I remember having difficulty with this one as well.
If you have verified you have done what is asked in the book (left to right, top to bottom) and not getting an answer the website accepts, try another variation.
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On Q13 i believe im putting in the correct answer for the name of the needle since it seems pretty obvious what the answer is in the chapter but it keeps rejecting it, am i get the wrong idea with the question?
nvm i forgot you have to include ' in your answers
Is Q20 a Playfair Cipher or a cryptogram?
For figuring out the type of cipher, consider how each cipher works.
Simple substitution ciphers (cryptogram) would have a letter distribution where some letters are a lot more frequent than others.
Playfair and Vigenere would have "flat" letter frequency tables.
Also, from the way Playfair is composed you can look for things like:
does the code have an odd number of letters? (if so then it can't be Playfair)
if it has an even number of letters, break the code into pairs and check
does the code have double letter pairs (if so then it can't be Playfair)
and of course since Playfair has letters in a 5x5 table one letter is left out
such as Q but sometimes I/J are combined so it may or may not be Playfair
The author seems to be introducing ciphers in each chapter with increasing difficulty.
Hope that helps,
-Jack
Hi guys! I just got my book last week and I'm trying make my way through the questions. I am completely stuck on the sudoku questions for ch. 4. I have solved them correctly and have followed the instructions for the additions. Nothing works. I'm very stuck and frustrated. Could someone pm me with some help or let me know what I'm doing incorrectly? Thank you!