Encrypted Email

Email encryption is a crucial measure for securing email communications, especially when dealing with sensitive or confidential information. What are the security options?

Introduction

Email encryption is the process of encoding email messages to ensure their content remains secure and can only be read by the intended recipient. It protects emails from unauthorized access and tampering during transmission.

Benefits of Email Encryption:

1. Ensures confidentiality, preventing unauthorized access.
2. Maintains message integrity, ensuring the email isn't altered during transmission.
3. Provides authentication by verifying the sender's identity through digital signatures.

How Email Encryption Works:

1. Encryption: Converts plaintext (readable email content) into ciphertext (encoded content) using encryption algorithms. Requires a key to decrypt the content back into its original form.

2. Decryption: The recipient uses a corresponding key to decode the email and view its contents.

Methods of Email Encryption

1. Transport-Level Encryption

Protects the message while it is in transit between servers or email clients.

The most widely used protocol today is TLS (Transport Layer Security):

• Encrypts emails between mail servers to prevent interception.
• The user does not have to set anything up, everything is arranged by their email service provider.
• From a user's perspective, it is sometimes difficult to check and be sure that the service provider is really using encryption when transmitting messages between servers.
• Limitation: The email is decrypted on the recipient's server, making it readable to anyone who has access to the server.

2. End-to-End Encryption

Secures the message from sender to recipient, ensuring it is encrypted throughout the entire process.

Popular end-to-end encryption standards:

• S/MIME (Secure/Multipurpose Internet Mail Extensions): Uses X.509 certificates for encryption and signing. Setup is relatively easy and therefore we recommend this method, which is described below.
• PGP (Pretty Good Privacy): Allows users to encrypt and sign emails using public/private key pairs. Too complicated setup for both sender and recipient

S/MIME Email Encryption

Secure/Multipurpose Internet Mail Extensions (S/MIME) is a standard for securing email communication using encryption and digital signatures.

Advantages of S/MIME:

1. Strong encryption and authentication methods.
2. Broad support across enterprise and personal email systems.
3. Automatic integration with many email platforms.

Requirements for S/MIME:

What you need to be able to start encrypting your emails with S/MIME:

1. Digital Certificates: It is issued for the sender's email address by a trusted certification authority. In addition to the certificate, you are also issued a private key that you will use to encrypt messages when creating them.

   • Certificate issuers: Actalis  (offers free certificates), DigiCert , GlobalSign .

2. Compatible Email Client: Many email clients support S/MIME, such as Mozilla Thunderbird  (free), Microsoft Outlook  a Apple Mail .

3. Key and Certificate Management: User must store their private key securely and protect it from theft. The issued certificates have a limited validity, usually one year. Therefore, they must be renewed before expiration.

Challenges:

1. Complexity: End-to-end encryption requires setup of keys or certificates, which can be complex for non-technical users.
2. Compatibility: Both the sender and recipient must use compatible software that supports encryption and S/MIME.
3. Cost: Some encryption solutions require paid certificates or enterprise tools.

Secure Email Providers

Some email service providers offer end-to-end encryption within their platform, eliminating the need for an S/MIME certificate and additional configuration.

• ProtonMail : End-to-end encrypted email service.
• Tutanota : Secure email with built-in encryption.

Email Attachment Encryption

If it is not possible to encrypt the content of the email, it is advisable to encrypt at least the attachment if it contains sensitive data.

Users can manually encrypt attachments by adding a password (e.g., using tools like WinZip , 7-Zip , or Adobe Acrobat  for PDFs). The password must be shared securely with the recipient, typically through a different communication channel.