... **Needham and Schroeder Authentication Protocol:** - N-S is a shared-key authentication protocol designed to generate and propagate a session key, i.e., a shared key for subsequent symmetrically encrypted communication. Note that there is no public key infrastructure in place. - Needham-Schroeder ...

... **2. S/MIME (Secure / Multipurpose Internet Mail Extension)** - It is enhancement of MIME protocol. -SI MIME adds some new content types to include security service to the MIME. All these new types include the parameter " application / pkcs7-mime", in which 'pkcs' defines "Public Key cryptography S ...

... **Secure Email :** 1. PGP : - (Pretty Good Privacy) - It provide email with privacy, integrity &authentication. - It can be used to create a secure e-mail message or to store a file securely for future retrieval. PGP provides following services : a. Message integrity b. Message compression. ...

... **Protocols of IPSEC :** - IPSEC defines two protocols - a. the Authentication Header (AH) - b. Encapsulation Security Payload (ESP) to provide authentication and for encryption for the packets at the IP level. **1.Authentication Header (AH)** (provide source authentication & data integ ...

... **IP SECURITY: ( IPSEC )** - IPSEC is a protocol to provide security for a packet at a Network layer which is often referred to as the Internet Protocol or IP layer. - IPSEC helps to create confidential & authenticated packets for the IP layer. - It can enhance the security of those client / ...

... **TLS: (Transport Layer Security )** - TLS protocol is the IETF standard version of SSL protocol. Whose goal is to come out with an internet version of - SSL & TLS are very similar with slight difference. Following are the differences between TLS & SSL 1. **Version :** the current versi ...

... **SSL ( Secure socket Layer )** This protocol is used for secure communication between the web browser & web server. SSL protocol is located between the application layer & transport layer of the TCP/IP protocol suite i.e the application layer does not forward the data directly to the tran ...

... **Kerberos** Many real-life systems use an authentication protocol called Kerberos the Needham - Shroeder is the basis of Kerberos. Version 4 of Kerberos is found in most practical implementation also version 5 is in use. **Working of Kerberos** There are four parties involved in Kerberos protoc ...

... **Knapsack Algorithm** • It is based on public key encryption algorithms and knapsack • Given a note of items, each with different weights, it is possible to put some of the items in a bag in such a way that it should not be greater than the weight of the knapsack • If $V_1, V_2, V_3…..V_4$ are ...

... **EI- Gamal Cryptography** - EI gamal cryptography works in 3 steps/stages $\hspace{1.5cm}$a. Key generation $\hspace{1.5cm}$b. EI gamal encryption $\hspace{1.5cm}$c. EI gamal decryption **A. EI gamal key generation:** 1. Select a large prime number ‘P’ 2. Select encryption key $‘E_1’$ 3. S ...