Please add a new field type: password

Would you please add an other field type? We need an encrypted field to store users' password of 3rd party sofeware, in order to implement "Single-Sign-In" feature within drupal.
For now, we can only use "single-line textfield" instead, but:
1. It should be shadowed to "********" when input;
2. It should be encrypted in the database;
3. It shouldn't be displayed in the user's view page;

Would you please help me?
Thanks a lot in advance!