CEH Practice Question: Advanced Topics: Wireless, Cloud, IoT, Cryptography

Answer analysis

Option-by-option breakdown

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

• ✗

  Uses a single shared key for both encryption and decryption

  Why it's wrong here

  This statement accurately describes symmetric-key cryptography, where the same secret key is used by both parties for encrypting plaintext and decrypting ciphertext. In contrast, asymmetric encryption, also known as public-key cryptography, fundamentally relies on a distinct pair of mathematically linked keys: one for encryption and the other for decryption. Therefore, using a single shared key is not a characteristic of asymmetric encryption.

• ✓

  Supports digital signatures

  Why this is correct

  Asymmetric encryption is foundational for digital signatures, providing non-repudiation, integrity, and authenticity. The sender uses their unique private key to encrypt a hash of the message, creating the digital signature. Recipients then use the sender's publicly available corresponding public key to decrypt the signature and verify the message's integrity and the sender's identity. This process ensures the message originated from the claimed sender and has not been tampered with.

• ✓

  Provides key exchange without prior shared secret

  Why this is correct

  Asymmetric encryption protocols, such as Diffie-Hellman, are specifically designed to enable two parties to securely establish a shared secret key over an insecure communication channel without any prior shared secret information. Each party generates a public/private key pair and exchanges public keys. Using their own private key and the other party's public key, they can independently compute an identical shared symmetric key, which can then be used for subsequent symmetric encryption of data.

• ✓

  Involves a public key and a private key

  Why this is correct

  Asymmetric encryption is defined by its use of a mathematically linked key pair: a public key and a private key. The public key can be freely distributed and is used for encryption or verifying digital signatures. Conversely, the private key must be kept secret by its owner and is used for decryption or creating digital signatures. These two keys are intrinsically related, yet it is computationally infeasible to derive the private key from the public key.

• ✗

  Typically faster than symmetric encryption

  Why it's wrong here

  This statement is incorrect; asymmetric encryption is significantly more computationally intensive and thus typically much slower than symmetric encryption algorithms. The mathematical operations involved in asymmetric cryptography, such as modular exponentiation with large numbers, require considerably more processing power and time. Consequently, asymmetric encryption is often used for secure key exchange or digital signatures, while symmetric encryption is preferred for bulk data encryption due to its superior speed.

Go deeper

Related to this question

Same concept, more angles

1 more way this is tested on CEH

These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.