Which of the following is a limitation of using symmetric encryption for securing communications?

Question

Which of the following is a limitation of using symmetric encryption for securing communications?

1. A. The encryption and decryption process is too slow
2. B. Key distribution and management become challenging (Correct answer)
3. C. It requires more computational resources than asymmetric encryption
4. D. It cannot be used for data at rest

Correct Answer

Option B — Key distribution and management become challenging

Detailed Solution & Explanation

The correct answer is Key distribution and management is difficult.

Key Points

• Symmetric encryption uses the same key to encrypt and decrypt, so both parties must already share that key secretly.
• Delivering the key safely to the other party — and managing keys as the number of participants grows — is its central weakness.
• The scale of the problem is mathematical: n users communicating pairwise need n(n−1)/2 distinct keys.
• The other options are wrong on fact: symmetric encryption is faster and needs less computation than asymmetric, and it is widely used for data at rest.

Additional Information

• Common symmetric algorithms: AES, DES, 3DES, Blowfish, RC4; asymmetric ones: RSA, ECC, Diffie-Hellman.
• Asymmetric encryption solves key distribution by using a public/private key pair — the public key can be shared openly — but is far slower.
• Practical systems combine both: asymmetric encryption negotiates a session key, which symmetric encryption then uses for the bulk data. TLS works exactly this way.
• Diffie-Hellman key exchange lets two parties derive a shared secret over an insecure channel without ever transmitting it.