Question

Consider a plain text message i am a hacker. encrypt it with the help of the followingalgorithm:

(a) replace each alphabet with its equivalent 7-bit ascii code
(b) add a 0 bit as the leftmost bit to make each of the above bit patterns 8 positions long.
(c) swap the first four bits with the last four bits for each alphabet.
(d) write the hexadecimal equivalent of every four bits.

Answer 1

The algorithm to encrypt the plain text message involves replacing each alphabet with its equivalent ASCII code, adding a 0 bit, swapping the first four bits with the last four bits, and writing the hexadecimal equivalent of every four bits.

Step-by-step explanation:

The correct answer is option C. According to the given algorithm, here are the steps to encrypt the plain text message 'i am a hacker':

1. Replace each alphabet with its equivalent 7-bit ASCII code: 'i am a hacker' becomes '105 32 97 109 32 97 32 104 97 99 107 101 114'.
2. Add a 0 bit as the leftmost bit to make each of the above bit patterns 8 positions long: '105 32 97 109 32 97 32 104 97 99 107 101 114' becomes '01001001 00100000 01100001 01101101 00100000 01100001 00100000 01101000 01100001 01100011 01101011 01100101 01110010'.
3. Swap the first four bits with the last four bits for each alphabet: '01001001 00100000 01100001 01101101 00100000 01100001 00100000 01101000 01100001 01100011 01101011 01100101 01110010' becomes '10010100 00000100 10001000 10011101 00000100 10001000 10000100 10001000 10001000 10000100 10000100 10000100 10001001'.
4. Write the hexadecimal equivalent of every four bits: '10010100 00000100 10001000 10011101 00000100 10001000 10000100 10001000 10001000 10000100 10000100 10000100 10001001' becomes '94 04 88 9D 04 88 84 88 88 84 84 84 89'.

Therefore, the encrypted message is '94 04 88 9D 04 88 84 88 88 84 84 84 89'.