Can you recover an AES encryption key if you know the unencrypted content? [duplicate]

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Is it possible to find key开发者_StackOverflow to decrypt ciphertext by having the original plain text ?

Suppose I have encrypted a string with AES256 and someone else knows the unencrypted content of that string. Given the encrypted string, would it be any easier for that person to recover the encryption key given that they know the original unencrypted string?

Thanks..

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No, it shouldn't. If this was possible then AES would be susceptible to a know-plain text attack making it non secure.`