85.2 Advanced Cryptography >> Public Key Infrastructure (PKI)

Introduction

Public Key Infrastructure (PKI) is a combination of hardware, software, policies, standards, and procedures that work together to provide a framework for secure communications and digital identity authentication using asymmetric cryptography.

Core Components of PKI

  1. Certificate Authority (CA):
    • A trusted third-party organization or company that issues digital certificates.
    • Ensures the digital certificate’s applicant is who they claim to be.
  2. Registration Authority (RA):
    • Verifies the identity of entities before the CA issues a digital certificate.
    • Can be considered a verifier for the CA before the digital certificate is issued.
  3. Digital Certificate:
    • A digital “passport” that establishes an individual’s or entity’s credentials when conducting transactions over the internet.
    • Contains the certificate holder’s name, serial number, expiration date, a copy of the certificate holder’s public key, and the digital signature of the CA.
  4. Certificate Revocation List (CRL):
    • A list of digital certificates that have been revoked by the CA before their expiration date.
    • A certificate can be revoked due to compromise or change in the status of the certificate’s owner.
  5. End Entities:
    • End users or devices (like servers) that employ the digital certificates.

How PKI Works

  1. Key Generation: A user or device generates a key pair, consisting of a public and a private key.
  2. Certificate Request: The user or device submits a request to the RA for a digital certificate.
  3. Authentication: The RA verifies the credentials of the user or device. Once authenticated, the request is forwarded to the CA.
  4. Certificate Issuance: The CA issues a digital certificate associated with the user’s or device’s public key.
  5. Certificate Distribution: Users or devices use the CA to establish trust. They can use digital certificates to authenticate one another and establish secure communication.
  6. Certificate Revocation: If necessary, a certificate can be revoked. The CRL is periodically updated to reflect this.
  7. Certificate Renewal or Expiry: Certificates have a set validity period. Post expiration, they must be renewed.

Benefits of PKI

  1. Authentication: Verifies the authenticity of a user’s or device’s identity.
  2. Confidentiality: Encrypts data to keep it confidential.
  3. Integrity: Ensures that data hasn’t been tampered with during transit.
  4. Non-repudiation: Ensures that a transaction, once authenticated, cannot be denied by the participant.

Challenges in PKI

  1. Complexity: Setting up a robust PKI environment requires a significant understanding of cryptographic principles and best practices.
  2. Cost: Implementing a secure PKI system, especially for larger organizations, can be expensive.
  3. Maintenance: Digital certificates need to be regularly renewed, and CRLs must be constantly updated.
  4. Interoperability: Ensuring different systems and applications recognize and trust the CA.

Conclusion

Public Key Infrastructure (PKI) provides a scalable way of encrypting and securing user data and transactions, as well as authenticating individual users. Though it comes with challenges, a well-implemented PKI is essential for maintaining trust in digital communications and transactions, especially in our current era of increasing cybersecurity threats.

Telecommunications and IT Handbook

Key terms in plain language

Open a term for a concise explanation of language used on this page.

Fiber Internet

Internet delivered through strands of glass using light. Fiber commonly supports high capacity, low latency, and strong upload performance, but availability must be confirmed for the exact address.

Cybersecurity

The practices and controls used to protect identities, devices, networks, applications, and data from unauthorized access, disruption, or manipulation.

Zero Trust

A security model that does not automatically trust a user or device because of its location. Access is continuously verified and limited to what is necessary.

SASE

Secure Access Service Edge combines networking and security capabilities in a cloud-delivered architecture so users and locations can receive consistent policy wherever they connect.

Identity and Access Management (IAM)

The systems and policies that determine who a user is, what resources they may access, and how that access is authenticated and reviewed.

Multi-Factor Authentication (MFA)

A login control requiring more than one form of verification, such as a password plus an authenticator app, security key, or biometric factor.