Cryptography Concepts EHE Practice Questions (Page 3)

Questions 11–15

1. 11expert · hard

   A multinational company needs to secure communication between its headquarters and a branch office. The branch office has limited computing power, and the company wants to minimize the computational overhead of key exchange while maintaining strong security. They also need to support digital signatures for document authenticity. Which approach best balances these requirements?

   • AUse AES-256 for key exchange and digital signatures.
   • BUse ECC for key exchange and digital signatures.
   • CUse SHA-256 for key exchange and digital signatures.
   • DUse RSA-4096 for key exchange and digital signatures.
   Reveal Solution Discussion Select an answer first
2. 12expert · hard

   A software vendor signs its releases with a digital signature. A security researcher discovers that the vendor's signing key has been compromised and is being used to sign malware. The vendor must respond quickly. Which action is the most critical first step to protect users?

   • AIncrease the hash algorithm strength from SHA-256 to SHA-512.
   • BRevoke the compromised certificate and issue a new signing key.
   • CAsk users to manually verify the signature using the vendor's public key.
   • DPublish a blog post warning users about the compromise.
   Reveal Solution Discussion Select an answer first
4. 13application · medium

   An organization issues digital certificates to employees for signing documents. An employee's private key is suspected to be compromised. What is the immediate action the organization should take to prevent further misuse?

   • ADelete the employee's account from the directory.
   • BRevoke the employee's certificate and add it to the certificate revocation list (CRL).
   • CReissue the same certificate with a new serial number.
   • DChange the employee's password and notify the employee.
   Reveal Solution Discussion Select an answer first
5. 14expert · hard

   A company is designing a system to securely store and transmit medical records. The system must ensure that records are confidential, that they cannot be altered without detection, and that the sender cannot deny having sent them. Which combination of cryptographic controls is required?

   • AEncryption for confidentiality and hashing for integrity only.
   • BEncryption for confidentiality, hashing for integrity, and digital signatures for non-repudiation.
   • CDigital signatures for confidentiality and encryption for non-repudiation.
   • DHashing for confidentiality and encryption for integrity.
   Reveal Solution Discussion Select an answer first
6. 15application · medium

   A security analyst notices that an attacker has been intercepting encrypted traffic between two servers and relaying it. The analyst suspects the attacker is capturing the encrypted data and re-sending it later to trick the receiving server. Which cryptographic control would most directly prevent this type of replay attack?

   • ARotate the encryption key every hour.
   • BEncrypt the traffic with a different symmetric algorithm, such as 3DES.
   • CInclude a timestamp and a unique nonce in each encrypted message.
   • DUse a longer encryption key, such as AES-256 instead of AES-128.
   Reveal Solution Discussion Select an answer first