Privacy
Policy.
Effective Date: May 24, 2026
Introduction & Scope
Rewarder operates a canteen loyalty reward system. We are committed to transparency in how we collect, process, and protect your data. This Privacy Policy details the metrics and safeguards in place when you authenticate using Google, scan printed physical receipts, and redeem tokens at affiliated canteens.
Information We Collect
To provide loyalty points tracking and secure verification, we collect and process the following categories of information:
- Account profile details: We use Google OAuth to securely sign you in. We store your unique user ID, email address, display name, and profile picture.
- Receipt scans & metadata: When you snap a live photo of a receipt, we process the image to extract transaction records, including: the canteen name, date, time, total bill amount, and specific line items (quantities, item names, and prices).
- Security & anti-tamper logs: We synchronize your device's monotonic clock offsets against our servers to create a secure Monotonic Time Anchor. We also record basic browser user-agent details during scans to help prevent double-spending and scripting exploits.
Receipt Processing & AI Extraction
When you submit a receipt image, the raw Base64 data is processed server-side via the Vercel AI SDK. We pass the image to multimodal models (like Gemma 4 and fallback models) under strict instructions. The AI extracts structured details (such as the FSSAI registration number and item details) to compute your loyalty points. Raw receipt image buffers are processed on secure cloud hosts and are not shared with external advertising networks.
Data Security & Anti-Fraud Hash
To ensure integrity and prevent double-spending, our server calculates a unique, high-entropy cryptographic signature (Claim Hash) matching the format SHA-256(Bill_Number + Date + Time + Total_Amount). Once generated, this identifier is written to the database. Subsequent scans yielding the same Claim Hash are flagged immediately as duplicates and rejected to protect the integrity of the canteen loyalty system.
Retention & Third Parties
Your data is stored securely using encrypted cloud databases.
- Active claim records: Extracted metadata and hash signatures are kept indefinitely to enforce double-spend rules and allow canteen auditing.
- Authentication details: Stored and managed securely via our authentication server powered by Better Auth.
- Third-party sharing: We do not sell, license, or distribute your account info or dining logs. Data is shared only with our infrastructure suppliers (such as Cloudflare Workers hosting and Google/Groq AI endpoints) to fulfill the receipt scanning functions.
Changes & Contact
We reserve the right to modify this Privacy Policy as canteen networks grow or reward rates adjust. Any changes will be updated on this page with a revised date. If you have questions about your loyalty profile, data storage, or want to request account deletion, please contact your Canteen Management Committee.