1. Unit 8 Network Security

2. IP security (IPsec) protocol suite for secure Internet Protocol (IP)
works by authenticating and encrypting each IP packet of a communication session
includes protocols for establishing mutual authentication between agents
can be used in protecting data flows between a pair of hosts (host-to- host), between a pair of security gateways (network-to-network), or between a security gateway and a host (network-to-host).
IPsec is an end-to-end security scheme operating in the Internet Layer of the Internet Protocol Suite

3. Secure Socket Layer (SSL)
Standard security technology for establishing an encrypted link between a web server and a browser. 
 This link ensures that all data passed between the web server and browsers remain private and integral
SSL is an industry standard and is used by millions of websites in the protection of their online transactions with their customers.
SSL session starts with SSL handshake
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4. SSL Connection
To be able to create an SSL connection a web server requires an SSL Certificate.
Use public key cryptography
Perform SSL handshake
Successor of SSL is Transport Layer Security(TLS)
Practically use https in web browser

6. Pretty Good Privacy
Pretty Good Privacy or PGP is a popular program used to encrypt and decrypt over the Internet, as well as authenticate messages with digital signatures and encrypted stored files.

7. PGP : Working Mechanism