Question

What type of cipher relies on changing the location of characters within a message to achieve confidentiality?

A. Stream cipher
B. Transposition cipher
C. Block cipher
D. Substitution cipher

Answer 1

A Transposition cipher relies on changing the location of characters within a message to achieve confidentiality by rearranging the letters in the plaintext according to a predefined rule or pattern.

Step-by-step explanation:

A Transposition cipher relies on changing the location of characters within a message to achieve confidentiality. In this cipher, the letters in a plaintext are rearranged according to a predefined rule or pattern. One common technique is to divide the plaintext into blocks and make the same change to the order of the letters in each block.

For example, let's say we have the plaintext: 'HELLO WORLD' and we use a keyword 'KEY' to determine the size of the blocks and the change made to the order of the letters. The keyword 'KEY' has a length of 3, so we divide the plaintext into blocks of 3 letters: 'HEL', 'LOW', 'ORL', and 'D'.

Then, we rearrange the letters in each block according to the keyword 'KEY'. In this case, the keyword tells us to reorder the letters alphabetically, so the encrypted message would be: 'EHL', 'LOO', 'LOR', and 'D'. The final encrypted message is 'EHLLLOOLORD'.