Cryptography Lab Work

Lab Assignment 1: Steganography

Steganography is the practice of hiding a message or image within another message or image. People use this practice because an encrypted message may attract attention whereas an encrypted message that appears to be ordinary text may not. In this exercise, you will encrypt a message, and then take the encrypted message and make it appear more like an ordinary message so that it will not stand out. Next, you will take the steps to reverse the processes that you originally completed.

Instructions

· Capture a screen shot as you complete each one of the lab steps and paste it in the designated spot below each step.

Example:

Step 1:

If there is a question in a step, your response should be included directly under the screen shot of that step.

· Submit the lab worksheet as an attachment in the online course shell.

Lab Steps:

1. Go to the JavaScrypt Encryption and Decryption page, located at http://www.fourmilab.ch/javascrypt/javascrypt.html

2. Create a key and enter it into the text box under the “Key” section. (The text option button under the textbox should be selected.) Next, click the “Generate” command button. Copy the contents of the “Key” textbox into a text editor file, such as Notepad, and save it.

3. Then, go to the “Plain Text” box immediately underneath the “Key” text box and enter text that you want to be encrypted. (The “Codegroup” option button under the textbox should be selected.) Click the “Encrypt” command button.

4. Look at the “Cipher Text” text box located below the “Encrypt” command button. Explain what is there.

Encrypted cypher text

5. Go back to the “Plain Text” text box and click the “Clear” command button. Next, go back to the “Cipher Text” text box and click the “Decrypt” command button.

6. Look back in the “Plain Text” text box. What do you see? Discuss what happened.

Dycripted Cypher text.

7. Click the “Clear” option button under the “Plain Text” text box. Next, go back to the “Key” text box and click the “Clear” command button. Then, go back to the “Cipher Text” text box and click the “Decrypt” option button. What happens? Why? What do you see in the “Plain Text” text box?

Without a key, it cannot perform the decryption.

8. Next, go to the “Key” text box and enter the generated key from Step 2. Then, go back to the “Cipher Text” box and click the “Decrypt” command button. What do you see in the “Plain Text” text box? What happened and why?

9. Copy the contents of the “Cipher Text” text box to another location. You will need it in a couple of steps.

10. Go to the “Stego! Text Steganography” page, located at http://www.fourmilab.ch/javascrypt/stego.html

11. Paste the cipher text into the “Cipher Text” text box.

12. Click the “Hide” command button under the “Cipher Text” text box. Now, look at the “Hidden Text” text box. What happened and why?

E can see the decoded message.

13. Go back to the “Cipher Text” text box and click the “Clear” command button.

14. Next, go back to the “Hidden Text” text box and click the “Seek” command button. Look in the “Cipher Text” text box. What happened and why? It decoded the message into JavaScrypt-compatible cipher text

15. Click the “Select” command button and copy the text in the “Cipher Text” text box. Go back to the JavaScrypt Encryption and Decryption page, located at http://www.fourmilab.ch/javascrypt/javascrypt.html and paste the text into the “Cipher Text” text box.

16. Go back to the “Plain Text” text box and make sure that it is clear. If it is not, click the “Clear” command button. You also need to make sure that your key is entered as you left it before you went to the “Stego! Text Steganography” page.

17. Then, hit the “Decrypt” command button found under the “Cipher Text” box. What is in the “Plain Text” text box now? Discuss what happened. The decrypted text is placed in the Plain Text box