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How feasible is to brute force the ENCRYPTION key if you have

  • the clear-text message
  • the encrypted-version of the same message
  • you know that Rijandel is the encryption algorithm
  • you know that the salt is 2 bytes long
Leonardo
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1 Answers1

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The attack you describe is called a "known-plaintext attack". It was commonly used to break older encryption schemes, most notably Enigma in the second world war.

AES/Rijndael is not susceptible to known-plaintext attacks.

Further reading:

Wikipedia: Known-plaintext attack

Why is AES resistant to known-plaintext attacks?

AleksanderCH
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Nemec
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  • Hi! thank you for your answer, but i don't want to break the decryption key! i want to break the encryption! this might seem contradictory but i just need to send encrypted info... – Leonardo Jun 27 '19 at 01:30
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    @Leonardo Rijndael (including AES) is a [symmetric cipher](https://en.wikipedia.org/wiki/Symmetric-key_algorithm), the decryption and encryption key are (***must be***) exactly the same. Also, there's no such thing as a "salt" in symmetric cryptography; the closest thing is an "IV" ("Initialization Vector") or "nonce" (**n**umber used **once**) and it wouldn't be two bytes long. Salts are used in key-derivation functions (which take a password or other secret, and turn it into a key), though. – CBHacking Jun 27 '19 at 04:22