Cryptographic Techniques and Algorithms NDE Practice Questions (Page 1)

Questions 1–5

1. 1expert · hard

   A company needs to encrypt data at rest in a database. They have a requirement that if a single encryption key is compromised, only a small portion of the data should be exposed. They also want to minimize the performance impact of encryption. Which strategy should they implement?

   • AUse RSA to encrypt each row individually with the database server's public key.
   • BUse envelope encryption: encrypt each data item with a unique data encryption key (DEK), and encrypt the DEKs with a master key.
   • CUse a single AES key for the entire database and store the key in the application code.
   • DUse a different symmetric key for each row, but store all keys in a plaintext table.
   Reveal Solution Discussion Select an answer first
2. 2application · medium

   Two branch offices need to establish a shared symmetric key over the internet to encrypt their VPN traffic. They want to ensure that an eavesdropper cannot learn the key, and they also want to confirm each other's identity. Which protocol or method should they use?

   • AUse a hash of the current date and time as the shared key and exchange it over a public chat.
   • BUse Diffie-Hellman key exchange combined with digital signatures for authentication.
   • CSend the symmetric key via email encrypted with the other office's public key.
   • DUse a brute-force attack to guess the other office's private key and derive the shared key.
   Reveal Solution Discussion Select an answer first
4. 3foundation · easy

   Which attack involves an attacker intercepting and possibly altering communications between two parties without their knowledge?

   • ASide-channel attack
   • BDictionary attack
   • CMan-in-the-middle attack
   • DBrute force attack
   Reveal Solution Discussion Select an answer first
5. 4application · medium

   A company wants to enable secure email between its employees and external clients. They plan to use S/MIME. What must the company set up to ensure that recipients can trust the sender's public key?

   • AUse a symmetric key shared with all clients.
   • BPublish each employee's private key on the company website.
   • CObtain a digital certificate for each employee from a trusted certificate authority (CA).
   • DExchange public keys manually via a phone call.
   Reveal Solution Discussion Select an answer first
6. 5expert · hard

   A security auditor is reviewing a system that stores hashes of sensitive documents. The auditor finds that the system uses unsalted MD5 hashes. Which attack is the auditor most likely concerned about, and what is the best remediation?

   • ASide-channel attacks; remediate by adding random delays to the hashing process.
   • BBrute-force attacks; remediate by using a longer MD5 hash.
   • CMan-in-the-middle attacks; remediate by encrypting the hash database.
   • DRainbow-table attacks; remediate by switching to salted SHA-256 or a stronger hash.
   Reveal Solution Discussion Select an answer first