Understanding Cryptographic Stream Ciphers: RC4, AES, DES, and Blowfish

Cryptographic Stream Cipher: What You Need to Know

Which of the following is a cryptographic stream cipher?

A. AES

B. DES

C. Blowfish

D. RC4

Final answer:

Among the given options, RC4 is the cryptographic stream cipher. AES, DES, and Blowfish are block ciphers, not stream ciphers.

Explanation:

The correct answer to the question, 'Which of the following is a cryptographic stream cipher?' is D. RC4. A stream cipher is a method of encryption where each bit of plaintext is combined with a pseudorandom cipher digit stream. RC4 (Rivest Cipher 4) is a widely used software stream cipher.

On the other hand, AES (Advanced Encryption Standard), DES (Data Encryption Standard), and Blowfish are block ciphers, which means they encrypt data in blocks, rather than one bit at a time.

Question:

Why is RC4 considered a cryptographic stream cipher, while AES, DES, and Blowfish are not?

Answer:

RC4 is considered a cryptographic stream cipher because it encrypts data by processing it one bit at a time, using a pseudorandom cipher digit stream. On the other hand, AES, DES, and Blowfish are block ciphers, which encrypt data in fixed-size blocks rather than individual bits.