Question 3

Explanation

The correct answer: Data compression is a method of reducing the size of a file or data to make it easier to store or transmit. This process doesn't involve encryption or the use of public key cryptography. Compression algorithms like LZ77, Huffman coding, or Run-Length Encoding are used for data compression. Public key cryptography, on the other hand, involves encryption and decryption of data using a pair of keys: public and private. The incorrect answers: Public key cryptography is used to create digital signatures. The private key is used to create a digital signature, and the public key is used to verify it. This ensures authenticity, integrity, and non-repudiation of the data. Public key cryptography is commonly used to encrypt emails. Protocols such as Pretty Good Privacy (PGP) and Secure/Multipurpose Internet Mail Extensions (S/MIME) use public key cryptography to secure email communication. Public key cryptography can also be used to encrypt files for secure storage or transmission. The recipient's public key is used to encrypt the file, and the recipient uses their private key to decrypt it.