# Vigenère cipher - sorted order

i'm new to cryptography so i feel sorry for this newbie question! Can anyone tell me how Vigenère work with sorted order? For example i have this in my book:

• 3124(SORTED ORDER)
• 312431243(REPEATED KEY)
• PLAINTEXT(PLAINTEXT)
• SMCMOUGBW(CIPHERTEXT)

Can you tell me how we get this number(3124) and ciphertext from this key(LADY)?

• Which book is that from? That approach is non standard. – CodesInChaos Jan 15 '17 at 14:51
• really? its from this GREEK book: ianos.gr/… It was written from a university teacher and he recommend this book for his security class. I'm from Greece – Polem Jan 15 '17 at 14:57
• Maybe the recommendation was for other sections of the book. But this kind of cipher is quite terrible. The actual keyword doesn't matter, and there are other words representing the same key. So for a 4 letter keyword, there are just $4! = 24$ possible combinations of the key. This is really, really bad. – tylo Jan 16 '17 at 10:46
• No,its from the section "Vigenere cipher" and says that this is another way for this algorithm. This example is actually the same with the example of the book. The book doesnt have any further information, only this example. If you know greek i can send you a picture or something. You guys make me feel so weird about the two teachers that wrote this book. :/ sorry for my bad english. – Polem Jan 16 '17 at 11:45