On the Subject of the Hill CM
Sometimes, you need to scale a mountain rather than a hill.
All letter-number conversions are to be done with respect to the scheme A1Y25Z0. All rows and columns of the matrices are numbered from 1 going down or right respectively.
Concatenate the letters on all numbered screens in order, and convert them into numbers. These numbers, in reading order, are entries in an N×N matrix, where N is the number of letters on a given numbered screen. This matrix will be labeled M.
If the Submit Button is white, use matrix M to decrypt the word. Otherwise, you will need to calculate the inverse matrix, I, to decrypt the word.
Concatenate the encrypted word with the letters on screen A (if any), then split this string into substrings of the same length as the width of the matrix. These will be the vectors to be used with the matrix.
Perform matrix-vector multiplication on each vector using correct matrix, M or I. To do this:
- For each row of the matrix, multiply the Xth entry of the row with the Xth entry of the vector.
- Take the sum of these numbers, this result will be the Xth entry of the resulting vector.
- Take each entry, modulo 26, and convert it to a letter. You should now have a decrypted set of letters
The instructions to calculate matrix I are written on the next pages.