.NET Cryptography Namespaces and Class Hierarchy CASENET Practice Questions (Page 2)

Questions 6–10

1. 6expert · hard

   A developer is implementing a password verification system. The current code uses SHA256 to hash passwords. A security audit recommends using a key derivation function with a salt and iterations. Which change should be made?

   • AUse HMACSHA256 with a secret key
   • BContinue using SHA256 but add a static salt
   • CReplace SHA256 with Rfc2898DeriveBytes using a random salt and a high iteration count
   • DUse Aes to encrypt the password and store the ciphertext
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2. 7foundation · easy

   Which of the following is NOT a symmetric encryption algorithm class in .NET?

   • ADES
   • BRC2
   • CDSA
   • DTripleDES
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4. 8foundation · easy

   Which class is the abstract base for all asymmetric algorithms in .NET?

   • AHashAlgorithm
   • BAsymmetricAlgorithm
   • CSymmetricAlgorithm
   • DRandomNumberGenerator
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5. 9expert · hard

   A developer is implementing a hybrid encryption scheme where a symmetric key is encrypted with RSA. The symmetric key is derived from a password using Rfc2898DeriveBytes. The developer needs to ensure that the key derivation is performed correctly. Which code snippet correctly derives a 256-bit key for AES?

   • ASHA256.Create().ComputeHash(password)
   • Bnew Aes().CreateEncryptor().TransformFinalBlock(password, 0, password.Length)
   • CRandomNumberGenerator.Create().GetBytes(32)
   • Dnew Rfc2898DeriveBytes(password, salt, 10000).GetBytes(32)
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6. 10expert · hard

   A developer is implementing a password-based encryption system. They need to derive a 256-bit key from a passphrase and also generate a random salt. They want to use the most modern and secure approach. Which combination of classes should they use?

   • ASHA256 with a salt from System.Random
   • BRfc2898DeriveBytes with a salt from RandomNumberGenerator.Fill
   • CAes with a salt from RandomNumberGenerator.Create()
   • DRNGCryptoServiceProvider with a salt from Rfc2898DeriveBytes
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