Integration of TLS 1.2 Mandate

TLS1.2 is advanced version of SSL

TLS is a successor to Secure Sockets Layer protocol or SSL. TLS provides secure communications on the Internet for such things as email, Internet faxing, and other data transfers. Client-server applications use the TLS protocol to communicate across a network in a way designed to prevent eavesdropping and tampering.

Since applications can communicate either with or without TLS (or SSL), it is necessary for the client to indicate to the server the setup of a TLS connection. One of the main ways of achieving this is to use a different port number for TLS connections, for example, port 443 for HTTPS.

Once the client and server have agreed to use TLS, they negotiate a stateful connection by using a handshaking procedure. TLS 1.2 was defined in RFC 5246 in August 2008. It is based on the earlier TLS 1.1 specification.

for TLS1.2 your application should be targeting .Net Framework 4.6.2 or above

for e.g in my application i have changed this

ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3 | SecurityProtocolType.Tls;

to

ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;