Suppose we want to send the message āDO NOT PASSā, knowing that it has been enciphered
using the affine cipher. In the system we used, it has the 26 letters (A through Z) and 2 notations
(total number of letters and notations nQuestion 7
a) Suppose we want to send the message "DO NOT PASS", knowing that it has been enciphered
using the affine cipher. In the system we used, it has the 26 letters (A through Z) and 2 notations
(total number of letters and notations n=28 ), and will have the corresponding values found in
the following table.
If the deciphering function is
D(c)=3c+7mod28
write down the enciphering function for this cipher, and write down the ciphertext for the
message "DO NOT PASS". (Please present the function with the form ap+b where a and b
are non-negative integers less than 28.)
b) Show that GCD(414,662)=2, and express it as a linear combination of 414 and 662 using the
Euclidean algorithm. = 28), and will have the corresponding values found in
the following table.
Question 7
a) Suppose we want to send the message "DO NOT PASS", knowing that it has been enciphered using the affine cipher. In the system we used, it has the 26 letters (A through Z) and 2 notations (total number of letters and notations n = 28), and will have the corresponding values found in the following table.
A B c D E 0 1 2 3 4
F 5
G H 1 J 6 7 8 9
K L M N 10 11 12 13
0 P Q R S T U V W x Y z ! & 14 15 16 17 18 19 20 21 22 23 24 25 26 27
If the deciphering function is
D(c) = 3c + 7mod28,
write down the enciphering function for this cipher, and write down the ciphertext for the message "DO NOT PASS". (Please present the function with the form ap + b where a and b are non-negative integers less than 28.) b) Show that GCD(414, 662) = 2, and express it as a linear combination of 414 and 662 using the Euclidean algorithm.
