption typically utilize one of the three common encryption protocols – SSL, TLS, and STARTTLS. The Secure Sockets Layer (SSL) was the original protocol used for email encryption but was replaced by a more secure and advanced TLS, which is now the standard protocol for sending encrypted messages over email. This brings us to STARTTLS — not a standalone protocol but a way to upgrade an existing, plaintext connection to a secured one using TLS.

Why is email encryption important?

Email encryption is important if you send personal, financial, or sensitive information, or intellectual property via email because it protects your communications from unauthorized access.

In a corporate setting, encryption helps your organization to comply with privacy laws and regulations. Encrypted emails also safeguard against potential internal threats, such as employees who might have access to sensitive communications not meant for them.

With phishing attacks on the rise, encryption serves as a first line of defense, verifying authenticity of communication and reducing the risk of scams. Encryption ensures that you receive secure messages from who they claim to be from, not from scammers trying to trick you.

Should I encrypt my emails?

Yes, you should encrypt your emails if you deal with any sensitive or confidential information or if online privacy is highly important for you. However, for everyday, non-sensitive communications, email encryption isn’t that necessary.

To add an extra layer of security to all your online communications, consider using advanced VPN encryption. A VPN encrypts all internet traffic, including emails, from your device, regardless of the email service you’re using. It’s especially useful for protecting your online traffic when you’re using public Wi-Fi networks, which are often less secure and more susceptible to interception.

For extra privacy, consider using email encryption with an anonymous email account. These accounts allow you to send and receive emails without revealing your true identity or personal information.