TLS/SSL overview (Schannel SSP)

Applies to: Windows Server 2022, Windows Server 2019, Windows Server 2016, Windows 10

This topic for the IT professional introduces the TLS and SSL implementations in Windows using the Schannel Security Service Provider (SSP) by describing practical applications, changes in Microsoft's implementation, and software requirements, plus additional resources for Windows Server 2012 and Windows 8.


Schannel is a Security Support Provider (SSP) that implements the Secure Sockets Layer (SSL) and Transport Layer Security (TLS) Internet standard authentication protocols.

The Security Support Provider Interface (SSPI) is an API used by Windows systems to perform security-related functions including authentication. The SSPI functions as a common interface to several SSPs, including the Schannel SSP.

TLS versions 1.0, 1.1, and 1.2, SSL versions 2.0 and 3.0, as well as the Datagram Transport Layer Security (DTLS) protocol version 1.0, and the Private Communications Transport (PCT) protocol are based on public key cryptography. The Schannel authentication protocol suite provides these protocols. All Schannel protocols use a client/server model.


One problem when you administer a network is securing data that is being sent between applications across an untrusted network. You can use TLS and SSL to authenticate servers and client computers and then use the protocol to encrypt messages between the authenticated parties.

For example, you can use TLS/SSL for:

  • SSL-secured transactions with an e-commerce website
  • Authenticated client access to an SSL-secured website
  • Remote access
  • SQL access
  • E-mail


TLS and SSL protocols use a client/server model and are based on certificate authentication, which requires a public key infrastructure.

Server Manager information

There are no configuration steps necessary to implement TLS, SSL or Schannel.

Additional References