How does email encryption work?

Since it has become known that the NSA monitors the email traffic of all user accounts, the question of encryption has become increasingly important. In this article we will show you how email encryption works.

Asymmetric email encryption

Unencrypted emails are sent in clear text from the sender to the recipient. An email can be read relatively easily on the way to the recipient. This can be remedied by an encryption procedure that arises from a public key and is decrypted by a private key.

• Software: In order to be able to encrypt and decrypt emails at all, you need software that generates two individual keys. The freeware Gpg4win is suitable for this, for example, which can cryptograph documents using the recipient's public key and decrypt them again.
• Digital signature / certificate: The sender must know the recipient's public key in advance so that he can encrypt the email so that only the recipient can read the message with his private key. The transmission takes place either via a digitally signed email or via a key server.
• Encryption: The recipient's public key is responsible for encrypting the email. With Gpg4win, for example, you copy the email in plain text to the clipboard and encrypt the text by entering the public key of the recipient. You send the resulting text as usual. From now on, only the recipient with his private key will be able to read the email.
• Decryption: The sender now decrypts the email with his private key. He uses either a SmartCard or a password.

Email encryption: short summary

If you use software to encrypt an email, the recipient must use the same software to read the email. If you want to send files, you can encrypt them with a password. Many plugins for your web browser only encrypt the text, but not the files. Furthermore, it is not possible to send emails to several people at once, since everyone has a different private key for decrypting.