Public Key Infrastructure(PKI) in Network Security

 

Public Key Infrastructure(PKI)

Public Key Infrastructure (PKI) is a framework used to create, manage, distribute, verify, and revoke digital certificates and public keys.

PKI enables secure communication by providing:
  • Authentication
  • Data Integrity
  • Trust

It is commonly used over open networks such as the Internet.

Need for PKI
Public-key cryptography allows public keys to be shared openly. However, it does not by itself guarantee that a public key actually belongs to the claimed user.

PKI solves this problem by:
  • Verifying user identities.
  • Binding public keys with identities using digital certificates.
  • Establishing trust through trusted authorities.

Without PKI, systems may be vulnerable to Man-in-the-Middle (MITM) attacks.


Components of PKI

1. Certificate Authority (CA)
The Certificate Authority (CA) is a trusted entity in PKI that:

  • Issues digital certificates.
  • Digitally signs certificates.
  • Revokes certificates when they are compromised or expired.

CA acts as the root of trust in PKI.


2. Registration Authority (RA)
The Registration Authority (RA) assists the CA by:

  • Verifying the identity of users.
  • Approving or rejecting certificate requests.
  • Forwarding verified requests to the CA.

RA does not issue certificates.


3. Digital Certificate
A Digital Certificate, usually based on X.509, is used to:

  • Bind a public key with the identity of its owner.
  • Provide a certificate digitally signed by the CA.
  • Support authentication and secure communication. 

4. Certificate Repository

  • Stores issued certificates.
  • Allows users to retrieve and verify certificates

5. Certificate Revocation System
This system ensures that invalid or revoked certificates are not trusted.
Two commonly used mechanisms are:

CRL – Certificate Revocation List
A list containing certificates that have been revoked.

OCSP – Online Certificate Status Protocol
A protocol used to determine the revocation status of a digital certificate.


Working of PKI

User / Server
(Requests Certificate)
        ↓
Registration Authority (RA)
(Identity Verification)
        ↓
Certificate Authority (CA)
(Issues & Signs Certificate)
        ↓
Certificate Repository
        ↓
Client / Browser
(Verifies Certificate)

Steps
  1. The user or server requests a certificate.
  2. The RA verifies the identity.
  3. The verified request is forwarded to the CA.
  4. The CA issues and digitally signs the certificate.
  5. The certificate is stored in the certificate repository.
  6. A client or browser retrieves and verifies the certificate. 

Applications of PKI

  • HTTPS and SSL/TLS
  • Secure email systems
  • VPN authentication
  • Digital signatures
  • Software and code signing

Handwritten Notes- Download PDF

Video Explanation-Watch on YouTube

Comments

Post a Comment

Popular posts from this blog

B+ Tree in DBMS | B+ Tree in Data Structure

    B+  Tree A B+ Tree is a self-balancing multi-way search tree   All leaf nodes are present at the same level . Actual data records are stored only in the leaf nodes . Internal nodes contain only search keys . It is mainly used for efficient searching and sequential access . B+ Tree supports efficient range queries . Structure of B+ Tree Consider a B+ Tree node containing keys and children: Number of Keys Number of Children 1 2 2 3 3 4 In general, Number of children = Number of keys + 1 The leaf nodes are connected sequentially using links( Linked List ). Rules of B+ Tree For a B+ Tree of order m : At most: A node can have at most m children . A node can contain at most m − 1 keys. At least: An internal node must have at least [ m/2 ] children . An internal node must contain at least [ m/2 ] − 1 keys . Insertion...
Read more

Hashing in Data Structure | Collision Resolution Techniques | Hashing in DBMS

  Hashing in DBMS Hashing is a technique used to map data elements (keys) to specific locations in a hash table using a hash function. It allows insertion and retrieval of data efficiently     Hash Function A hash function converts a key into a hash code (index) , which is used to store and retrieve the data from a hash table.                                 h(k)=k mod m Where: k → Key m → Hash table size h(k) → Hash index  Hash Table A hash table is a data structure that stores data in an array format . Each position in the table is called a bucket , and the position is accessed using the hash function. Example Consider Keys                   (k) = 11, 18, 20, 25, 29, 33 Hash table size (m) = 7 Hash function:    h(k)=k mod m                     ...
Read more

Normalization in DBMS,(1NF,2NF,3NF,BCNF,4NF,5NF)

                      Normalization in DBMS Normalization divides a large table into smaller , logically related tables and connects them using appropriate keys. The main purpose of normalization is to reduce unnecessary duplication of data and prevent problems that may occur when data is inserted, updated, or deleted. 1. First Normal Form (1NF) A relation is said to be in First Normal Form (1NF) when every attribute contains a single, indivisible value . Conditions of   1 NF Each cell must contain only one value. Multiple values should not be stored in the same field. ·         Example Customer Items Purchased Gowsi Rice, Dal Tamil Soap ·   Here, the Items Purchased column contains more than one value for Gowsi . ·   Therefore, the table is not in 1 NF . Converting it into 1NF. ...
Read more