I am a beginner and i need help in creating program for this

[alexwong89]

Hi, i am a beginner in c++ and i need help in typing out a program for this, anybody know how to do this??

Step 1: With the key written repeatedly over the intended plaintext, subtract the plaintext character with twice the value of the key individually.
Step 2: For each resultant character, interchange the position of 1st and 6th bit, 2nd and 5th bit, 3rd and 8th bit, 4th and 7th bit.


Test Data
---------
Plaintext: Singapore_Poly
Key: 2321
Initial Encrypted Text: Ocje]jkpaYLmhs
Final Encrypted Text: ø9Y©êYy )jÈéI;

[sohguanh]

Instead of coding straight away, try to work it out on paper or notepad. Let me give some kick-off point.

We do step 1

Plaintext: Singapore_Poly
Key: 2321

According to instruction, twice the value of key individually is 4642

So 'S' - 4 => 'O'
So 'i' - 6 => 'c'
and so on and so forth

So after step 1 you get Ocje]jkpaYLmhs

Now based on step 1 result, work on your step 2.

[alexwong89]

http://img31.imageshack.us/img31/8861/image1mcg.png

http://img233.imageshack.us/img233/6185/image2qs.png

http://img225.imageshack.us/img225/2233/image3bu.png