title: can I decrypt an encrypted data if I have input and output and the method but dont have the key?
body: <p>This is a security question, What if I give to the user:</p>
  
  <ul>
  <li>a sample input before encrypting </li>
  <li>a sample output after encrypting </li>
  <li>the encryption method </li>
  </ul>
  
  <p>but I did not provide the correct key for the encryption method, would it be easily that the user can find the encryption key?</p>
  
  <p>Thanks in advance. </p>