My assignment is to decode the message FVRMTGJTJJRMULSIRGBEMRNVFRC which was encoded
using the key matrix B. This is what I did. Can someone please tell me what I am doing wrong. Thank you.
B = {{4, 9, 15}, {15, 17, 6}, {24, 0, 17}}
R is the message put into numbers where A is 0, B is 1 and so on to Z being 25
R = {{5, 12, 9, 9, 20, 8, 1, 17, 5}, {21, 19, 19, 17, 11, 17, 4, 13,
17}, {17, 6, 9, 12, 18, 6, 12, 21, 2}}
b = Inverse[b]
{{-(289/5963), 153/5963, 3/89}, {111/5963, 292/5963, -(3/89)}, {408/
5963, -(216/5963), 1/89}}
J = Dot[b, R]
{{5185/5963, 645/5963, 2115/5963, 36/89, -(479/5963), 1495/5963, 2735/
5963, 1297/5963, 1558/5963}, {3270/5963, 5674/5963, 4738/5963, 53/
89, 1814/5963, 4646/5963, -(1133/5963), 1462/5963, 5117/
5963}, {-(1357/5963), 1194/5963, 171/5963, 12/89, 6990/
5963, -(6/5963), 348/5963, 5535/5963, -(1498/5963)}}
L = Mod[J, 26]
{{5185/5963, 645/5963, 2115/5963, 36/89, 154559/5963, 1495/5963, 2735/
5963, 1297/5963, 1558/5963}, {3270/5963, 5674/5963, 4738/5963, 53/
89, 1814/5963, 4646/5963, 153905/5963, 1462/5963, 5117/
5963}, {153681/5963, 1194/5963, 171/5963, 12/89, 6990/5963, 155032/
5963, 348/5963, 5535/5963, 153540/5963}}
