1) In the following encryption system: A → [Monoalphabetic Encryption (Key: K1)] → B → [Row Transposition Encryption (Key: K2)] → C K1 = POIUYTREWQASDFGHJKLMNBVCXZ K2 = 3241 Suppose the input A = goodwork Find B and C. First, you will need to encrypt A to get B, then encrypt B to get C.

 

The Input is given as A = goodwork.

Step-by-step explanation

We also have the key K1.

so to get b. we know that the plaintext letters are A,B,C,D,,.....till Z.

If you write ABCD.....Z and below that write the Key POIU.....Z

you can get the encrypted letter for each of the letter in the input.

ABCDEFGHIJ.......Z write all the letters

POIUYTREW........Z write the complete key

For each input letter the encrypted letter will be the letter that is at the same position in the Key, G is 7the letter, 7th letter in Key is R.

By doing this :

letter we get for G is R, For O we get G, again O will be g, for d we get U, for w we get V, O is G, R is K, and K will be A

So B will be RGGUVGKA

Now row Transposition key is 3241 , number of columns is 4. we have 8 letters in B so there will be two rows.

3 2 4 1

R G G U

V G K A

We will write the letters below column 1 first which is UA ,then letters under column 2, GG, then letters under col 3 RV, then letters under column 4 GK.

Therefore, C will be : UAGGRVGK