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Key Translation Center (KTC)

  • Facilitates secure communication between parties without direct key sharing.

  • Key Wrapping and Unwrapping: KTC unwraps keys from one entity and rewraps them for another using shared symmetric keys.

  • Secure Communication: Uses a long-term key shared with KTC for translation between parties.

  • Symmetric-Key Certificates: Encrypted under a symmetric master key managed by KTC for security.

  • Protocol: Involves encryption and decryption processes managed by KTC to maintain confidentiality.

Key Distribution Center (KDC)

  • A trusted server generating and distributing session keys for secure communication.

  • Components:

    • Authentication Service (AS): Verifies user identity and issues Ticket Granting Tickets (TGT).

    • Ticket Granting Service (TGS): Issues service tickets based on TGTs for access to resources.

  • Process:

    1. User logs in and requests TGT from AS.

    2. User presents TGT to TGS to access specific services.

Symmetric Key Distribution using Asymmetric Encryption

  • Public-key cryptosystems are mainly used to encrypt secret keys for distribution rather than direct data encryption.

Public-Key Distribution

  • Involves exchanging encrypted messages containing nonces and session keys between parties to establish secure communication.

Public Key Certificates

  • Digital document verifying public key ownership, with components including public key, owner identifier, and a signature from a trusted authority.

  • Typically issued by a Certificate Authority (CA) guaranteeing authenticity.

  • Participants can verify certificate validity and ensure it originates from a trusted CA.

X.509 Certificates

  • Standard format for public key certificates; widely used in internet protocols for securing communication.

  • Contains public key and is signed with CA's private key, ensuring trust.

  • Defines requirements for certificate creation, verification, and attributes such as version, serial number, and validity period.