Chapter 15 Key Management & KDC Quiz
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Questions and Answers

What is the primary advantage of symmetric-key cryptography over asymmetric-key cryptography for enciphering large messages?

  • It provides stronger security guarantees
  • It does not require the use of a Key-Distribution Center (KDC)
  • It requires a shared secret key between two parties (correct)
  • It is more efficient in terms of computational speed

    • Why is the distribution of keys considered a problem in symmetric-key cryptography?

  • It requires frequent updates to the keys
  • It is difficult to ensure secure and timely delivery of keys to all parties (correct)
  • It relies on a single point of failure for key management
  • It becomes more vulnerable as the number of parties increases

    • What is the role of a Key-Distribution Center (KDC) in symmetric-key distribution?

  • To authenticate members using public-key infrastructure (PKI)
  • To provide a central point for distributing and managing secret keys (correct)
  • To ensure secure and timely delivery of keys to all parties
  • To create a secret key for each member

    • Why is a secret key created by a KDC used only between the member and the KDC, not between two members?

    <p>To prevent the compromise of one secret key from affecting other members</p> Signup and view all the answers

    What distinguishes hierarchical multiple KDCs from flat multiple KDCs?

    <p>Flat KDCs have a single level of authority, while hierarchical KDCs have multiple levels</p> Signup and view all the answers

    What is the primary responsibility of a Public-Key Infrastructure (PKI) in key management?

    <p>To certify the authenticity of public keys</p> Signup and view all the answers

    In the context of network authentication, what is the main concern with the naïve solution of having every server know every user’s password?

    <p>Potential for compromise of all users if one server is compromised</p> Signup and view all the answers

    What are the main requirements for user authentication on the network, as discussed in the text?

    <p>Security, reliability, transparency, and scalability</p> Signup and view all the answers

    Why is the Trusted Third Party authentication server considered a single point of failure?

    <p>It has access to all passwords and can grant access to any server</p> Signup and view all the answers

    How does the use of a key derived from the password enhance the process of 'Single Logon' Authentication?

    <p>It eliminates the need for sending the password each time for authentication</p> Signup and view all the answers

    What is the main drawback of using plaintext passwords in the process of authentication?

    <p>Increased risk of impersonation attacks</p> Signup and view all the answers

    Why is the Trusted Third Party authentication server considered a convenient solution despite being a single point of failure?

    <p>It requires minimal application modification for user authentication</p> Signup and view all the answers

    How does the Kerberos protocol address the inefficiency associated with the naïve solution of having every server know every user’s password?

    <p>By allowing users to change their passwords without contacting every server</p> Signup and view all the answers

    What is the primary function of a Key-Distribution Center (KDC) in symmetric-key distribution?

    <p>To create a secret key for each member</p> Signup and view all the answers

    Why does symmetric-key cryptography require a shared secret key between two parties?

    <p>To ensure confidentiality and integrity of the communication</p> Signup and view all the answers

    What distinguishes hierarchical multiple Key-Distribution Centers (KDCs) from flat multiple KDCs?

    <p>The organizational structure in which they operate</p> Signup and view all the answers

    Why is a secret key created by a KDC used only between the member and the KDC, not between two members?

    <p>To ensure confidentiality in the key distribution process</p> Signup and view all the answers

    What is the main drawback of using plaintext passwords in the process of authentication?

    <p>The risk of password guessing attacks</p> Signup and view all the answers

    What is the primary advantage of symmetric-key cryptography over asymmetric-key cryptography for enciphering large messages?

    <p>Lower computational overhead</p> Signup and view all the answers

    In the context of network authentication, what does the Kerberos protocol use to prove a user's identity?

    <p>User's password</p> Signup and view all the answers

    What is the primary disadvantage of the naïve solution where every server knows every user’s password in network authentication?

    <p>Compromise of one server is enough to compromise all users</p> Signup and view all the answers

    Why is the Trusted Third Party authentication server considered a convenient solution despite being a single point of failure?

    <p>It simplifies user authentication procedures</p> Signup and view all the answers

    What is the main requirement for user authentication on the network, as discussed in the text?

    <p>Transparency in authentication</p> Signup and view all the answers

    What type of key does the Kerberos protocol use to access desired network services?

    <p>Session symmetric key</p> Signup and view all the answers

    What makes plaintext passwords an insecure choice in the process of authentication?

    <p>They can be intercepted during transmission</p> Signup and view all the answers

    Why is a secret key created by a Key Distribution Center (KDC) used only between the member and the KDC, not between two members?

    <p>To prevent compromise of multiple members if one member's key is compromised</p> Signup and view all the answers

    What is the primary advantage of using symmetric-key cryptography over asymmetric-key cryptography for enciphering large messages?

    <p>Faster encryption and decryption processes</p> Signup and view all the answers

    What distinguishes Kerberos Version 5 from its previous versions in network authentication?

    <p>Improved scalability for a large number of users and servers</p> Signup and view all the answers

    Why is using a key derived from the password beneficial for 'Single Logon' Authentication?

    <p>It avoids the need to re-enter the password for every service request</p> Signup and view all the answers

    Study Notes

    Symmetric-Key Cryptography vs Asymmetric-Key Cryptography

    • Symmetric-key cryptography is preferred for enciphering large messages due to its faster speed compared to asymmetric-key cryptography.

    Key Distribution in Symmetric-Key Cryptography

    • Key distribution is a major problem in symmetric-key cryptography, as the same secret key must be shared between two parties.
    • A Key-Distribution Center (KDC) helps in symmetric-key distribution by creating a secret key shared between the member and the KDC, not between two members.

    Role of Key-Distribution Center (KDC)

    • A KDC creates a secret key shared between the member and the KDC, not between two members.
    • The primary function of a KDC is to manage the distribution of secret keys in symmetric-key cryptography.

    Multiple KDCs

    • Hierarchical multiple KDCs have a tree-like structure, with each KDC serving as a backup for the one above it.
    • Flat multiple KDCs have a peer-to-peer structure, with no hierarchy.

    Public-Key Infrastructure (PKI) in Key Management

    • The primary responsibility of a PKI is to manage the distribution and authentication of public and private keys.

    Network Authentication

    • The main concern with the naïve solution of having every server know every user’s password is the security risk of storing many passwords.
    • The main requirements for user authentication on the network are identification, authentication, and authorization.
    • The Trusted Third Party authentication server is a convenient solution despite being a single point of failure.

    Kerberos Protocol

    • Kerberos protocol addresses the inefficiency associated with the naïve solution by using a centralized authentication server.
    • The protocol uses a ticket-based system to prove a user's identity and provide secure authentication.
    • Kerberos Version 5 distinguishes itself from previous versions with its improved performance and security features.

    Passwords in Authentication

    • The main drawback of using plaintext passwords is the risk of password exposure and unauthorized access.
    • Using a key derived from the password enhances the 'Single Logon' Authentication process by providing an additional layer of security.
    • Plaintext passwords are an insecure choice in the process of authentication due to the risk of password exposure.
    • A key derived from the password is used in the Kerberos protocol to access desired network services.

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    Test your understanding of key management, key-distribution center (KDC), session key creation, symmetric-key agreement protocols, Kerberos, authentication protocols, and certification authorities for public keys.

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