MAC
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MAC

Created by
@CourtlyErudition

Questions and Answers

Which type of attack involves modifying the content of a legitimate message?

  • Timing Modification
  • Impersonation
  • Content Modification (correct)
  • None of the above
  • Which type of authentication scheme is used for authentication between two communicating parties?

  • Public key authentication
  • Secret key authentication (correct)
  • None of the above
  • Both A and B
  • What is a MAC?

  • A piece of information that is computed from the message using a secret key and transmitted along with the message (correct)
  • A piece of information that is computed from the message using a symmetric key
  • None of the above
  • A piece of information that is computed from the message using a public key
  • Which type of MAC can be based on hash functions or symmetric cryptosystems?

    <p>Both A and B</p> Signup and view all the answers

    What is HMAC?

    <p>A MAC scheme based on a hash function and a shared secret key, applied twice with two keys derived from the original key</p> Signup and view all the answers

    In which mode is the message encrypted in MAC based on symmetric cryptosystems?

    <p>CFB mode</p> Signup and view all the answers

    What is authenticated encryption?

    <p>Providing both encryption and authentication</p> Signup and view all the answers

    Which authenticated encryption algorithm uses Galois/Counter Mode (GCM)?

    <p>GCM</p> Signup and view all the answers

    What is the purpose of including a timestamp in a message?

    <p>To authenticate the time of the message</p> Signup and view all the answers

    What is the purpose of a challenge/response authentication mechanism?

    <p>To prevent replay attacks</p> Signup and view all the answers

    What is the purpose of a Trusted Third Party in authentication?

    <p>To timestamp the message</p> Signup and view all the answers

    What is the CAESAR competition?

    <p>A competition organized by an international committee of cryptographers for authenticated encryption</p> Signup and view all the answers

    Which type of attack involves modifying the content of a legitimate message?

    <p>Content Modification</p> Signup and view all the answers

    Which type of authentication scheme is used for authentication between two communicating parties?

    <p>Secret key authentication</p> Signup and view all the answers

    What is a MAC?

    <p>A piece of information that is computed from the message using a secret key and transmitted along with the message</p> Signup and view all the answers

    Which type of MAC can be based on hash functions or symmetric cryptosystems?

    <p>Both A and B</p> Signup and view all the answers

    What is HMAC?

    <p>A MAC scheme based on a hash function and a shared secret key, applied twice with two keys derived from the original key</p> Signup and view all the answers

    In which mode is the message encrypted in MAC based on symmetric cryptosystems?

    <p>CFB mode</p> Signup and view all the answers

    What is authenticated encryption?

    <p>Providing both encryption and authentication</p> Signup and view all the answers

    Which authenticated encryption algorithm uses Galois/Counter Mode (GCM)?

    <p>GCM</p> Signup and view all the answers

    What is the purpose of including a timestamp in a message?

    <p>To authenticate the time of the message</p> Signup and view all the answers

    What is the purpose of a challenge/response authentication mechanism?

    <p>To prevent replay attacks</p> Signup and view all the answers

    What is the purpose of a Trusted Third Party in authentication?

    <p>To timestamp the message</p> Signup and view all the answers

    What is the CAESAR competition?

    <p>A competition organized by an international committee of cryptographers for authenticated encryption</p> Signup and view all the answers

    What is the purpose of a MAC in message authentication?

    <p>The MAC should ensure the integrity of the message and authenticate the sender as someone possessing the secret key.</p> Signup and view all the answers

    What is the difference between public key authentication and secret key authentication?

    <p>Public keys are used for authentication aimed at everybody (i.e., Digital signatures). A secret key shared by the two communicating parties is used for authentication between them (i.e., Message Authentication Code (MAC)).</p> Signup and view all the answers

    What are the three types of authentication attacks that can be prevented with MACs?

    <p>Impersonation, Content Modification, and Timing Modification.</p> Signup and view all the answers

    What are the two types of MAC schemes?

    <p>MACs can be based on hash functions or symmetric cryptosystems.</p> Signup and view all the answers

    What is HMAC?

    <p>HMAC (Hash-based Message Authentication Code) is a MAC scheme based on a hash function and a shared secret key, applied twice with two keys derived from the original key.</p> Signup and view all the answers

    What is the main idea behind MAC based on hash functions?

    <p>Concatenate the secret key and the message, and apply a hash function. The result is the MAC.</p> Signup and view all the answers

    What is the main idea behind MAC based on symmetric cryptosystems?

    <p>Encrypt the message using a symmetric cryptosystem in CBC (Cipher Block Chaining) or CFB (Cipher Feedback) mode using the shared secret key. The last block of ciphertext is used as a MAC.</p> Signup and view all the answers

    What are authenticated encryption algorithms?

    <p>Authenticated encryption algorithms provide both encryption and authentication.</p> Signup and view all the answers

    What is Galois/Counter Mode (GCM)?

    <p>Galois/Counter Mode (GCM) is an authenticated encryption algorithm where encryption is done in counter mode and a MAC of the ciphertext is computed using GHASH.</p> Signup and view all the answers

    What is the purpose of including a timestamp in a message?

    <p>To authenticate the time of the message.</p> Signup and view all the answers

    What is the purpose of a challenge/response authentication mechanism?

    <p>To prevent replay attacks.</p> Signup and view all the answers

    What is the purpose of a Trusted Third Party in authentication?

    <p>To timestamp the message.</p> Signup and view all the answers

    Which type of attack involves modifying the content of a legitimate message?

    <p>Content Modification</p> Signup and view all the answers

    What is the purpose of a Message Authentication Code (MAC)?

    <p>To authenticate the sender of a message</p> Signup and view all the answers

    What is the difference between authentication using public keys and authentication using a secret key shared between two parties?

    <p>Public keys are used for authentication, while secret keys are used for encryption</p> Signup and view all the answers

    What is the main idea behind a MAC based on hash functions?

    <p>Concatenate the secret key and the message, and apply a hash function</p> Signup and view all the answers

    What is HMAC?

    <p>A MAC scheme based on a hash function and a shared secret key</p> Signup and view all the answers

    What is the main idea behind a MAC based on symmetric cryptosystems?

    <p>Encrypt the message using a symmetric cryptosystem in CBC mode</p> Signup and view all the answers

    What is authenticated encryption?

    <p>Providing both encryption and authentication of a message</p> Signup and view all the answers

    What is the Galois/Counter Mode (GCM)?

    <p>An authenticated encryption algorithm</p> Signup and view all the answers

    What is the purpose of a timestamp in message authentication?

    <p>To authenticate the time of the message</p> Signup and view all the answers

    What is challenge/response in message authentication?

    <p>Each party sending a random number to the other when establishing a two-way connection</p> Signup and view all the answers

    What is the purpose of the CAESAR competition?

    <p>To organize a competition for authenticated encryption</p> Signup and view all the answers

    What is the purpose of a Trusted Third Party in message authentication?

    <p>To timestamp the message</p> Signup and view all the answers

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