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Network Security - Public Key Infrastructure

By IncludeHelp Last updated : July 28, 2024

What is Public Key Infrastructure?

Public Key Infrastructure (PKI) is a framework that ensures secure electronic transfer of information. The cryptographic keys, public and private, are used to authenticate users and devices, thereby protecting sensitive data from unauthorized access. In today's digital age, PKI plays a fundamental role in supporting secure communications, online transactions, and identity verification.

Why is PKI Important?

Public Key Infrastructure (PKI) is important as it ensures data confidentiality by encrypting information, provides data integrity by ensuring information is not altered during transmission, enables authentication by verifying the identities of communicating parties, and supports non-repudiation by preventing entities from denying actions they performed.

For example, when you access your online banking account, PKI ensures that your login information is encrypted and secure, verifies that you are communicating with the legitimate bank server, and ensures that the transaction details cannot be altered or denied later.

How Does PKI Work?

PKI works by using cryptography and encryption techniques, both symmetric and asymmetric, involving a public key. The main challenge in PKI is ensuring that the public key belongs to the correct person, hence avoiding Man-in-the-Middle (MITM) attacks. This is resolved by using digital certificates that assign identities to keys, which makes verification easy and accurate.

Digital certificates, also known as X.509 certificates, uniquely identify people and electronic systems in the digital world. These certificates are issued by a Certification Authority (CA), which stores the user's public key along with other information in the certificate. The certificate includes a digital signature, which allows verification of the public key using the CA's public key.

Certifying Authorities (CA) play an important role in PKI. They issue and verify certificates, ensuring the information in a certificate is accurate and digitally signing it to prevent alterations. CAs generate key pairs either independently or in collaboration with the client. They issue digital certificates to clients after verifying their identity and digitally sign them to ensure the information remains unchanged. CAs publish certificates, making them accessible to users via an electronic directory or other distribution methods.

Obtaining a PKI Certificate

The following are the steps for obtaining a PKI certificate:

1. Generate a Key Pair: Create a public and private key.
2. Certificate Signing Request (CSR): Generate a CSR containing the public key and identification details.
3. Submit to CA: Send the CSR to a CA.
4. CA Verifies: The CA verifies the information and issues a digital certificate.
5. Install Certificate: Install the digital certificate on the server or device.

Common Uses of PKI

1. Secure Web Browsing (HTTPS)

• HTTPS: Uses SSL/TLS certificates to encrypt data transmitted between a web browser and a server.
• Example: When you access your bank's website, HTTPS ensures your login details and transactions are encrypted.

2. Email Security

• S/MIME: Uses digital certificates to sign and encrypt emails, ensuring only the intended recipient can read them.
• Example: A company uses S/MIME to protect sensitive business communications from interception.

3. Code Signing

• Code Signing Certificates: Ensure the authenticity and integrity of software by signing it with a digital certificate.
• Example: Software developers sign their applications to verify that the code has not been tampered with.

4. Internet of Things (IoT)

• Device Authentication: PKI secures communication between IoT devices by authenticating them with digital certificates.
• Example: Smart home devices use PKI to securely communicate with each other and with the central hub.

Challenges Addressed by PKI

• Man-in-the-Middle Attacks (MITM): PKI prevents attackers from intercepting and altering communications.
• Certificate Management: PKI helps in the effective management and revocation of certificates.
• Scalability: PKI supports the growing number of devices and users in the digital ecosystem.