The main drawback to __________, a symmetric-key encryption algorithm, is that its keys are only 56 bits.a.)AESb.)PGPc.)3DESd.)DES

Break Down the Problem

1. Identify the encryption algorithms mentioned in the options.
2. Determine which algorithm is associated with a key length of 56 bits.

Relevant Concepts

1. AES (Advanced Encryption Standard): supports key sizes of 128, 192, or 256 bits.
2. PGP (Pretty Good Privacy): primarily used for securing emails and does not have a fixed key size like symmetric encryption algorithms.
3. 3DES (Triple Data Encryption Standard): uses three 56-bit keys, effectively resulting in a total key length of 168 bits.
4. DES (Data Encryption Standard): utilizes a key length of only 56 bits.

Analysis and Detail

Examining each option:

• Option a (AES): It supports larger key sizes, so it does not match the description.
• Option b (PGP): It is not a symmetric-key algorithm in all contexts and does not have a 56-bit key specification.
• Option c (3DES): Utilizes 56 bits per key but in triple processing, hence longer than 56 bits in practice.
• Option d (DES): This algorithm is well-known for its 56-bit key size, making it vulnerable to brute force attacks.

Verify and Summarize

After analyzing each of the algorithms against the criterion of having a 56-bit key length, it is confirmed that DES is the only option that meets the requirement.

Final Answer

The main drawback to DES, a symmetric-key encryption algorithm, is that its keys are only 56 bits.