Try adding proxyPort to catalina-server.xml
which can be found at <IS_HOME>/repository/conf/tomcat
folder as follows,
<Connector protocol="org.apache.coyote.http11.Http11NioProtocol"
port="9443"
proxyPort="443"
And you'll need to change redirect url of ssoservice as well which can be found in <IS_HOME>/repository/conf/identity.xml
file. Find for <SSOService>
tag and edit <IdentityProviderURL>
like follows,
<IdentityProviderURL>https://localhost:443/samlsso</IdentityProviderURL>
EDIT : Better to use IdentityProviderURL without the default port.
<IdentityProviderURL>https://localhost/samlsso</IdentityProviderURL>
Since 443 is the default port and there might be validation fails when it redirect to url with port and original request sent without the port.
HTH,
DarRay.