CISSP Security Architecture and Engineering Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  RSA

  Why it's wrong here

  RSA is an asymmetric cryptographic algorithm, meaning it uses a distinct public key for encryption and a private key for decryption, or vice versa for digital signatures. This public-key system eliminates the need for a shared secret key prior to communication, addressing key distribution challenges inherent in symmetric systems. Its security relies on the computational difficulty of factoring large prime numbers, making it suitable for key exchange and digital signatures rather than bulk data encryption.

• ✗

  RC4

  Why it's wrong here

  RC4 is a symmetric stream cipher, which encrypts data one byte or bit at a time, rather than in fixed-size blocks. It generates a pseudorandom keystream that is XORed with the plaintext to produce ciphertext, making it very fast for real-time applications. Unlike block ciphers, stream ciphers do not pad data to block boundaries, but RC4 has known vulnerabilities, especially when used improperly or with weak keys, leading to its deprecation in many protocols.

• ✓

  AES

  Why this is correct

  The Advanced Encryption Standard (AES) is a widely adopted symmetric block cipher, encrypting data in fixed-size blocks of 128 bits using the same secret key for both encryption and decryption. It supports key lengths of 128, 192, or 256 bits, offering robust security against brute-force attacks. As a highly efficient and secure algorithm, AES is the standard for protecting sensitive government and commercial data, making it the correct answer for a symmetric block cipher.

• ✗

  ECC

  Why it's wrong here

  Elliptic Curve Cryptography (ECC) is an asymmetric cryptographic algorithm that leverages the mathematics of elliptic curves over finite fields to create public and private key pairs. It provides comparable security to RSA with significantly smaller key sizes, leading to greater efficiency in terms of processing power, bandwidth, and storage. ECC is primarily used for digital signatures, secure key exchange, and encryption in resource-constrained environments like mobile devices and smart cards.

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