require 'httpclient'
require 'base64'
require 'gssapi'
uri = URI.parse "https://example.org/ews/Services.wsdl" # MS Exchange Web Services
service = 'HTTP'
cli = HTTPClient.new
gsscli = GSSAPI::Simple.new(uri.host, service)
# initiate the security context.  The output token needs to be sent to the remote server.
token = gsscli.init_context
# Send the output token as part of the Authorization header
ext_head = {"Authorization" => "Negotiate #{Base64.strict_encode64(token)}"}
resp = cli.get(uri, nil, ext_head)
# Get the response 'WWW-Authenticate' header for Negotiate. It will contain the token needed to
# finalize the security context.
itok = resp.header["WWW-Authenticate"].pop.split(/\s+/).last
gsscli.init_context(Base64.strict_decode64(itok))  # The context should now return true