cryptography basics part iv

COMPOSITION OF CIPHERS

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In previous articles of cryptography we learnt how to encrypt a text using block substituted ciphers and transposition ciphers.these are good ciphers to a noob but these ciphers are cakewalk for a man having appreciable knowledge of cryptography.so let us make our ciphers even harder to crack using composition of ciphers.
so what really is composition of ciphers?? it is nothing but making a harder cipher using ciphers we already know.Double columnar cipher which we learnt in previous section is an example of this approach.
First let us apply this for block substituted ciphers.we learnt monosubstituted cipher and polysubstituted cipher.let us try to combine both the ciphers.
let us take the example "WELCOME TO FREE LEARN HACKING"

1. write the text in the blocks of length 5 "WELCO METOF REELE ARNHA CKING "
2. first applying key for polysubstituted cipher take key as replace first alphabet by its first successor,second alphabet by its second successor,third alphabet by its third successor,fourth alphabet by its fourth successor,fifth alphabet by its fifth successor
   our encrypted text will become "XGOGT NGWSK SGHPJ BTQLE DMLRL"
3. Now apply monosubstituted cipher ,deciding our key as replace each alphabet with their second successor like A from C
   now our text will become "YHPHU OHYTL JHIQK CURMF ENMSM"

This our new secret code and believe on me it is better than previous one.

Now let us experiment for route ciphers and columnar transposition cipher.we will be first performing route cipher and then columnar transposition

1. let us take the example "WELCOME TO FREE LEARN HACKING"
2. write the text in the blocks of length 5 "WELCO METOF REELE ARNHA CKING "
3. now we will apply route cipher therefore write in form according to the figure given below
   
4. now the encrypted text becomes WMRAC KINGA EFOCL EEERN HLOTE
5. now applying transposition cipher we get "WMRAC EEERN KINGA HLOTE EFOCL"
our new crypted text.

hey isnt it great forming powerful ciphers from existing ciphers we already know. we can also make composition of transposition cipher and substituted cipher, any permutation in your mind could result in a new cipher.