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I'm looking for a method of encryption that fulfills the following parameters: To still be able to display a result even if decrypted with the wrong key. If the encrypted and decrypted message is found, the key cannot be worked out. Forgive me if I'm being stupid but I'm new to this area! Thanks

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  • $\begingroup$ What is the nature of the ciphertext for which its plaintext is known? If an encryption scheme is secure against known-plaintext-attacks then it will not "be broken" even if an attacker has access to the decryption of several ciphertexts. On the other hand, if the ciphertexts for which the underlying plaintext is known is of the attacker's choice, then you would need a CPA-secure scheme. $\endgroup$ – Daniel Mar 30 '17 at 14:32
  • $\begingroup$ You probably need to elaborate a bit on what you mean with "still be able to display a result". For typical ciphers, you would get bogus output if you use the wrong key. Are you looking for a scheme that allows you to decrypt one ciphertext to two (or more) meaningful plaintexts depending on which key you use? $\endgroup$ – Joost Mar 30 '17 at 15:29
  • $\begingroup$ @Joost Sorry, I mean exactly that, a bogus output. This is so that the attacker wouldn't know if they got the right output or not if the message was randomly generated. Would the bogus output be the same length as the plaintext real output? $\endgroup$ – OllieHooper Mar 30 '17 at 17:03
  • $\begingroup$ @Daniel Thank for explaining it, an encryption scheme secure against known-plaintext-attacks would be what I need. Thank you for your help! $\endgroup$ – OllieHooper Mar 30 '17 at 17:05
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    $\begingroup$ You should look at honey encryption. $\endgroup$ – Occams_Trimmer Mar 30 '17 at 17:30
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The point of "modern" cryptography is that "the strength" relies solely on the key. What you are describing is called a known-plaintext attack and state of the art algorithms (like AES) should not be prone to it.

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  • $\begingroup$ With AES encryption can the key be something that is easily remembered, such as a 10 character password? $\endgroup$ – OllieHooper Mar 30 '17 at 17:07

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