Overview of SQL Server Reporting Services 2012 Architecture, Features, and Tools - Learning SQL Server Reporting Services 2012 - page 160

RSWindowsKerberos Kerberos No For requests that specify

Kerberos authentication,
the Report Server reads
permissions on the security
token of the user who issued
the request. If delegation
is enabled in the domain,
the token of the user who is
requesting a report can also
be used on an additional
connection to the external
data sources that provide
data to reports.
Before you specify
RSWindowsKerberos, be
sure that the browser type
you are using actually
supports it. If you are
using Internet Explorer,
Kerberos authentication is
only supported through
Negotiate. Internet Explorer
will not formulate an
authentication request that
specifies Kerberos directly.

RSWindowsBasic Basic No Basic authentication is

defined in the HTTP
protocol and can only be
used to authenticate HTTP
requests to the Report
Server.
Credentials are passed in
the HTTP request in base
64 encoding. If you use
Basic authentication, use
Secure Sockets Layer (SSL)
to encrypt user account
information before it is
sent across the network.
SSL provides an encrypted
channel for sending a
connection request from the
client to the Report Server
over an HTTP TCP/IP
connection.