Another method of coding information is through the use of transportation ciphers.

Ex) Consider the message: NO HOMEWORK TONIGHT

Write the message in a 3*6 matrix and then use the transpose of the matrix as a key to encrypt the message. Use Q as a filler.
Ciphertext:NWNOOIHRGOKHMTTEOQ

You can encode a message by rearranging matrix columns according to alphabetical order of a key word.

Ex) Using crypto (146352) as a key, the matrix for NO HOMEWORK TONIGHT becomes
Ciphertext:NEOOMHWOKOTRNQHITG

Your recipient should know the key so that s/he can reorder the columns.

To use the TI-83, first convert teh elements of the matrix to their numerical equivalent. Consider the message: MATH IS DISCRETE

To store in matrix, press Matrix Edit [A] <enter>, r*c (in this cse 2*8), fill cells, then exit.

To transform the matrix use Matrix Math:

Transpose Matrix Try: [A]^T

Transpose Rows Try: row swap ([A])6T, 1, 4)

1. Try combining the previous examples to encode NO HOMEWORK TONIGHT numerically with columns switched and the matrix transposed. (Hint: Switching columns in [A] results in switching what in [A]^T ?)

2. Decode the message 1 17 11 14 14 0 0 13 13 19 19 18 19 20 8 6. Hint: What are the possible dimensions of a matrix used to encrypt this message?

3. Practice using matrices of different dimensions. Is there a difference in the difficulty of decryption?

4. Send messages to your friends using the techniques illustrated above.