How can I figure out which kind of encrypting is used in plain-text message?
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Is it encoded or encrypted? Knowing the difference will help you narrow down the possibilities. – schroeder Nov 06 '16 at 12:30
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it is encrypted – Basel Alkhatib Nov 06 '16 at 13:38
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Since it's an assignement, I'd try the classic ciphers, like caesar, substitution and vigenere. – CodesInChaos Nov 06 '16 at 14:08
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Homework questions are frowned upon here. Tell us what efforts have you made so far and why did they not work out. – Limit Nov 06 '16 at 16:23
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I read the file and got all the information included within the file (the destination, ports and the messages) but there is a hidden message been sent after running the program for many times. I couldn't find the key message or how this message is encrypted. – Basel Alkhatib Nov 06 '16 at 16:28
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I searched a lot for how to encrypt and decrypt but I couldn't find any useful source other than sniffing for passwords or something like this – Basel Alkhatib Nov 06 '16 at 16:29
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In some points. But that one focuses on password encryption and I couldn't find it useful, that is why I post it my question here and not there. I am searching for more common way. – Basel Alkhatib Nov 06 '16 at 17:50
2 Answers
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Trial and error
The standard procedure is to make assumptions/guesses. You start with the simplest of the reasonably possible algorithms and perform an attack to which that algorithm is vulnerable. If it succeeds, you have solved the problem, and if you fail then you go on to the next likely algorithm.
For a university assignment you might initially assume a simple substitution cypher, attempt to break it based on e.g. letter frequencies, and if not, then it might be e.g. Vigenere cipher; etc.
Peteris
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So, if I have no background in encryption it will be difficult to know how this message got encrypted. – Basel Alkhatib Nov 06 '16 at 13:36
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1@BaselAlkhatib Properly encrypted text is supposed to appear no different from random text. You are not going to be able to tell what type is used unless you have some other contextual clues. – schroeder Nov 06 '16 at 16:56
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There are many toolkits about deciphering, like HackingBar (running Mozilla Browser) and Burpsuite (running with java environment). There is a picture about how to use Burpsuite.
And if you have plenty time, there is a classic book about this called "Cryptography Theory and Practice Third Edition" written by Douglas R. Stinson.
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5Encryption uses a key. Encoding just changes the representation. Sometimes we apply an encoding (hex or base64) to the ciphertext, so it turns into printable characters instead of random bytes. – CodesInChaos Nov 06 '16 at 14:08