A04-010-encrypting-exercises.md

"Passwords are like underwear: don’t let people see it, change it very often, and you shouldn’t share it with strangers."

Chris Pirillo, founder and CEO of LockerGnome, Inc.

Data Encryption

The internet is full of websites that offer encrypting files. The encrypted data is translated into another form or code and can only be read if the user knows the key. When talking about encrypted data, the term ciphertext is used, and plaintext-term when talking about unencrypted data.

In this lesson we will go through two simple exercises, that will teach you how you can encrypt your own files. These tricks may come in handy in daily life, especially when the users use the same computer and share the memory space with others.

File Encryption

Most operating systems on computers have the ability to encrypt the data, but for this exercise, we will be using a web browser-based encryption tool.

Here is the link for Freecrypt's site. url: videos/video.mp4 autoPlay: false poster: []

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Introduction to FreeCrypt

TrueCrypt offers a free, safe, and fast way to encrypt your data. You can encrypt any sort of files with the site.

For this exercise, we will be using a simple notepad file containing Dylan Thomas's poem Do not go gentle into that good night. You can use any file you have on your computer. Start

Step 1

Entering the site

When entering the site, both options for encrypting and decrypting are available.

Click the Encrypt a file-button first.

Step 2

Encrypting a file

Next search for the file you want to encrypt by clicking the Browse-button.

Step 3

Enter a pass phrase and encrypt the file

After you have uploaded the file, you will need to decide what kind of a passphrase. Later you will use it as a key to decrypt the file later. So remember to write it down if needed.

And lastly, click the Encrypt-button, this will start the process.

Step 4

The encryption is ready

The encryption is now done, and you can download the file by clicking the Save-button. This will download the file to your computer.

If you try and open the encrypted file, the pc may inform you that you will need an application to open it. There is no application for it, so the data is safe from outsiders if they get their hands on it.

Decrypting the Files

url: videos/video.mp4 autoPlay: false poster: []

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Step 1: Go back to the beginning The decryption can be done on the same site. This time choose the Decrypt a file-button.

Step 2: Find the encrypted file Browse your files to find the previously encrypted file.

Step 3: Do you remember the pass phrase? Hopefully, you remember the passphrase from when you encrypted the file. Enter the keyword and then you can decrypt the file.

Step 4: Decryption is done! The decryption is now done! You can again access the file by saving it to the computer.

"Encryption works. Properly implemented strong crypto systems are one of the few things that you can rely on."

Edward Snowden - Computer security consultant , famous whistleblower

Encrypting and Decrypting Text

For this exercise, we will use ciphers from Crypto Corner. The site has multiple types of different kinds of ciphers. The site was founded by a math teacher Dan Rodriguez-Clark, who developed an interest in codes and ciphers and decided to start Crypto Corner -site as a way to teach others about codes and ciphers.

At the moment, the has five different types of cipher categories, that each include more cipher-tools. Everyone also includes the introduction and will explain in detail how they work. Some have extra exercises to practice. They offer nice challenges for the brains.

Let's try out one of the ciphers. For this exercise, let's choose the Columnar Transposition Cipher. Clicking the link will open a new window and follow the steps presented below.

Introduction To Columnar Transposition Cipher

In this type of cipher, the plaintext is written out in rows and the ciphertext is then red in rows. The cipher also needs a key for encryption and decryption.

Let's go step by step. url: videos/video.mp4 autoPlay: false poster: []

'Encrypting and decrypting is not that hard when you have clear instructions on how to do it.'

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Step 1 Using the cipher is pretty simple, basically, you don't need anything else but the text to encrypt.

In this example, we are using a part of Dylan Thomas's poem Do not go gentle into that good night. You can use any text you want.

Step 2 Write your text on the Plaintext-slot and decide if you are going to use a randomly generated key or some other word of your choosing.

For this example, we are using the word "night", as it fits the poem's theme.

After this, press the Encrypt-button.

Step 3 The encrypted text will appear to the Ciphertext-slot.

If you want to see how the encrypted text was formed, you can press the Show grid -button. That will open the grid and will show how the first 10 lines formed.

Summary A pretty handy tool, right? The encryption uses the keyword to mix up the letters and is also required when decrypting the message. So remember to save the keyword for later use.

Decrypting the Text

The same tool can be used to decrypt the text of course. For this, you need the same keyword that you chose previously.

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  1. The key You need the key to decrypt the ciphertext. So make sure to remember it.
  2. The Decryption The text will be presented in one segment, but despite that it's readable.
  3. Cliphertext Paste the encrypted text here and press the Decrypt-button. The encrypted text will appear on slot above.

'As you may have noticed, encrypting data is fairly easy and quick. If you have an interest in codes and ciphers, you should take a look more closely at the Crypto Corner's content.'

Solve These Encryptions

Now you get to decrypt some data on your own. You will use the same sites as previously. After you are done with the decryptions, answer the questions so you can continue to the next lesson. Remember that you can scroll back up if you forgot something.

Task 1

Tässä Note-komponentti, jonka teksti alla This segment of letters is an encrypted poem. The Column Transposition Cipher was used for the encryption. You can decrypt it here with the keyword night.

LWUNGULAAOTRDIYTNNADTDHGDTNINRLHIITDGTTTNINAANSFTEOEGENAOEIHOHWECTAENHLTTYVOWNGETOGMOHSHIGDNAEETSOOLOGI

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Task 2

Let's take a look at how did the file encryption work with FreeCrypt's encryption tool.

Download the file below Go to FreeCrypt's site here Decrypt the file. The passphrase is oldyear

Download qnLtxvdQbzfawsAdrc.txt

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