The Date Shift cipher is a much harder code to break than, for example, the more simple Shift cipher. This is because the shift number varies from letter to letter, and also because it’s polyalphabetic (this means that a single number can represent multiple letters). I’ll explain it all in the video.


[am4show have=’p8;p9;p11;p38;p102;p154;’ guest_error=’Guest error message’ user_error=’User error message’ ]



 

Download Student Worksheet & Exercises


What do you think about the Date Shift cipher? The possibilities for numerical keys are endless. You can use the date you’re sending the message, birth dates, phone numbers, and more! Just remember to start decoding by writing the key numbers over the top of the encoded cipher. And always makes sure the decoder has the correct numerical key!


Exercises


  1. Which kind of key is used in date-shift ciphers?
  2. In which direction is the cipher shifted when decoding?
  3. How do you describe a cipher where a specific alphabetical letter represents more than one letter?

What would be the date shift key codes for the following?


  1. April 4th  1998 (Don’t forget that the key needs six digits! Use “04” for the date.)
  2. Jan. 28th 2012
  3. Nov. 30th 2011

Encode the following:


  1. COME TO MY HOME : March 16th 1999
  2. THEY HAVE JUST LEFT : June 1st 2001

What are the original messages? (These messages were sent on July 16th 1992)


  1. GUBZC GOGNZ
  2. MKFZV GAZTO GROZQ

[/am4show]


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Comments

4 Responses to “Date Shift Cipher”

  1. Whoa – you are so right! The answers I get are these:
    9. GLBZC GNHNQ
    10. MLFZT GAATO GRMZQ

    Does it match what you get also? So sorry about that – I will get the new ones published right away!

    Aurora

  2. We enjoyed the video on the Date Shift Cipher and printed out the worksheet to work some more problems. We are having difficulty with numbers 9 and 10 however. The cipher does not seem to work. This is what we get and it does not match your answer key. Any suggestions?

    #9 – GNATTEOZT
    #10 – MDETMEASSIXPOSP

  3. Hey thanks! I appreciate the correction so we can make it better. 🙂

  4. Laura Stephenson says:

    Hi, Aurora. I just wanted to comment that you actually made an error in the video. When you deciphered the “N” in “Under” you shifted it over 6 and came out with “S”. When I counted it was “T”, not “S”, but of course, I may be wrong. Just wanted to let you know! 🙂