Lasso FAQ
=========
Generalities
------------
1. What is Lasso ?
Lasso is a C library which implements the identity federation and single-sign
on protocol standards ID-FF 1.2 and SAML 2.0. It also implements attribute
exchange
2. What does Lasso mean ?
Lasso is the acronym of Liberty Alliance Single Sign On.
2. What is Liberty Alliance ?
It'a consortium built to propose a common XML standard for transmitting
information about authentication and identity, made in response to the
Microsoft Passport technology. It has since been dismantled and all its assets
are now managed by the Oasis standard body and the Kantara initiative.
The more recent standard coming from the initial Liberty Alliance initiative
is SAML 2.0.
Use of the library
------------------
1. How to make a simple POST assertion consumer using Python ?
Using Python&WSGI:
.. code-block:: python
import sys
import lasso
from wsgiref.simple_server import make_server
import logging
import urlparse
logging.basicConfig(level=logging.DEBUG)
sp_metadata_xml = '''
urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress
Example SAML 2.0 metadatas
'''
idp_metadata_xml = '''
4yalpsp9Sxlsj07PEI8jJxhSJdo4F0iW0H8u1dhwmsW5YQvRUw/yPlmC09q4WjImmnFVNCJarAOYeFgQCxfIoBasKNnUeBQpogo8W0Q/3mCuKl6lNSr/PIuxMVVNPDWmWkhHXJx/MVar2IREKa1P4jHL0Uxl69/idLwc7TtK1h8=
AQAB
wLu5SdmwyS4o1On/aw4nElLGERFG931exvkzu0ewaM1/oUyD3dO7UC5xMGnPfc6IaH5BcJc3fLr6PJhX55ZrMR98ToPwoUFwuLKK43exwYBEBOOMe1CrCB/Bq+EH6/2sKNXKfgJqj06/3yzafLRiWpMxy2isllxMAvaZXrkpm4c=
AQAB
'''
def app(environ, start_response):
server = lasso.Server.newFromBuffers(sp_metadata_xml)
server.addProviderFromBuffer(lasso.PROVIDER_ROLE_IDP, idp_metadata_xml)
login = lasso.Login(server)
try:
data = environ['wsgi.input'].read(int(environ['CONTENT_LENGTH']))
qs = urlparse.parse_qs(data)
try:
login.processAuthnResponseMsg(qs['SAMLResponse'][0])
except (lasso.DsError, lasso.ProfileCannotVerifySignatureError):
raise Exception('Invalid signature')
except lasso.Error:
raise Exception('Misc error')
try:
login.acceptSso()
except lasso.Error:
raise Exception('Invalid assertion')
except Exception, e:
start_response('500 Internal Error', [('content-type', 'text/plain')],
sys.exc_info())
return ['Erreur: ', str(e)]
else:
start_response('200 Ok', [('content-type', 'text/plain')], sys.exc_info())
return ['You are identified as ', login.assertion.subject.nameId.content]
s = make_server('0.0.0.0', 8081, app)
s.serve_forever()
2. How to make a simple POST assertion consumer using PHP5 ?
Put the following content in a file named index.php:
.. code-block:: php
require "lasso.php";
$sp_metadata_xml = <<<'XML'
urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress
Example SAML 2.0 metadatas
XML;
$idp_metadata_xml = <<<'XML'
4yalpsp9Sxlsj07PEI8jJxhSJdo4F0iW0H8u1dhwmsW5YQvRUw/yPlmC09q4WjImmnFVNCJarAOYeFgQCxfIoBasKNnUeBQpogo8W0Q/3mCuKl6lNSr/PIuxMVVNPDWmWkhHXJx/MVar2IREKa1P4jHL0Uxl69/idLwc7TtK1h8=
AQAB
wLu5SdmwyS4o1On/aw4nElLGERFG931exvkzu0ewaM1/oUyD3dO7UC5xMGnPfc6IaH5BcJc3fLr6PJhX55ZrMR98ToPwoUFwuLKK43exwYBEBOOMe1CrCB/Bq+EH6/2sKNXKfgJqj06/3yzafLRiWpMxy2isllxMAvaZXrkpm4c=
AQAB
XML;
if (isset($_GET["metadata"])) {
header('Content-Type: text/xml');
echo $sp_metadata_xml;
exit(0);
}
if (isset($_GET["assertion_consumer"])) {
$server = LassoServer::newFromBuffers($sp_metadata_xml);
$server->addProviderFromBuffer(LASSO_PROVIDER_ROLE_IDP, $idp_metadata_xml);
$login = new LassoLogin($server);
function error($msg) {
header("HTTP/1.0 500 Internal Error");
?>
Erreur:
echo htmlentities($msg); ?>
exit(0);
}
try {
try {
$login->processAuthnResponseMsg($_POST["SAMLResponse"]);
} catch (LassoDsError $e) {
error('Invalid signature');
} catch (LassoProfileCannotVerifySignatureError $e) {
error('Invalid signature');
} catch (LassoError $e) {
error('Misc error, ' . $e);
}
try {
$login->acceptSso();
} catch (LassoError $e) {
error('Invalid assertion');
}
} catch (Exception $e) {
error('Unexpected error: ' . $e);
}
?> You are identified as echo $login->assertion->subject->nameId->content;
You must replace the ``$idp_metadata_xml`` variable by your identity provider metadata.
You can indicate to your identity provider the URL
http://yourdomain.com/index.php?metadata as the URL of your metadata file.