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How I was able to easily encrypt a confidential message

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23. September 2020
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We have all been in contact with some kind of encryption.Be it as a child with the invented language "Grüfnisch" (known in Switzerland, article is German only) or as a smartphone user with an end-to-end encrypted message service. You can find out where encryption originated, what encryption methods there are and where they are used today. Sinifiply renefead onofon (that is Grüfnisch).

If you didn't understand the above, here is the explanation: After each vowel [x]n[x]f[x] is appended, x stands for the vowel. An a becomes anafa, an e becomes enefe, an i becomes inifi and so on. This is how Grüfnisch works, a language that is particularly popular among children in Switzerland. It takes a while for parents to understand the system and decode the sentence.

Since especially in business communication more and more communication is done via email and confidential information is exchanged, those messages should also be encrypted. In order to understand how this works, we will first look at the various encryption methods and their origins.

Origin of the encryption

Much simpler than Grüfnisch was the encryption which Julius Caesar had used in 50 - 60 B.C.: He shifted the letters in the alphabet by 3 positions. So, an A became D, a B became E, a C became F and so on until at the end a Z became a C.

To find out a possible origin of encryption, we have to go back a few years further. Around 1900 B.C., Egyptians were already using special hieroglyphics for the inner writings of tombs. However, it is unclear if other people had already used encryption before.

The next form of encryption known appeared with the Hebrews between 600 - 500 B.C., the so-called Atbash encryption. Similar to the Caesar cipher, this was a character exchange algorithm. Here, the alphabet was applied backwards: An A became a Z, a B became a Y, a C became an X until finally a Z became an A. Transferring this system to the Hebrew alphabet resulted in Atbasch.

According to these two rather simple encryption methods, the Greeks used a wooden stick (scytale) around 400 B.C. to keep a message safe. The message was written on a parchment ribbon or a strip of leather that was wrapped around a wooden stick. The recipient needed a wooden stick with exactly the same diameter as the sender to decrypt the message.

Today's encryption methods

In the meantime, digital communication has become more and more important and has also gained in use. Sensitive data must be protected from malicious hackers and sometimes even from the internet service provider. A well-known software that is designed to protect against exactly that is PGP (Pretty Good Privacy). The program was published in 1991 by Phil Zimmermann.

In the so-called public key procedure, a key pair is used, which consists of a public and a private, secret key. The former can be used by anyone who wants to encrypt data, the private key is only owned by the recipient. More precisely, this means that the public key encrypts the message and the private key can decrypt it. This procedure is also called asymmetric procedure, but it is very computationally intensive, and the message cannot be sent to multiple recipients.

PGP therefore uses hybrid encryption. The message itself is symmetrically encrypted with a key generated randomly by the sender, the so-called session key. In addition, there is the public key of the recipient, which the sender must obtain. The session key is then encrypted with the public key. Thus the finished message contains the symmetrically encrypted document and an asymmetrically encrypted session key.

The recipient can now use his secret key to decrypt the session key again, which can decrypt the document symmetrically.

But you don't have to be an IT expert to send emails securely.

If I could now motivate you to send an encrypted email, you are probably asking yourself how. Did you know that you can send your messages securely with Frama RMail? They can be encrypted with a simple mouse click. You can learn more about the encryption methods used on our product page or in this blogpost.


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