Authentication, Authorization, Oauth, SAML
Basic Authentication with HTTP
"HTTP/1.0", includes the specification for a Basic Access Authentication scheme. This scheme is not considered to be a secure method of user authentication (unless used in conjunction with some external secure system such as SSL ), as the user name and password are passed over the network as cleartext.
If an HTTP receives an anonymous request for a protected resource it can force the use of Basic authentication by rejecting the request with a 401 (Access Denied) status code and setting the WWW-Authenticate response header as shown below:
HTTP/1.1 401 Access Denied WWW-Authenticate: Basic realm="My Server" Content-Length: 0
the Digest scheme is based on a simple challenge-response paradigm. The Digest scheme challenges using a nonce value. A valid response contains a checksum (by default, the MD5 checksum) of the username, the password, the given nonce value, the HTTP method, and the requested URI. In this way, the password is never sent in the clear. Just as with the Basic scheme, the username and password must be prearranged in some fashion not addressed by this document.
Single Sign-On (SSO) with Oauth and SAML
SSO (Single Sign On) occurs when a user logs in to one Client and is then signed in to other Clients automatically, regardless of the platform, technology, or domain the user is using.
Single sign-on (SSO) is a session and user authentication service that permits a user to use one set of login credentials (e.g., name and password) to access multiple applications. The service authenticates the end user for all the applications the user has been given rights to and eliminates further prompts when the user switches applications during the same session.
SSO A good example of the use of SSO is in Google’s services. You need only be signed in to one primary Google account to access different services like YouTube, Gmail, Google+, Google Analytics, and more.
OAuth is an open standard for authorization, commonly used as a way for Internet users to authorize websites or applications to access their information on other websites but without giving them the passwords.
SAML (Security Assertion Markup Language)
Security Assertion Markup Language (SAML, pronounced sam-el) is an XML-based, open-standard data format for exchanging authentication and authorization data between parties, in particular, between an identity provider and a service provider.
SAML is an XML-based framework that allows identity and security information to be shared across security domains.
The Assertion, an XML security token, is a fundamental construct of SAML that is often adopted for use in other protocols and specifications.