Plaintext to Hexadecimal In AES, while Converting Plain text to HEX in this image, how is X 23 and not 17 while all others are in Hex state.

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    $\begingroup$ This is one of the example questions that deserves downvotes. What is the source of these images? How reliable are they? Why do you think some of them is not hexadecimal? Hex contains $0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F$. What you see there is the byte where a byte is two hexes. $\endgroup$
    – kelalaka
    Jan 9 at 14:16
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    $\begingroup$ X is 23 and not 17 because the author made a (minor) error: they forgot to convert 23 from decimal to hexadecimal for that particular byte (as an aside they use an unusual representation of characters, rather than ASCII or it's superset UTF-8 most used by AES applications; an unusual padding; and ECB mode, which is not secure in a chosen plaintext attack model even for short messages). I'd question that source (never trust a random one), and any advice to use it. Update: I likely found the source (a ≈750 page book); it's too verbose for my taste, and has some quite serious errors. $\endgroup$
    – fgrieu
    Jan 9 at 15:59
  • $\begingroup$ Yep, looks like a bug to me. Errors happen. Don't know if there is anything else to the question, but without source I guess not. $\endgroup$
    – Maarten Bodewes
    Jan 9 at 21:12


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