Practice Strings and Encoding with the exercise "Encryption/Decryption of Enigma Machine"

2648

Learning Opportunities

This puzzle can be solved using the following concepts. Practice using these concepts and improve your skills.

Statement

Goal

During World War II, the Germans were using an encryption code called Enigma – which was basically an encryption machine that encrypted messages for transmission. The Enigma code went many years unbroken. Here's How the basic machine works:

First Caesar shift is applied using an incrementing number:
If String is AAA and starting number is 4 then output will be EFG.

A + 4 = E
A + 4 + 1 = F
A + 4 + 1 + 1 = G

Now map EFG to first ROTOR such as:

ABCDEFGHIJKLMNOPQRSTUVWXYZ
BDFHJLCPRTXVZNYEIWGAKMUSQO

So EFG becomes JLC. Then it is passed through 2 more rotors to get the final value.

If the second ROTOR is AJDKSIRUXBLHWTMCQGZNPYFVOE, we apply the substitution step again thus:

ABCDEFGHIJKLMNOPQRSTUVWXYZ
AJDKSIRUXBLHWTMCQGZNPYFVOE

So JLC becomes BHD.

If the third ROTOR is EKMFLGDQVZNTOWYHXUSPAIBRCJ, then the final substitution is:

ABCDEFGHIJKLMNOPQRSTUVWXYZ
EKMFLGDQVZNTOWYHXUSPAIBRCJ

So BHD becomes KQF.

Final output is sent via Radio Transmitter.

Input

Line 1: ENCODE or DECODE
Line 2: Starting shift N
Lines 3-5:
BDFHJLCPRTXVZNYEIWGAKMUSQO ROTOR I
AJDKSIRUXBLHWTMCQGZNPYFVOE ROTOR II
EKMFLGDQVZNTOWYHXUSPAIBRCJ ROTOR III
Line 6: Message to Encode or Decode

Output

Encoded or Decoded String

Constraints

0 ≤ N < 26
Message consists only of uppercase letters (A-Z)
1 ≤ Message length < 50

Example

Input

ENCODE
4
BDFHJLCPRTXVZNYEIWGAKMUSQO
AJDKSIRUXBLHWTMCQGZNPYFVOE
EKMFLGDQVZNTOWYHXUSPAIBRCJ
AAA

Output

KQF

Solve it

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