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I've been studying encryption on a hobby basis, and wanted to know if I got this basic cypher construction right (this is another experiment, see the AES ECB experiment thread earlier).

Encryption:

  1. XOR plain text block, initialization vector and counter together.
  2. AES resulting block.
  3. Increment counter.
  4. Goto 1 until all plain text blocks are done.

Authentication tag:

  1. Sha256 cipher text.
  2. AES resulting hash using authentication key.
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  • $\begingroup$ As to the first part, this will answer your question: crypto.stackexchange.com/questions/14782/… $\endgroup$ – Richie Frame Mar 4 '15 at 20:21
  • $\begingroup$ For the second part, see crypto.stackexchange.com/questions/3229/… $\endgroup$ – Ilmari Karonen Mar 4 '15 at 21:03
  • $\begingroup$ Yeah, those posts explain it all. Thanks. It sure is easy to get this wrong. $\endgroup$ – Thorham Mar 5 '15 at 8:15
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    $\begingroup$ A common truth is: It is easy to design a scheme you can't break yourself. But it is an entirely different matter to design a scheme, which no one can break. $\endgroup$ – tylo Mar 5 '15 at 13:49

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