Core Concepts of Accounting Information Systems 12th Edition by Carolyn Strand Norman, Mark Simkin

Exercise 12

Barra Concrete (XOR Encryption) Barra Concrete specializes in creating driveways and curbs for the residential market. Its accounting software uses exclusive OR (XOR) operations to convert the individual bits of a plaintext message into cyphertext. The rules are as follows:
In other words, exactly one of the bits must be a ''1'' and the other a ''0'' for the result of an XOR operation to be a ''1.'' To illustrate, suppose that the bits representing a single plaintext character were 1010 0101 and the secret key used just the four bits 1110. Here are the results of the XOR operation, using this key:

The encrypted bits are the cypher text, or 0100 1011, as shown. These (encrypted) bits are what the software would transmit to the final recipient.
Requirements
1. Decrypting the cipher text created by an XOR operation is easy-just use the same XOR operation on the encrypted bits! Demonstrate this for the example above.
2. Suppose the secret key were longer-the eight bits 1100 0011. Using this key and an XOR, what is the cipher text for the plaintext message ''Go, team'' if the bit configuration for these letters is as shown below. (Hint: the final answer consists of seven sets of data, each containing 8 bits.)