November 28th, 2011, 02:08 PM
There is 26-letter English alphabet. There is the plain text: HELLO
Encode the text with exponential cipher (Ek(x) = 7x3 mod(26)).
The cipher text is:
a. not possible to encode , it is against the rules
b. not possible because there is not enough information
December 25th, 2011, 11:26 AM
One of those is quite obviously the answer, without doing any working out. Look at the pattern of the plaintext, then look at the pattern of the ciphertext.