Privacy

Coffee Ledger is a trust-based departmental ledger. It does not prove anyone's real-world identity.

What is stored

Your username, display name and Chair; for members the university e-mail address, for guests the account of the sponsor who vouched for them; your password only as a salted hash; every coffee and every payment with date, amount and price; a record of each browser session (a hashed random token, creation, last use and expiry); and an audit log of administrative actions, including changes of a Chair.

No analytics, trackers or third-party services are used. E-mail addresses are used only to send you the mails described here.

Why

To keep a fair account of who owes how much for the shared coffee machine, and to be able to correct mistakes.

Who can see it

Every verified, signed-in account can see on the department website: your display name, your Chair, your balance (in words: what you owe or your credit), the number of coffees (this month and in total), your complete history of coffees and payments (date, shots, price, amount), the names of the group admins of each Chair and the group balances (money collected, handed over and still held). Visitors who are not signed in cannot see any of it.

What is never shown

No e-mail address, no username and no password data is ever shown to other users. The same holds for sessions, IP addresses, notes and the audit log, and for which administrator recorded an entry. Your username and e-mail address are used only for signing in and for the mails described here.

Administrators of the department can additionally see accounts and ledgers in the admin area (group admins only those of their own Chair).

Retention

Ledger entries are kept as long as the coffee ledger is operated, because balances are derived from the complete history. Expired browser sessions are purged regularly.

You can deactivate your account under My account, or an administrator can do it. Deactivation anonymizes the display name (Alumni N) and clears the login name and e-mail from the account; the ledger UUID, Chair and history stay. For 90 days you can restore the original identity by signing in with the same username and password (or an administrator can restore it). After that the original name and e-mail cannot be restored. Ledger entries and the audit log are never deleted.

Contact

Johannes Hauschild <johannes.hauschild@tum.de>