Although I had a security course in school a long time ago, I am effectively new to cryptography.

I have an encrypted text, the encryption key of 44 characters, the encryption method, (Fernet, which uses AES), the mode (CBC), the length of the key (128-bit), the padding (PKCS7) and the authentication (SHA256). The online decrypters I find do not provide the ability to enter all of these elements on one page. Is it possible to decrypt it online? Is there an order of steps that I have to use?

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    $\begingroup$ Welcome to Cryptography. This is off-topic here and if the 44 characters are random then the AES is secure here. Has AES-128 been fully broken?. What is the source of this question? $\endgroup$
    – kelalaka
    Sep 29, 2020 at 16:38
  • $\begingroup$ @kelalaka SE doesn't make it very clear what the rules of specific groups are. They have a big obnoxious banner when you first come to the page, which you have to click just to get it out of your way, and then the information is not on the page anywhere. As a candidate for a job, I was given a programming exercise. (There are no prohibitions against asking general questions related to it.) As a preliminary step to writing the code, I wanted to decrypt the text independently. $\endgroup$
    – Chozang
    Sep 29, 2020 at 17:00
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    $\begingroup$ Since the communities decide the rules over time. And they evolve, too. You did not get your informed badge!. Anyway. If you have only the ciphertext, you are going to perform ciphertext only attack. In this case you can check the padding is valid as in RSA's DES challange. The actual 128-bit key size is too big to search. There must be some special about the 44 chracters or here there is a padding oracle attack $\endgroup$
    – kelalaka
    Sep 29, 2020 at 17:12
  • $\begingroup$ So your assignment is to make a decrypter that decrypts the cypher text, but first you want to find what plaintext you are looking for with an online decrypter? I recommend settling on a decrypter that does part of what you need to do and write a script to do the rest. After you are done, have your script do more of it, and repeat until it does all of it. $\endgroup$
    – Nic
    Oct 2, 2020 at 2:21


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