CSIS 4481: Cryptography and Data Security 7. You are using the ADFGX cipher to e
ID: 3749480 • Letter: C
Question
CSIS 4481: Cryptography and Data Security 7. You are using the ADFGX cipher to encrypt messages. Your encryption key consists of the following ADFGX matrix for Step 1 (the substitution step): and the following column headings for Step 2 (the transposition step) Encrypt the following message with the above cipher "Urgent. Enemy spotted." The ADFGX cipher is symmetric, as are all of the classical ciphers. That means the decryption key is the same as the encryption key. Use the same key from number 7 above to decrypt the following ciphertext: 8.Explanation / Answer
The given plaintext is "Urgent.Enemy spotted."
By using the matrix to encode , the text is obtained as , for U it is AA , then for R it is FX , like wise it is
obtained as , and filled in the the key or the column headings as :
The oder of permutation is (4,2,1,5,3)(3,2,5,1,4)-1
The column headings from 1 to 5 are written by order to obtain encoded text as :
XFGXGFGXAADADADXAGFADGFDFAFDDDAFFGAGXFAF
8. Like wise by using the same key 42153 the Encrypted text " AXFXD XFFXX DGFDG DFADD DGAAA F" is decoded to be :
The decoded code is :
LUYLMZTWSTIEV
4 2 1 5 3 A A F X F G A G F A F D A G F A A G X D D D X G D G A F F D F D A G A D X X X X