Self Generated Encryption Key Good Bad

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Self Generated Encryption Key Good Bad 3,7/5 3330 votes

Discover: Try the Vigenère Cipher Widget !


Suppose the encryption function F defines a group under functional composition. Then, applying the function twice (even using two different keys) results in output that can be decrypted in the same time as if the function had been applied once. The difference is that the decryption key is a third key, not used during the encryption. Process of changing information using an algorithm into another form unreadable by others unless they possess the key. Class of cipher that uses identical or closely related keys for encryption and decryption. Stream cipher. Summary of a file or message. In the case of self-generated keys, you must keep the encryptor with the storage module or the data will be unreadable. For applications where this is not practical, mediation is being developed to support the use of Pre-Placed Keys (PPK). With PPK support, the encryptor can be left in place so that only the storage module need be transported.

Self generated encryption key good bad for you

I've been tasked with building up some security exercises (basic CTF training kind of stuff) for work. This should contain a bit of crypto, but my knowledge in this space has been limited to using.

Omsi 2 steam key generator. Goals:

  • Understand how the Vigenere Cipher Algorithm works

  • Understand why simple frequency analysis doesn’t work against this cipher

  • Figure out what makes for a good v. bad secret key


Instructions:

  • You should have a partner for this exploration.

  • Go to the interactive Vigenère Cipher Widget

  • Click on buttons and try things out! Solve the mystery of what this tool is doing and how it’s doing it!


You should try each of the following - check off the DONE column once you’ve tried it


Try This

Details

Done

Encrypt a few different messages using different secret keys


  • Enter a text message in the box and secret key

  • Step through the encoding of each character to see what’s happening

  • Try a different secret key

X

Decrypt a message

  • Copy/paste the ciphertext of an encrypted message into the text message area.

  • Hit the button to “decrypt”

  • Now step through and see what happens

X

Find a “bad” secret key


  • Hint: try “A” or “AAAAA” or “GGGG” or any single character, what about other patterns?

  • What makes a key bad?

X

Find a “good” secret key


  • Use what you learned about bad keys and do the opposite

  • What are the characteristics of a good key?

X

Try to decrypt without knowing the key (in other words: try to crack it!)


  • Have one partner look away, while the other copy/pastes the ciphertext of an encrypted message into the text area, and deletes the secret key from view

  • Have the partner who looked away come back and try to crack the message

X

Bad

.

Thought Questions:

Generate bitcoin address key pair. You might want to play with the widget a little bit more in trying to answer these questions, but they can be answered based only on the properties of the Vigenère cipher.


  • Describe in your own words what the Vigenere Cipher Algorithm is doing.

The x-axis represents the letter being encrypted and the y-axis represents the associated letter of the key. The ciphers moves to the intersection between two. On each axis, the letter below keeps moving alphabetically downwards.

  • What makes for a good v. bad secret key using the Vigenere cipher? Give examples of a good key and a bad one and explain why.

A good key is one that is longer than the information being put in, not repetitive, and not a word unto itself. A bad key would be like 'AAAAA' or 'MYKEY' because those are predictable. A good key, like a good password, would be 'AWEVDEPOSA'.

  • Compare and Contrast the difference between a substitution cipher (Caesar or Random) and Vigenere, using the message “I think I can I think I can I think I can” to explain why Vigenère is a stronger form of encryption than a substitution cipher.

Vignere: UXSZMPADAZMEKLFZKLKDOSHJGYZXHRXJZRCZSD_MK
Random: RbhrmlRaemRbhrmlRaemRbhrmlRaem
With a repetitive message like 'I think I can', etc. it would be really easy for a hacker to predict the shift or substitution.

Types Of Encryption Keys


  • Will frequency analysis work to crack the Vigenere cipher? Why or why not? Keep your answer as simple as possible.

No, frequency analysis will not work because each letter does not represent the same letter every time.

Encryption Key Generator


  • If I promised you that the message at right was encrypted with the Vigenère cipher widget, would that make it easy to crack (yes or no)? Explain why. Your explanation should include a description of what you would need to know to decrypt this and how you might go about figuring that out.

Knowing this was a vignere cipher encrypted message would make this very difficult to crack. We would at least need to know the key to decrypt this,

Self Generated Encryption Key Good Bad For You



  • What if I told you that the message above was encrypted with the Vigenère cipher widget and the key I used was 10 characters long. Does that make it any easier to crack the message? Again, what would you need to figure out and how would you go about finding it?

That makes it easier because you could possibly figure out the association between the axes and look at repeated letters every ten, but it would still be extremely difficult.

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