In encryption, a key is used to:

In encryption, a key is used to:

• A. To encrypt and decrypt the data
• B. To compress the data
• C. To verify the data integrity
• D. To route the data

Answer: (A)

The key in encryption is what controls the transformation of data so that it can only be read by someone who has the right key. In symmetric encryption, the same key is used to both scramble (encrypt) the plaintext and to unscramble (decrypt) the ciphertext, enabling the intended recipient to recover the original data. In asymmetric (public-key) schemes, one key encrypts and another key decrypts, but the essential idea remains: the key is what makes the data readable again only by those with the correct key, preserving confidentiality. Other functions listed aren’t provided by the key itself. Compression is a separate data-reduction process, not part of the encryption key’s role. Data integrity is checked with hashes or Message Authentication Codes, which ensure the data hasn’t changed, but aren’t what decrypts the content. Routing is about directing data through the network, not about transforming data for confidentiality.

The key in encryption is what controls the transformation of data so that it can only be read by someone who has the right key. In symmetric encryption, the same key is used to both scramble (encrypt) the plaintext and to unscramble (decrypt) the ciphertext, enabling the intended recipient to recover the original data. In asymmetric (public-key) schemes, one key encrypts and another key decrypts, but the essential idea remains: the key is what makes the data readable again only by those with the correct key, preserving confidentiality.

Other functions listed aren’t provided by the key itself. Compression is a separate data-reduction process, not part of the encryption key’s role. Data integrity is checked with hashes or Message Authentication Codes, which ensure the data hasn’t changed, but aren’t what decrypts the content. Routing is about directing data through the network, not about transforming data for confidentiality.