Cryptography Chapter 5: Key Management and Distribution
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Questions and Answers

What is the primary role of a Certificate Authority (CA) in a Public Key Infrastructure (PKI)?

  • To create malicious software for data interception
  • To issue and manage digital certificates (correct)
  • To store all user private keys securely
  • To develop encryption algorithms for public keys

    • Which class of certificate requires a thorough identity check before issuance?

  • Class 2
  • Class 4
  • Class 3 (correct)
  • Class 1

    • What is the purpose of certificate revocation by a CA?

  • To ensure all certificates remain in circulation
  • To prevent obsolete certificates from being used (correct)
  • To confirm the authority's operational capacity
  • To enhance encryption strength of existing certificates

    • What does the Registration Authority (RA) do in the certification process?

    <p>Confirms the identity of the certificate requester</p> Signup and view all the answers

    What happens to a certificate after a CA decides to revoke it?

    <p>A list of revoked certificates is maintained and made public</p> Signup and view all the answers

    What distinguishes Class 4 certificates from other classes?

    <p>They are specifically designed for high-trust organizations</p> Signup and view all the answers

    What is the purpose of making a CA's public key available?

    <p>To assist in verifying the CA's digital signatures on certificates</p> Signup and view all the answers

    Which component is responsible for the actual issuance of digital certificates in a PKI?

    <p>Certificate Authority</p> Signup and view all the answers

    How is public key infrastructure (PKI) primarily used to secure internet traffic?

    <p>By creating and managing public keys for encryption</p> Signup and view all the answers

    Which of the following is NOT a complementary component of PKI?

    <p>Public Key Assurance</p> Signup and view all the answers

    What is the purpose of the Publishing Directory in a PKI?

    <p>To publish user data and certificates</p> Signup and view all the answers

    What is the function of the CA in a PKI?

    <p>To issue and manage digital certificates for user verification</p> Signup and view all the answers

    What is the primary function of a public-key authority in a cryptographic system?

    <p>To maintain a directory of public keys</p> Signup and view all the answers

    How does Alice verify that the certificate from the authority is authentic?

    <p>By decrypting it with the authority's public key</p> Signup and view all the answers

    Why do certificate management systems generally avoid deleting certificates?

    <p>To retain the ability to prove their status for legal reasons</p> Signup and view all the answers

    What type of certificate does the root CA possess?

    <p>A self-signed certificate</p> Signup and view all the answers

    What is the purpose of using a timestamp in Alice's request to the public-key authority?

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

    Which of the following best describes a public key certificate?

    <p>A digital document that links a public key with an identity</p> Signup and view all the answers

    What is a common format used for storing private keys?

    <p>.p12 format</p> Signup and view all the answers

    What does the certificate chain illustrate in a CA hierarchy?

    <p>The path of certificates linking subordinate CAs to the root CA</p> Signup and view all the answers

    What role does X.509 play in digital certificates?

    <p>It is a standard for formatting digital certificates</p> Signup and view all the answers

    What is a primary purpose of key lifecycle management in cryptographic systems?

    <p>To ensure the secure generation, storage, and destruction of keys</p> Signup and view all the answers

    How does a Private Key Token enhance security for private keys?

    <p>It protects access to private keys through password security</p> Signup and view all the answers

    What is one key risk of having a single CA for public key certificates?

    <p>Potential widespread certificate failure if compromised</p> Signup and view all the answers

    What does a Private Key Token generally store?

    <p>The private key with a password restriction</p> Signup and view all the answers

    Which of the following is NOT true regarding the CA hierarchy?

    <p>The root CA can issue certificates to clients directly</p> Signup and view all the answers

    Which aspect of certificate management is primarily handled through the CA hierarchy?

    <p>Public key assurance and trust management</p> Signup and view all the answers

    What is the primary standard that digital certificates are based on?

    <p>X.509</p> Signup and view all the answers

    Which organization is responsible for digitally signing the information contained in a digital certificate?

    <p>Certification Authority (CA)</p> Signup and view all the answers

    What process do users follow to assure the authenticity of a public key in a digital certificate?

    <p>Signature Validation</p> Signup and view all the answers

    How does a Certification Authority (CA) ensure that the information in a digital certificate is not modified?

    <p>By signing the certificate digitally</p> Signup and view all the answers

    A Class 1 certificate can be obtained by merely providing a phone number.

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

    The Registration Authority (RA) is responsible for signing the certificates that it issues.

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

    Revocation of a certificate can occur if the private key is compromised.

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

    Class 4 certificates are generally intended for use by individuals.

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

    A Certificate Authority (CA) maintains a list of all revoked certificates in the environment.

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

    A Certification Authority (CA) is responsible for generating key pairs for clients without any identification checks.

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

    The digital signature included in a digital certificate is provided by the Certification Authority (CA).

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

    Class 3 certificates require extensive verification of the requestor's identity before issuance.

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

    Certificates allow users to exchange keys without consulting a public-key authority each time.

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

    Users can verify a digital certificate by using the public key of the client mentioned in the certificate.

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

    The primary function of a CA includes issuing digital certificates as well as publishing them.

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

    A digital certificate serves as an ID card for individuals only.

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

    Public-key authorities are responsible for maintaining a directory of public keys for all participants.

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

    The private key of a public-key authority is known to all participants.

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

    Bob's public key can be used by Alice to encrypt messages that are sent to Bob.

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

    Digital certificates can only prove identity for online transactions.

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

    Public key certificates are primarily used to encrypt messages in cryptographic systems.

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

    A timestamped message sent to the public-key authority assures the current validity of key requests.

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

    A Registration Authority (RA) is responsible for directly issuing digital certificates.

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

    The Certificate Authority (CA) does not need to verify the details of each user before issuing a digital certificate.

