PicoCTF 2018 Walkthrough – Caesar Cipher 1

Caesar Cipher 1

Caesar Cipher 1

Category: Cryptography

Points: 150


This is one of the older ciphers in the books, can you decrypt the message? You can find the ciphertext in /problems/caesar-cipher-1_2_73ab1c3e92ea50396ad143ca48039b86 on the shell server.



If you are interested in cryptography or if you have read any basic article related to cryptography you have probably come across Caesar Cipher as it is one the basic and ancient ciphers in cryptography.

Caesar cipher is a very intuitive cipher to understand and implement. You just take a  letter and shift it be a fixed number which is called a key and you will get an encrypted message. For more information on the same, you can visit Wikipedia here.

Now coming to the problem in hand we have to decrypt the message in the file attached with the problem. On downloading and inspecting the file we get the following contents inside:


We are not sure of the key which is important in solving the problem but we can always use google for this. I found a website where we can insert any ciphertext and it will tell the probable plaintext with the shifts that it applied. You can look it up here

On entering our ciphertext we found out that with the shift of 6 we get a somewhat readable answer and then I entered the same in the text box in the website and voila easy 150 points.

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