In Peoplesoft how connectivity works.

2 Tier - The Client to the Database connection is through SQL and uses the connection security like ODBC or TSN Names.

The connect ID in PeopleTools 8 and greater (or OPRID in PT 7.x) granted at the database level, has READ-ONLY rights to the following tables in order to authenticate the user:

PS.PSDBOWNER – Oracle and DB2 ONLY
PSLOCK – PT 7.5x ONLY
PSSTATUS – PT 8.x and forward releases ONLY, and all platforms
PSOPRDEFN – All tools versions and all platforms
PSACCESSPRFL – All tools versions and all platforms

Once the user is authenticated, through the check against the PSOPRDEFN table, the connection is disconnected and the user is logged in as the access id, which has full access to all PeopleSoft tables.

3 Tier - The Client to the App Server connection is through Tuxedo then the App Server makes a 2-tier connection to the database through SQL as explained above.

4 Tier - The Browser to the web server uses HTTP\HTML, the Web server to the App Server uses JOLT, and the App Server to the Database uses SQL.

SSL would be applied at any part you would need to secure outside your firewall.