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

    Public Key Infrastructure (PKI) is solely responsible for transmitting data over the internet.

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

    The level of user verification in PKI is determined by the Certification Policy (CPS) implemented.

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

    A Certificate Management System (CMS) is used to permanently delete certificates once they are no longer needed.

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

    Intermediate components in a PKI include elements like the CA and the Publishing Directory.

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

    All web browsers contain inherent functionalities to support Public Key Infrastructure (PKI).

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

    The primary purpose of a Public Key Infrastructure (PKI) is to establish a secure way of transferring payment information only.

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

    In a PKI setup, the timestamp server is considered a complementary component.

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

    Digital certificates can be renewed or suspended, but cannot be revoked once issued.

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

    Certificate management systems typically delete certificates to ensure better security.

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

    A root CA's certificate is always a self-signed certificate.

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

    Private keys are generally stored on secure, removable storage tokens without password protection.

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

    A certificate chain illustrates a path of certificates from a root CA to any subordinate CA.

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

    The public key of a client is not included in the certificate.

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

    Root CAs do not require any verification before issuance of certificates.

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

    The CAs under subordinate CAs are signed by higher-level subordinate CAs in the hierarchy.

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

    Study Notes

    Cryptography (Classic & Modern) - Chapter 5: Key Management, Exchange, and Distribution

    • Key Management: Security of cryptographic systems relies heavily on secure key management. Cryptographic keys are special data and their lifecycle—generation, establishment, distribution, storage, archival, destruction, and usage—is critical. Weaknesses in handling cryptographic keys can compromise the benefits of strong cryptographic schemes. Poor key management is a frequent source of compromise.

    Key Distribution

    • Public Key Distribution: A cryptographic method using two separate keys: one private for decryption and one public for encryption, protecting data from unauthorized access. Anyone can obtain the public key without compromising security.

    • Key Distribution Method: The sender obtains the recipient's public key (email or key chain server), encrypts the message using it, and sends the resulting ciphertext. The recipient decrypts the message using their private key.

    • Public Announcement of Public Keys: A convenient method where participants broadcast their public keys to the community. However, this approach is vulnerable to malicious actors creating false public key announcements.

    • Public Key Servers: The distribution of public keys in public key cryptography, where a key pair is created. One key is kept private (private key) and the other (public key) is uploaded to a server for anyone to access. The public key can be used to send encrypted messages to the user.

    Digital Certificates

    • Digital Certificates: Considered digital identity cards for individuals, computers, or software. They verify the identity of the holder. X.509 is a standard format. Digital certificates include the owner's public key, issuing authority information, and the certificate's expiration date. A certification authority (CA) digitally signs the certificate to guarantee its integrity. Anyone can verify the authenticity of a certificate using the CA's public key.

    • Certificate Obtaining Procedure: A certifying authority (CA) verifies the identity of a client, issues a certificate containing the client's public key, and digitally signs the certificate. The CA ensures the information in the certificate is correct by checking the client's identity and digitally signing it.

    • CA Key Functions: Generating key pairs, issuing digital certificates (identifying and authenticating the user) and publishing certificates to a directory.

    • Verifying Certificates: CA's make their public key available, and anyone needing to verify a certificate can use the CA's public key to check the validity. This assures the certificate belongs to the claimed user.

    • Classes of Certificates: Different classes exist with varying requirements, including email address verification, additional personal information, and strict identity checks. Class-4 certificates are used by organizations needing high reliability.

    • Registration Authority (RA): A third-party assisting the CA by verifying the identity of individuals or organizations requesting certificates.

    • Public Key Certificates (PKC): PKC defines the requirements needed for a certificate to ensure its validity and prevent any form of counterfeiting. These are now considered the most secure key distribution/management systems.

    • Hierarchical Model of CAs: Multiple CAs can exist in a hierarchical structure where root CAs, intermediate CAs, and leaf CAs form a chain. This hierarchy builds trust relations making it possible for parties to not trust each other directly.

    Public Key Infrastructure (PKI)

    • Public Key Infrastructure (PKI): A set of roles, policies, hardware, and software used to manage digital certificates and public key encryption. It's crucial for secure communication over networks.

    Certificate Management System (CMS)

    • Certificate Management System (CMS): A system for managing certificates, enabling their publishing, temporary suspension, revocation, and renewal.

    • Private Key Tokens: Secret private keys can, but often aren't, stored on user computers. Private keys are frequently stored on secure, removable storage tokens with password protection.

    X.509

    • X.509 Certificates: A standard format for public key certificates and certification methods. Includes successive versions (v1, v2, v3) and extensions that have evolved over time to accommodate the needs of the environments they operate in.

    • X.509 Certificate Structure: The structure of X.509 certificates includes elements like serial number, signature algorithms, validity dates, public key information, issuer and subject identifiers, extensions, and digital signatures. Various extensions might exist pertaining to the certificate, depending on the type of data the certificate has.

    • X.509 Certificate Extensions: Allow modifications for additional information, supporting specific or unique situations. Extensions enable the addition of information beyond the basic entity identification for specific needs. Examples include key usage, holder/issuer information, or policies.

    • Trust Model in X.509 Certificates: The trust model in X.509 certificates defines hierarchical order and co-certification among certification authorities (CAs). This organization demonstrates how to reliably establish trust relations between entities, even when they may not both trust the same root CA.

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    Chapter 5 Key Management, Exchange and Distribution PDF

    Description

    This quiz covers Chapter 5 of Cryptography, focusing on the crucial aspects of key management, exchange, and distribution. Learn about the lifecycle of cryptographic keys and the methodologies for ensuring secure communication through public key distribution. Understanding these concepts is essential for maintaining security in cryptographic systems.

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