Activity #1: Shift encoding Activity #2: MSC with word breaks Activity #3: Modular addition and subtraction Activity #4: Shift ciphers in Excel Activity #5: Cryptanalysis of shift ciphers Activity #6: Multiplication in modular arithmetic Activity #7: Dilation ciphers Activity #8: Affine functions and their inverses Activity #9: Decryption of affine ciphers Activity #10: Arithmetic on a cipher disk Activity #11: Affine alphabets Activity #12: Cryptanalysis of affine ciphers I Activity #13: Finding an affine key Activity #14: Vignère encryption and decryption Activity #15: Vignère cryptanalysis

Cryptograms

Cryptograms #1: MSC with word breaks. Cryptograms #2: General MSC. Cryptograms #3: Shift ciphers. Cryptograms #4: Affine ciphers. Cryptograms #5: Wordkey ciphers. Cryptograms #6: Vignère ciphers. Cryptograms #7: General MSC cryptograms with probable words.

Cryptanalysis Tools

Blank frequency histograms Standard frequency histogram From a count of 30,700 letters in The New York Times Frequency table From the same Times data List of frequent bigrams A Vignère square The multiplication table modulo 26 The addition table modulo 26 Blank cipher disks